TERMINALS

TECHNICAL FIELD

The present disclosure relates generally to communications, and more particularly to wireless communications and related methods and wireless terminals.

BACKGROUND

Device-to-device (D2D) communication in the cellular spectrum (which may

interchangeably be referred to herein as proximity services (ProSe) or sidelink communication) has been studied during the last decade both in the research community and in industry. Many existing wireless technologies, especially in the field of ad hoc networks, are based on the concept of D2D. Examples include Bluetooth and several variants of the IEEE 802.11 standards suite, such as WiFi Direct, and IEEE 802.15.3, such as ZigBee, WirelessHART, etc. These systems operate in unlicensed spectrum.

On the other hand, the concept of applying D2D in the licensed cellular spectrum is relatively new and particularly challenging due to need to develop a new framework in which D2D and legacy cellular communication can coexist and possibly share the same cellular spectrum.

The basic idea of D2D is the possibility of allowing two UEs (also referred to as wireless terminals) in proximity of each other to communicate without the need to relay the traffic through the network. Therefore D2D communications have the potential to exploit the proximity gain of the two UEs which may imply reduced/low latency and possibly higher data rates.

Moreover, because of the potential non-orthogonal resource sharing between the cellular and the D2D layers it may be possible to have a reuse gain that increases the resource utilization. In general, D2D technology seems to be tailored for some applications that are based on proximity (e.g., social networking, gaming, local advertisements, group communications, etc.). D2D may also be useful in the field of safety services (e.g., NSPS services, road safety systems, etc.)

Because of such reasons, the 3GPP standardization body has recently included in 3GPP Release-12 support for D2D, which in 3GPP terminology is also referred to as ProSe or sidelink. In particular, 3GPP Release-12 has considered two possible ProSe techniques: ProSe Communications and ProSe Discovery. ProSe communications imply that UEs in the proximity of each other establish a direct user plane connection. In ProSe Discovery, UEs transmit and monitor discovery announcements to become aware of the type of content/service each UE can share in D2D fashion, as well as the proximity between each other. More specifically, when performing direct communications, 3GPP defines two different operative modes: mode 1, in which a UE in RRC CONNECTED mode requests D2D resources and the eNB grants them; and mode 2, where a UE (potentially in RRC IDLE) autonomously selects resources for

transmission. Similarly, for direct discovery, 3 GPP considers type 1 in which the UE

autonomously selects radio resources for discovery, and type 2 where a UE in

RRC CONNECTED mode requests resources for discovery and the eNB grants them via RRC (Radio Resource Control).

Therefore, while in certain scenarios a control node (e.g., eNB) explicitly assigns resources (e.g. via a PDCCH grant) to each device for D2D operation, in other scenarios the devices autonomously select the transmitting resources from a pool of resources that is provided by the network. This type of autonomous/distributed resource allocation scheme may be used in this case, with reduced signaling and dependency on the control node as compared to centralized resource allocation. However, as previously mentioned, also in distributed schemes the UEs may be typically constrained to use resources belonging to a possibly periodic resource pool, typically consisting of a set of time and frequency resources. Such pool of resources is broadcasted by the eNB in the SIB 18 for ProSe communication and in the SIB 19 is used for ProSe discovery.

Multi-carrier D2D operations are also considered in the 3 GPP standardization body both for ProSe Communication (since 3GPP Release-12) and ProSe Discovery (since 3GPP Release- 13). In particular, D2D communication within LTE (Long Term Evolution) should be able to work also inter-PLMN (as well as intra-PLMN but inter -carrier). This means that a device operating under a first operator subscription on a first carrier frequency should be able to discover (and also communicate) with a second device operating under a second operator subscription on a second carrier frequency. Multi-carrier operations, for example, may allow for a UE to have cellular communication on a certain carrier (e.g., the primary carrier) and at the same time perform ProSe operations on any other carrier which can also be a

dedicated/preconfigured ProSe carrier used, for example, for public safety purposes or a carrier that is currently out-of-network-coverage. In any case, the carrier in which ProSe operates might not be under the control of the serving eNB in which the UE is currently connected or is camping, meaning that the network might not be able to provide system information for that carrier or assign transmission resources.

Multi-carrier D2D communications may provide multiple benefits. For example, since D2D communication exploits the ordinary cellular spectrum, it may be of importance to better exploit the available carriers to reduce/limit impact on quality of service of the cellular layer. Therefore, this feature may allow load balancing mechanisms to have a better load distribution among carriers and eventually an increased QoS (Quality of Service) for both cellular and D2D communications. Additionally, having multiple carriers available for D2D communications may widen a range of services/applications that the D2D technology can satisfy (e.g., as mentioned earlier it may give the possibility to deploy dedicated carriers for specific services like NSPS).

In the event that a wireless terminal uses a carrier for D2D communications that is not under control of the service eNB with which the wireless terminal is currently connected or camping, the network may be unable to provide system information and/or assign resources for the carrier being used for D2D communications.

The approaches described above could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described above are not prior art to embodiments in this application and are not admitted to be prior art by inclusion above.

SUMMARY

According to some embodiments of inventive concepts, a method of operating a wireless terminal using a first carrier and a second carrier different than the first carrier may be provided. System information may be received over the second carrier including a resource configuration identifying subframes of the second carrier available for device-to-device, D2D, operations. A D2D gap request may be transmitted to a serving base station of a radio access network, RAN, wherein the D2D gap request includes an identification of the second carrier and the resource configuration identifying subframes of the second carrier available for D2D operations. After receiving the system information and after transmitting the D2D gap request, D2D configuration information may be received from the serving base station of the RAN using the first carrier as a serving carrier, with the D2D configuration information being for the second carrier. D2D operations may be performed using the second carrier based on the D2D configuration information for the second carrier.

Before receiving the D2D configuration information from the base station, subframes in which D2D operations should be performed may be compared with a discontinuous reception, DRX, pattern. Transmitting the D2D gap request may include transmitting the D2D gap request responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of the DRX pattern.

Receiving the system information may include receiving the system information before receiving the D2D configuration information from the base station, while engaged in cellular communications using the first carrier of the serving base station, and responsive to determining that no receiver/transmitter chain is available for D2D operations using the second carrier. In addition, transmitting the D2D gap request may include transmitting the D2D gap request responsive to determining a difference between the resource configuration of the system information from the second carrier and a previous resource configuration from the second carrier. Moreover, transmitting the D2D gap request may include transmitting the D2D gap request responsive to determining the difference between the resource configuration of the system information from the second carrier and the previous resource configuration from the second carrier, and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of a discontinuous reception, DRX, pattern.

Receiving the system information may include receiving the system information before receiving the D2D configuration information from the base station, while engaged in cellular communications using the first carrier of the serving base station, and responsive to determining that no receiver/transmitter chain is available for D2D operations using the second carrier. Moreover, transmitting the D2D gap request may include transmitting the D2D gap request responsive to the resource configuration of the system information from the second carrier being a first resource configuration received for the second carrier since entering a current connected mode with the serving base station. In addition, transmitting the D2D gap request may include transmitting the D2D gap request responsive to the resource configuration of the system information from the second carrier being a first resource configuration received for the second carrier since entering the current connected mode with the serving base station and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of a discontinuous reception, DRX, pattern.

The second carrier may be used by a second base station different than the first base station, and/or performing D2D operations may include performing D2D discovery operations.

According to some other embodiments of inventive concepts, a method of operating a wireless terminal using a first carrier and a second carrier different than the first carrier may be provided. Subframes in which device-to-device, D2D, operations should be performed may be compared with a discontinuous reception, DRX, pattern. Responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of the DRX pattern, a D2D gap request may be transmitted to a serving base station of a radio access network, RAN, with the D2D gap request including an identification of the second carrier and a resource configuration identifying subframes of the second carrier available for D2D operations. After comparing subframes and after transmitting the D2D gap request, D2D configuration information may be received from the serving base station of the RAN using the first carrier as a serving carrier, with the D2D configuration information being for the second carrier. D2D operations may be performed using the second carrier based on the D2D configuration information for the second carrier.

The second carrier may be used by a second base station different than the first base station, and/or performing D2D operations may include performing D2D discovery operations.

According to still other embodiments of inventive concepts, a wireless terminal may be adapted to receive system information over a second carrier including a resource configuration identifying subframes of the second carrier available for device-to-device, D2D, operations. The wireless terminal may also be adapted to transmit a D2D gap request to a serving base station of a radio access network, RAN, with the D2D gap request including an identification of the second carrier and the resource configuration identifying subframes of the second carrier available for D2D operations. The wireless terminal may be further adapted to receive D2D configuration information from the serving base station of the RAN using a first carrier as a serving carrier after receiving the system information and after transmitting the D2D gap request, with the D2D configuration information being for the second carrier and the second carrier being different than the first carrier. In addition, the wireless terminal may be adapted to perform D2D operations using the second carrier based on the D2D configuration information for the second carrier. The wireless terminal may be further adapted to compare subframes in which D2D operations should be performed with a discontinuous reception, DRX, pattern before receiving the D2D configuration information from the base station. In addition, transmitting the D2D gap request may include transmitting the D2D gap request responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of the DRX pattern.

Receiving the system information may include receiving the system information before receiving the D2D configuration information from the base station, while engaged in cellular communications using the first carrier of the serving base station, and responsive to determining that no receiver/transmitter chain is available for D2D operations using the second carrier. In addition, transmitting the D2D gap request may include transmitting the D2D gap request responsive to determining a difference between the resource configuration of the system information from the second carrier and a previous resource configuration from the second carrier. In addition, transmitting the D2D gap request may include transmitting the D2D gap request responsive to determining the difference between the resource configuration of the system information from the second carrier and the previous resource configuration from the second carrier, and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of a discontinuous reception, DRX, pattern.

Receiving the system information may include receiving the system information before receiving the D2D configuration information from the base station, while engaged in cellular communications using the first carrier of the serving base station, and responsive to determining that no receiver/transmitter chain is available for D2D operations using the second carrier. In addition, transmitting the D2D gap request may include transmitting the D2D gap request responsive to the resource configuration of the system information from the second carrier being a first resource configuration received for the second carrier since entering a current connected mode with the serving base station. Moreover, transmitting the D2D gap request may include transmitting the D2D gap request responsive to the resource configuration of the system information from the second carrier being a first resource configuration received for the second carrier since entering the current connected mode with the serving base station and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of a discontinuous reception DRX pattern. According to yet other embodiments of inventive concepts, a wireless terminal may include a transceiver configured to provide wireless communication with one or more nodes of a radio access network, RAN, and a processor coupled with the transceiver. The processor may be configured to transmit and/or receive communications to/from the one or more nodes of the RAN through the transceiver. The processor may be configured to receive system information over a second carrier including a resource configuration identifying subframes of the second carrier available for device-to-device, D2D, operations. The processor may also be configured to transmit a D2D gap request to a serving base station of the RAN, wherein the D2D gap request includes an identification of the second carrier and the resource configuration identifying subframes of the second carrier available for D2D operations. The processor may be further configured to receive D2D configuration information from the serving base station of the RAN using a first carrier as a serving carrier after receiving the system information and after transmitting the D2D gap request, with the D2D configuration information being for the second carrier and the second carrier being different than the first carrier. In addition, the processor may be configured to perform D2D operations using the second carrier based on the D2D

configuration information for the second carrier.

The processor may be further configured to compare subframes in which D2D operations should be performed with a discontinuous reception, DRX, pattern before receiving the D2D configuration information from the base station. Transmitting the D2D gap request may include transmitting the D2D gap request responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of the DRX pattern.

Receiving the system information may include receiving the system information before receiving the D2D configuration information from the base station, while engaged in cellular communications using the first carrier of the serving base station, and responsive to determining that no receiver/transmitter chain is available for D2D operations using the second carrier. In addition, transmitting the D2D gap request may include transmitting the D2D gap request responsive to determining a difference between the resource configuration of the system information from the second carrier and a previous resource configuration from the second carrier. Moreover, transmitting the D2D gap request may include transmitting the D2D gap request responsive to determining the difference between the resource configuration of the system information from the second carrier and the previous resource configuration from the second carrier, and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of a discontinuous reception, DRX, pattern.

Receiving the system information may include receiving the system information before receiving the D2D configuration information from the base station, while engaged in cellular communications using the first carrier of the serving base station, and responsive to determining that no receiver/transmitter chain is available for D2D operations using the second carrier. In addition, transmitting the D2D gap request may include transmitting the D2D gap request responsive to the resource configuration of the system information from the second carrier being a first resource configuration received for the second carrier since entering a current connected mode with the serving base station. Moreover, transmitting the D2D gap request may include transmitting the D2D gap request responsive to the resource configuration of the system information from the second carrier being a first resource configuration received for the second carrier since entering the current connected mode with the serving base station and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of a discontinuous reception, DRX, pattern.

According to further embodiments of inventive concepts, a wireless terminal may include a system information reception module configured to receive system information over a second carrier including a resource configuration identifying subframes of the second carrier available for device-to-device, D2D, operations. The wireless terminal may also include a D2D gap request transmission module configured to transmit a D2D gap request to a serving base station of a radio access network, RAN, with the D2D gap request including an identification of the second carrier and the resource configuration identifying subframes of the second carrier available for D2D operations. The wireless terminal may further include a D2D configuration information reception module configured to receive D2D configuration information from the serving base station of the RAN using a first carrier as a serving carrier after receiving the system information and after transmitting the D2D gap request, with the D2D configuration information being for the second carrier and the second carrier being different than the first carrier. In addition, the wireless terminal may include a D2D operations performance module configured to perform D2D operations using the second carrier based on the D2D configuration information for the second carrier. According to some further embodiments of inventive concepts, a wireless terminal may be adapted to compare subframes in which device-to-device, D2D, operations should be performed with a discontinuous reception, DRX, pattern. The wireless terminal may also be adapted to transmit a D2D gap request to a serving base station of a radio access network, RAN, responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of the DRX pattern, with the D2D gap request including an identification of a second carrier and a resource configuration identifying subframes of the second carrier available for D2D operations. The wireless terminal may further be configured to receive D2D configuration information from the serving base station of the RAN using a first carrier as a serving carrier after comparing subframes and after transmitting the D2D gap request, with the D2D configuration information being for the second carrier and the second carrier being different than the first carrier. In addition, the wireless terminal may perform D2D operations using the second carrier based on the D2D configuration information for the second carrier.

According to still further embodiments of inventive concepts, a wireless terminal may include a transceiver configured to provide wireless communication with one or more nodes of a radio access network, RAN, and a processor coupled with the transceiver. The processor may be configured to transmit and/or receive communications to/from the one or more nodes of the RAN through the transceiver. The processor may be configured to compare subframes in which device-to-device D2D operations should be performed with a discontinuous reception, DRX, pattern. The processor may be configured to transmit a D2D gap request to a serving base station of the RAN responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of the DRX pattern, with the D2D gap request including an identification of a second carrier and a resource configuration identifying subframes of the second carrier available for D2D operations. The processor may be configured to receive D2D configuration information from the serving base station of the RAN using a first carrier as a serving carrier after comparing subframes and after transmitting the D2D gap request, with the D2D configuration information being for the second carrier with the second carrier being different than the first carrier. The processor may be configured to perform D2D operations using the second carrier based on the D2D configuration information for the second carrier. According to yet further embodiments of inventive concepts, a wireless terminal may include a subframe comparison module configured to compare subframes in which device-to- device, D2D, operations should be performed with a discontinuous reception, DRX, pattern. The wireless terminal may include a D2D gap request transmission module configured to transmit a D2D gap request to a serving base station of a radio access network, RAN, responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of the DRX pattern, with the D2D gap request including an identification of a second carrier and a resource configuration identifying subframes of the second carrier available for D2D operations. The wireless terminal may include a D2D configuration information reception module configured to receive D2D configuration information from the serving base station of the RAN using a first carrier as a serving carrier after comparing subframes and after transmitting the D2D gap request, with the D2D configuration information being for the second carrier with the second carrier being different than the first carrier. The wireless terminal may include a D2D operations performance module configured to perform D2D operations using the second carrier based on the D2D configuration information for the second carrier.

According to some embodiments disclosed herein, improved setup of D2D gap configurations may be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in a constitute a part of this application, illustrate certain non-limiting embodiments of inventive concepts. In the drawings:

Figure 1 is a signaling diagram illustrating signaling related to wireless terminal UE initiated gap requests according to some embodiments of inventive concepts;

Figure 2 is a signaling diagram illustrating a base station eNB initiated gap request procedure according to some embodiments of inventive concepts;

Figure 3 is a signaling diagram illustrating a base station eNB initiated gap request procedure according to some embodiments of inventive concepts;

Figure 4 is a flow chart illustrating operations according to some embodiments of inventive concepts; Figure 5 is a block diagram illustrating base stations of a radio access network in communication with wireless terminals according to some embodiments of inventive concepts;

Figure 6 is a block diagram illustrating elements of a base station of Figure 5 according to some embodiments of inventive concepts;

Figure 7 is a block diagram illustrating elements of a wireless terminal of Figure 5 according to some embodiments of inventive concepts;

Figure 8 is a flow chart illustrating operations of a wireless terminal of Figure 7 and Figure 9 is a block diagram illustrating related modules according to some embodiments of inventive concepts; and

Figure 10 is a flow chart illustrating operations of a wireless terminal of Figure 7 and Figure 11 is a block diagram illustrating related modules according to some other embodiments of inventive concepts.

DETAILED DESCRIPTION

Inventive concepts will now be described more fully hereinafter with reference to the accompanying drawings, in which examples of embodiments of inventive concepts are shown. Inventive concepts may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of inventive concepts to those skilled in the art. It should also be noted that these embodiments are not mutually exclusive. Components from one embodiment may be tacitly assumed to be present/used in another embodiment.

For purposes of illustration and explanation only, these and other embodiments of inventive concepts are described herein in the context of operating in a RAN (Radio Access Network) that communicates over radio communication channels with wireless terminals (also referred to as UEs). It will be understood, however, that inventive concepts are not limited to such embodiments and may be embodied generally in any type of communication network. As used herein, a legacy or non-legacy wireless terminal (also referred to as a UE, user equipment node, mobile terminal, etc.) can include any device that receives data from and/or transmits data to a communication network, and may include, but is not limited to, a mobile telephone ("cellular" telephone), laptop/portable computer, pocket computer, hand-held computer, and/or desktop computer.

Note that although terminology from 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) has been used in this disclosure to provide examples of embodiments of inventive concepts, this should not be seen as limiting the scope of inventive concepts to only the aforementioned system. Other wireless systems, including WCDMA, WiMax, UMB and GSM, may also benefit from exploiting ideas/concepts covered within this disclosure.

Also, note that terminology such as base station (also referred to as a eNodeB, eNB, etc.) and wireless terminal (also referred to as a mobile station, mobile terminal, UE, etc.) should be considered non-limiting and does not imply a certain hierarchical relation between the two. In general, a base station or "eNodeB" could be considered as a first device and a wireless terminal or "UE" could be considered as a second device, and these two devices may communicate with each other over some radio channel.

Figure 5 is a block diagram illustrating a Radio Access Network (RAN) according to some embodiments of present inventive concepts. As shown, communications between a plurality of base stations BS-a, BS-b, and BS-c may be provided using respective X2 Interfaces, and communications between base stations and one or more core network nodes MME/S-GW may be provided using respective SI interfaces. Each base station BS may communicate over a wireless radio interface (including uplinks and downlinks) with respective wireless terminals UEs in a respective cell or cells supported by a base station. By way of example, base station BS-a is shown in communication with wireless terminals UE-a, UE-b, and UE-g, base station BS-b is shown in communication with wireless terminals UE-c and UE-d, and base station BS-c is shown in communication with wireless terminals UE-e and UE-f.

Figure 6 is a block diagram illustrating elements of a base station BS (also referred to as an eNB, eNodeB, an evolved NodeB, a radio base station, a RAN node, etc.) of Figure 5. As shown, a base station BS may include a transceiver circuit 201 (also referred to as a transceiver) configured to provide radio communications with a plurality of wireless terminals, a network interface circuit 205 (also referred to as a network interface) configured to provide

communications with other base stations of the RAN (e.g., over the X2 interface), and a processor circuit 203 (also referred to as a processor) coupled to the transceiver circuit and the network interface circuit, and a memory circuit 207 coupled to the processor circuit. The memory circuit 207 may include computer readable program code that when executed by the processor circuit 203 causes the processor circuit to perform operations according to

embodiments disclosed herein. According to other embodiments, processor circuit 203 may be defined to include memory so that a memory circuit is not separately provided. When elements of different base stations are discussed herein, elements thereof may be distinguished by appending respective letters (e.g., "-a", "-b", etc.) to the element numbers (e.g., "201", "203", "205", and "207"). For example, base station BS-a of Figure 5 may include transceiver 201 -a, processor 203 -a, network interface 205-a and memory 207-a, and base station BS-b of Figure 5 may include transceiver 201 -b, processor 203 -b, network interface 205-b, and memory 207-b.

Figure 7 is a block diagram illustrating elements of a wireless terminal UE (also referred to as a mobile terminal, mobile station, a UE, a user equipment, a user equipment node, etc.) of Figure 5. As shown, a wireless terminal UE may include a transceiver circuit 301 (also referred to as a transceiver) configured to provide radio communications with a base station BS, a processor circuit 303 (also referred to as a processor) coupled to the transceiver circuit, and a memory circuit 307 coupled to the processor circuit. The memory circuit 307 may include computer readable program code that when executed by the processor circuit 403 causes the processor circuit to perform operations according to embodiments disclosed herein. According to other embodiments, processor circuit 303 may be defined to include memory so that a memory circuit is not separately provided. When elements of different wireless terminals are discussed herein, elements thereof may be distinguished by appending respective letters (e.g., "-a", "-b", etc.) to the element numbers (e.g., "301", "303", and "305"). For example, wireless terminal UE-a of Figure 5 may include transceiver 301 -a, processor 303-a, and memory 307-a, and wireless terminal UE-b of Figure 5 may include transceiver 301-b, processor 303-b, and memory 307-b.

According to some embodiments discussed below, base station BS-a may be a serving base station for wireless terminals UE-a, UE-b, and UE-g using a first carrier (also referred to as a first frequency carrier), base station BS-b may be a serving base station for wireless terminals UE-c and UE-d using a second carrier (also referred to as a second frequency carrier) different than the first carrier, and base station BS-c may be a serving base station for wireless terminals UE-e and UE-f using a third carrier (also referred to as a third frequency carrier) different than the first and second carriers. Wireless terminal UE-g may thus be in cellular communication and/or in an RRC connected state with base station BS-a as a serving base station. As discussed in greater detail below, wireless terminal UE-g may initiate/conduct D2D operations using the second carrier of base station BS-b while in cellular communication and/or in RRC connected state with base station BS-a to support direct communication with another wireless terminal (e.g., wireless terminal UE-c). While base stations BS-a and BS-b are shown in Figure 5 as elements of a same radio access network, base stations BS-a and BS-b may be base stations of different radio access networks (i.e., different PLMNs).

Despite the mentioned benefits, support of multi-carrier D2D operations (both for ProSe discovery and ProSe communications) may present some challenges. Realizing multi-carrier operations might not be trivial because the UE might not have multiple transmitter/receiver chains. Therefore, to support simultaneous cellular communication and ProSe

discovery/communications, the UE may need to have at least more than one transmitter/receiver chain, which may imply increasing UE capabilities. This might ultimately affect implementation complexity and/or device cost. Therefore, in 3 GPP Release- 12, support of improved UE capabilities related to ProSe discovery have not been mandated and ProSe discovery is down- prioritized with respect to legacy cellular communication, meaning that ProSe discovery can only be performed if the UE is in RRC IDLE or during DRX (Discontinuous Reception) sleeping period.

To improve ProSe performances without necessarily changing UE capabilities in terms of supported RX/TX chains, 3 GPP has agreed in Release 13 to introduce configurable D2D gaps which may allow a UE to perform ProSe discovery thereby skipping cellular communications.

Configuration of D2D gaps and conditions that trigger a gap configuration have not yet been studied by 3 GPP.

A possible solution is that the UE (also referred to as a wireless terminal) applies a D2D gap configuration and informs the eNB (also referred to as a base station) on the D2D gap configuration decision. This solution, however, may not take into account that the eNB might refuse the D2D gap configuration for different reasons (e.g., the gap is requested in subframes that are used by the eNB for legacy cellular operations, such as paging, MBSFN subframes, SIB1, etc., or the UE is currently engaged in high priority cellular communications, or simply the eNB needs to check whether the UE can be trusted or not). Additionally, in some other cases it may be useful if the eNB rather than the UE triggers the D2D gap configuration.

According to some embodiments of inventive concepts, signaling procedures may be defined to configure the D2D gap configuration and under which conditions the D2D gap configuration is triggered. For example, different embodiments are described taking into account that the triggering can be either initiated by the UE, in which case the eNB may or may not acknowledge the gap, or by the network, in which case the network may need to know whether the UE supports or does not support the D2D gaps.

According to some embodiments of inventive concepts, a proper setup of the D2D gap configuration may be allowed. Moreover, embodiments of inventive concepts may define conditions under which the UE is allow to request a D2D gap configuration and conditions under which the network can request the UE to configure a D2D gap, or on the other hand, to accept or not accept the D2D gap configuration requested by the UE.

In the following, embodiments of inventive concepts are presented in the context of ProSe discovery. The disclosed mechanisms, however, may also be applied to other types of transmission (e.g., cellular transmission, ProSe communications, V2X, or when the UE aggregates licensed carriers with unlicensed spectrum like WiFi).

According to some embodiments of inventive concepts, the focus is on signaling a UE uses to communicate to the eNB the D2D gap configuration request (also referred to as a gap request, a D2D gap request, a D2D configuration request, a gap configuration request). Figure 1 illustrates signaling related to UE-initiated gap requests. In Figure 1 , the serving carrier (e.g., used to provide service from a serving base station eNB) and the discovery carrier (e.g., used to provide service from another base station eNB) might belong to different PLMNs or simply to different eNBs (also referred to as base stations) or the discovery carrier can be a dedicated ProSe carrier or an out-of-coverage carrier using preconfigured resources.

The UE may first need to monitor the SIB 19 (System Information Block 19) from the serving carrier from which it becomes aware of the carriers that are providing ProSe Discovery services at message 101. The SIB 19 may identify a resource pattern of the serving carrier (e.g., defining subframes and subbands allowed for ProSe Discovery) using the serving carrier, for example, providing a basis of D2D gap configuration (also referred to as gap configuration, D2D configuration, and/or D2D gap). As a response, the UE sends a SidelinkUEInformation message containing the carrier frequency in which the UE is actually interested to perform discovery (e.g., the carrier frequency of the discovery carrier) at message 102. At this point, the UE starts monitoring the discovery carrier to learn the resource pool that it needs to use to perform ProSe discovery transmission/reception, e.g., using SIB19 (System Information Block 19 transmitted over the discovery carrier) at message 103. The UE might then decide on the basis of certain conditions (that are described in the following embodiments) to trigger a D2D gap configuration request to the serving carrier (i.e., to the eNB) using a GapRequest message including the carrier frequency of the discovery carrier and a resource pattern of the discovery carrier (e.g., defining subframes allowed for ProSe Discovery) at message 104. Such gap request can also be sent in the SidelinkUelnformation message envelope or in any other RRC message, and may contain the carrier in which ProSe discovery is to be performed and also the subframe pattern in which ProSe discovery will be performed. The eNB may decide to accept or not accept the gap request and possibly provide a different subframe pattern configuration to perform discovery using the Gap configuration message at message 105.

The D2D gap configuration request message (also referred to as a D2D gap configuration request, a gap request, a D2D gap request, a D2D configuration request, and/or a gap

configuration request) can also be triggered whenever a new ProSe discovery carrier is selected for ProSe discovery operations or if the discovery resource configuration of the ProSe discovery carrier changes, or if since a last gap request message for a given resource configuration the UE selects different resources for ProSe transmission and/or reception.

Mechanisms disclosed in embodiments of Figure 1 may also apply to the case in which the SIB 19 of the serving carrier also provides the resources for transmission/reception in the ProSe discovery carrier of the other eNB.

According to some other embodiments of inventive concepts, the serving carrier (i.e., the serving eNB) may initiate the gap configuration setup thereby limiting signaling overhead.

However, in order to do that, the eNB may need to know whether the UE supports the D2D gaps or not. This information can be known if gap support is explicitly signaled in the capability message which in LTE is transmitted to the eNB as part of UE capability transfer procedure (see section 5.6.3 in TS 36.331 vl2.6.0).

Figure 2 illustrates an eNB-initiated gap request procedure according to some

embodiments of inventive concepts. As shown, the UE may transmit the UE capability message to the serving eNB using the serving carrier at message 221. The UE capability message may define features/properties of the UE, such as, transmission modes, D2D ProSe

Discovery /Communication capabilities, carrier aggregation capabilities (that may be used to determine Receiver/Transceiver chain capabilities, etc.), etc. The UE may receive system information using SIB 19 from the serving eNB identifying a resource pattern of the serving carrier (e.g., defining subframes allowed for ProSe Discovery) using the serving carrier, for example, providing a basis of gap configuration at message 222.

In this case, upon receiving SidelinkUelnformation (identifying the carrier of the other eNB, referred to as the discovery carrier) at message 223, the serving eNB knows whether the UE supports D2D gap or not. Therefore, the gaps can be configured directly by the serving eNB with the subframe pattern in which ProSe discovery is actually allowed using the Gap configuration message at message 224. The serving eNB, for example, may have information regarding a gap configuration of the other eNB using the discovery carrier, for example, based on communications between the eNBs, based on prior configuration, and/or based on gap configuration requests received from other UEs.

An additional enhancement may consider a case in which the UE upon reading SIBl 9 on the Discovery carrier (transmitted by the eNB using the discovery carrier) at message 225 realizes that the gap configuration provided by the serving carrier does not offer sufficient performance (e.g., too few subframes can be actually used for ProSe discovery

transmission/reception, not enough UEs discovered since last gap configuration, etc.). Thus, the UE can ask the serving eNB using the serving carrier to change the gap configuration and suggest a different pattern (e.g., the "GapChangeReq" message in Figure 2) at message 226. The UE in the "GapChangeReq" may also indicate the reason why a change in the gap configuration is desired (e.g., not enough UEs discovered since last gap configuration or during last discovery periods).

Another option is that the gap configuration from the serving eNB provides a list of banned subframes in which the serving eNB does not want ProSe discovery to be performed. In this case, the UE upon reading SIB 19 in the ProSe discovery carrier selects only the subframes that have been allowed in the gap configuration message and reports such selection to the eNB. The gap configuration message can also be a simple gap request message that triggers the UE to send the desired gap configuration. The mechanism disclosed in this embodiment may also apply to a case in which the SIB 19 of the serving eNB using the serving carrier also provides identification of resources for ProSe discovery transmission/reception over the discovery carrier of the other eNB.

A variant of this embodiment is illustrated in Figure 3 using a base station eNB initiated gap request and dedicated signaling. Messages 221, 222, and 223 of Figure 3 may be the same as discussed above with respect to Figure 2. In this case, the resources for ProSe discovery transmission/reception using the discovery carrier of the other eNB may be provided via dedicated signaling of message 334 rather than from SIB 19 of the discovery carrier. Therefore, regardless of autonomous resource allocation (e.g., type 1 ProSe discovery or mode 2 ProSe communication) or UE-specific resource allocation (e.g., type 2B ProSe discovery or mode 1 ProSe communication), the gap configuration can be configured in the discovery configuration signaling that contains the resources in which ProSe discovery is allowed. The gap configuration can also be only implicitly signaled (i.e. the UE can simply apply the gap in the resources signaled if there is no RX/TX chain available to be dedicated to the ProSe carrier). This latter method may imply that the serving eNB when sending discovery resources (i.e.,

resourcePatternDiscCarrier) allows the UE to perform the D2D gap operations using those resources.

According to still other embodiments of inventive concepts related to the UE-triggered gap request scenario, conditions under which the UE is allowed to trigger a gap request are provided.

Figure 4 is a flow chart illustrating operations according to some embodiments including triggering mechanisms for wireless terminal UE initiated gap request.

In the first decision block 401 of Figure 4, the UE may already be engaged in cellular communications using a serving carrier (of a serving eNB) and it may not have a RX/TX chain available to be dedicated for ProSe discovery operations using a ProSe discovery carrier different than the serving carrier (of another eNB). If this is the case at block 401 , the UE may need to acquire the resource pattern from the SIB 19 related to the ProSe discovery carrier. If this is the first SIB 19 acquisition after entering connected mode or if there is any change with any previous resource pool configuration for the same ProSe discovery carrier at the second decision block 402 of Figure 4, then the gap request may be triggered (i.e., sent to the serving eNB) at block 405. If a negative outcome results from either of the decision blocks 402 or 403 of Figure 4, no gap request is sent at block 404.

A possible improvement to the above discussed procedure of Figure 4 is that the UE before sending the gap request may compare the subframes in which ProSe discovery operations should be performed with a current DRX (Discontinuous Reception) pattern. If the resources selected for ProSe discovery correspond to a DRX sleeping period at block 403, the gap request is not performed at block 404. If discovery subframes happen to collide with subframes in which the UE is currently in DRX active mode (DRX On) due to a DRX inactivity timer,

communication may be prioritized over ProSe discovery operations.

Another possible improvement to the above procedure of Figure 4 is that the UE before sending the gap request checks whether a previous gap request has been sent within a certain time period (e.g. 1 second, 5 seconds etc). If a previous gap request was sent, then the transmission of this gap request is not performed, and is either cancelled or delayed until enough time has transpired for the gap request to be sent. This delay can be implemented with a timer which is started when a gap request is transmitted. While this timer is running, no further gap request may be sent. This timer may be either network configured or preconfigured.

According to still other embodiments of inventive concepts, eNB procedures to trigger gap configuration are discussed. Mechanisms described can be applied both to the case that the gap is triggered by the UE or to the case that the gap is triggered by the eNB. The eNB before configuring the gap may check in the UE capability, if the UE has an available RX/TX

(receiver/transmitter) chain that can be dedicated to the ProSe discovery carrier indicated by the UE in SidelinkUelnformation message. This can be deduced from the UE capabilities relating to carrier aggregation (e.g., the supported band combinations).

If the eNB deduces that the UE has no available RX/TX chain to be dedicated to the ProSe discovery carrier indicated by the UE in the SidelinkUEInformation message, the eNB may take one of the following actions to free an RX/TX chain in the UE, or to reuse the same RX/TX chain used for cellular communication:

1. Hand over the UE to the eNB using the ProSe discovery carrier indicated by the

UE in the SidelinkUEInformation message. This may allow the UE to reuse the same

RX/TX chain for both cellular communication and ProSe Discovery on the requested

ProSe discovery carrier. 2. Deactivate or deconfigure a serving cell in which the UE is currently performing cellular communication. This would allow the UE to release the RX/TX chain used for cellular communication.

The above actions 1, 2 may also be used to deconfigure a previously configured gap (i.e., upon reception of command for handover to the ProSe discovery carrier, or

deactivation/deconfiguration command of a serving cell, the eNB and the UE may implicitly release the previously configured gap without any further gap release signaling). Alternatively, actions 1 , 2 might trigger a signal to explicitly release the gap.

Similarly, if actions 1, 2 are taken by the eNB after reception of a gap request, the gap request is not accepted (i.e., gap not configured). Alternatively, the eNB may also send a signal to indicate that the gap request has not been accepted.

Operations of a wireless terminal UE will now be discussed with reference to the flow chart of Figure 8 and the modules of Figure 9. For example, modules of Figure 9 may be stored in wireless terminal memory 307 of Figure 7, and these modules may provide instructions so that when the instructions of a module are executed by wireless terminal processor 303, processor 303 performs respective operations of the flow chart of Figure 8. As shown in Figures 5 and 7, wireless terminal UE may communicate using transceiver 301 over a wireless interface with a base station BS of a Radio Access Network RAN.

The flow chart of Figure 8 illustrates wireless terminal UE operations using a first carrier and a second carrier different than the first carrier. At block 801, processor 303 may receive system information over the second carrier through transceiver 301 (e.g., using instructions of system information reception module 901), with the system information including a resource configuration identifying subframes of the second carrier available for device-to-device (D2D) operations. At block 803, processor 303 may compare subframes in which D2D operations should be performed with a discontinuous reception (DRX) pattern (e.g., using instructions of subframe comparison module 903).

At block 805, processor 303 may transmit a D2D gap request through transceiver 301 to a serving base station of a radio access network RAN (e.g., using instructions of D2D gap request transmission module 905), and the D2D gap request may include an identification of the second carrier and the resource configuration identifying subframes of the second carrier available for D2D operations. The D2D gap request, for example, may be transmitted responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of the DRX pattern. Moreover, the second carrier may be used by a second base station different than the first base station.

At block 807, processor 303 may receive D2D configuration information from the serving base station of the RAN through transceiver 301 using the first carrier as a serving carrier after receiving the system information and after transmitting the D2D gap request (e.g., using instructions of D2D configuration information reception module 907), with the D2D

configuration information being for the second carrier.

At block 809, processor 303 may perform D2D operations (through transceiver 301) using the second carrier based on the D2D configuration information for the second carrier (e.g., using D2D operations performance module 909). For example, processor 303 may perform D2D discovery operations using the second carrier based on the D2D configuration information for the second carrier.

According to some embodiments of Figure 8, receiving the system information at block 801 may include receiving the system information while engaged in cellular communications using the first carrier of the serving base station, responsive to determining that no

receiver/transmitter (RX/TX) chain is available for D2D operations using the second carrier, and before receiving the D2D configuration information from the base station at block 807.

Moreover, transmitting the D2D gap request at block 805 may include transmitting the D2D gap request responsive to determining a difference between the resource configuration of the system information from the second carrier and a previous resource configuration from the second carrier. In addition, transmitting the D2D gap request at block 805 may include transmitting the D2D gap request responsive to determining the difference between the resource configuration of the system information from the second carrier and the previous resource configuration from the second carrier, and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of a discontinuous reception DRX pattern.

According to some other embodiments of Figure 8, receiving the system information at block 801 may include receiving the system information while engaged in cellular

communications using the first carrier of the serving base station, responsive to determining that no receiver/transmitter (RX/TX) chain is available for D2D operations using the second carrier, and before receiving the D2D configuration information from the base station at block 807. Moreover, transmitting the D2D gap request at block 803 may include transmitting the D2D gap request responsive to the resource configuration of the system information from the second carrier being a first resource configuration received for the second carrier since entering a current connected mode with the serving base station. In addition, transmitting the D2D gap request at block 805 may include transmitting the D2D gap request responsive to the resource

configuration of the system information from the second carrier being a first resource configuration received for the second carrier since entering the current connected mode with the serving base station and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of a discontinuous reception, DRX, pattern.

Various operations of Figure 8 and/or modules of Figure 9 may be optional with respect to some embodiments of wireless terminals and related methods. Regarding methods of example embodiment 1 (set forth below), for example, operations of blocks 801, 803, and 805 of Figure 8 may be optional, and regarding related termination nodes, modules 901, 903, and 905 of Figure 9 may be optional. Regarding methods of example embodiment 2 (set forth below), for example, operations of block 803 of Figure 8 may be optional, and regarding related termination nodes, module 903 of Figure 9 may be optional. Regarding methods of example embodiment 10 (set forth below), for example, operations of block 801 of Figure 8 may be optional, and regarding related termination nodes, module 901 of Figure 9 may be optional.

Operations of a wireless terminal UE will now be discussed with reference to the flow chart of Figure 10 and the modules of Figure 11 according to some other embodiments. For example, modules of Figure 11 may be stored in wireless terminal memory 307 of Figure 7, and these modules may provide instructions so that when the instructions of a module are executed by wireless terminal processor 303, processor 303 performs respective operations of the flow chart of Figure 10. As shown in Figures 5 and 7, wireless terminal UE may communicate using transceiver 301 over a wireless interface with a base station BS of a Radio Access Network RAN.

The flow chart of Figure 10 illustrates wireless terminal UE operations using a first carrier and a second carrier different than the first carrier. At block 1003, processor 303 may compare subframes in which device-to-device (D2D) operations should be performed with a discontinuous reception (DRX) pattern (e.g., using instructions of subframe comparison module 1103).

Responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of the DRX pattern, processor 303 may transmit a D2D gap request through transceiver 301 to a serving base station of a radio access network RAN at block 1005 (e.g., using D2D gap request transmission module 1105). Moreover, the D2D gap request may include an identification of the second carrier and a resource configuration identifying subframes of the second carrier available for D2D operations.

After comparing subframes and after transmitting the D2D gap request, processor 303 may receive D2D configuration information from the serving base station of the RAN through transceiver 301 using the first carrier as a serving carrier at block 1007 (e.g., using D2D configuration information reception module 1107), with the D2D configuration information being for the second carrier. At block 1009, processor 303 may perform D2D operations using the second carrier based on the D2D configuration information for the second carrier (e.g., using D2D operations performance module 1109).

According to some embodiments of Figure 10, the second carrier may be used by a second base station different than the first base station, and/or performing D2D operations may include performing D2D discovery operations.

Various operations of Figure 10 and/or modules of Figure 11 may be optional with respect to some embodiments of wireless terminals and related methods.

Example Embodiments:

1. A method of operating a wireless terminal, the method comprising: receiving device- 2-device, D2D, configuration information from a serving base station of a radio access network using a first carrier as a serving carrier, wherein the D2D configuration information is for a second carrier different that the first carrier; and performing D2D operations using the second carrier based on the D2D configuration information for the second carrier.

2. The method of Embodiment 1 further comprising: before receiving the D2D configuration information from the serving base station, receiving system information over the second carrier including a resource configuration identifying subframes of the second carrier available for D2D operations; and before receiving the D2D configuration information from the serving base station, transmitting a D2D gap request to the serving base station wherein the D2D gap request includes an identification of the second carrier and the resource configuration identifying subframes of the second carrier available for D2D operations.

3. The method of Embodiment 2 further comprising: before transmitting the D2D gap request to the serving base station, transmitting a D2D notification to the serving base station including an identification of the second carrier.

4. The method of Embodiment 3 wherein the D2D notification is a

SidelinkUelnformation message.

5. The method of any of Embodiments 3-4 further comprising: before transmitting the D2D notification, receiving system information from the serving base station including a resource configuration identifying subframes of the first carrier available for D2D operations.

6. The method of Embodiment 1 further comprising: before receiving the D2D configuration information, transmitting a D2D notification to the serving base station, wherein the D2D notification includes an identification of the second carrier.

7. The method of Embodiment 6 wherein the D2D notification is a

SidelinkUelnformation message.

8. The method of any of Embodiments 6-7 further comprising: before receiving the D2D configuration information, transmitting a wireless terminal capability message to the serving base station, wherein the wireless terminal capability message defines a carrier aggregation capability of the wireless terminal.

9. The method of any of Embodiments 1-8 further comprising: after receiving the configuration information, receiving system information over the second carrier including a resource configuration identifying subframes of the second carrier available for D2D operations; and responsive to receiving the system information over the second carrier after receiving the configuration information, transmitting a gap change request to the serving base station using the first carrier wherein the gap change request includes an identification of the second carrier and the resource configuration identifying subframes of the second carrier available for D2D operation.

10. The method of any of Embodiments 1-9, further comprising: before receiving the D2D configuration information from the base station, comparing subframes in which D2D operations should be performed with a discontinuous reception, DRX, pattern; and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of the DRX pattern and before receiving the D2D configuration information from the base station, transmitting a D2D gap request to the serving base station wherein the D2D gap request includes an identification of the second carrier and a resource configuration identifying subframes of the second carrier available for D2D operations.

11. The method of any of Embodiments 1 -9, further comprising: before receiving the D2D configuration information from the base station and while engaged in cellular

communications using the first carrier of the serving base station, receiving system information over the second carrier including a resource configuration identifying subframes of the second carrier available for D2D operations responsive to determining that a no receiver/transmitter (RX/TX) chain is available for D2D operations using the second carrier; and responsive to determining a difference between the resource configuration of the system information from the second carrier and a previous resource configuration from the second carrier, transmitting a D2D gap request to the serving base station wherein the D2D gap request includes an identification of the second carrier and the resource configuration identifying subframes of the second carrier available for D2D operations.

12. The method of Claim 11 wherein transmitting the D2D gap request comprises transmitting the D2D gap request responsive to determining the difference between the resource configuration of the system information from the second carrier and the previous resource configuration from the second carrier, and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of a discontinuous reception, DRX, pattern.

13. The method of any of Embodiments 1-9, further comprising: before receiving the D2D configuration information from the base station and while engaged in cellular

communications using the first carrier of the serving base station, receiving system information over the second carrier including a resource configuration identifying subframes of the second carrier available for D2D operations responsive to determining that a no receiver/transmitter (RX/TX) chain is available for D2D operations using the second carrier; and responsive to the resource configuration of the system information from the second carrier being a first resource configuration received for the second carrier since entering a current connected mode with the serving base station, transmitting a D2D gap request to the serving base station wherein the D2D gap request includes an identification of the second carrier and the resource configuration identifying subframes of the second carrier available for D2D operations.

14. The method of Claim 13 wherein transmitting the D2D gap request comprises transmitting the D2D gap request responsive to the resource configuration of the system information received from the second carrier being a first resource configuration received for the second carrier since entering the current connected mode with the serving base station and responsive to collision between subframes in which D2D operations should be performed and DRX active mode subframes of a discontinuous reception, DRX, pattern.

15. The method of any of Embodiments 1 -14, the method further comprising: before receiving the D2D configuration information, evaluating conditions when to transmit a D2D gap request; and responsive to evaluating conditions when to transmit a D2D gap request, transmitting a D2D gap request to the serving base station wherein the D2D gap request includes an identification of the second carrier.

16. The method of Embodiment 15, wherein evaluating the conditions comprises evaluating radio capabilities to perform D2D operations, wherein transmitting the D2D gap request comprises transmitting the D2D gap request responsive to a result of said evaluation being that insufficient radio capabilities are available to perform for D2D operations.

17. The method of Embodiment 16 wherein the radio capabilities comprises a number of receiver chains of the wireless terminal that are available for D2D operations.

18. The method of Embodiment 16 wherein the radio capabilities comprises a number of transmitter chains of the wireless terminal that are available for D2D operations.

19. The method of Embodiment 15, wherein evaluating the conditions comprises detecting a new resource configuration identifying subframes of the second carrier to use for D2D operation, wherein transmitting the D2D gap request comprises transmitting the D2D gap request responsive to detecting the new resource configuration.

20. The method of Embodiment 15, wherein evaluating the conditions comprises detecting a resource configuration identifying subframes of the second carrier to use for D2D operation different than a resource configurations previously detected, wherein transmitting the D2D gap request comprises transmitting the D2D gap request responsive to detecting the resource configuration different than the resource configuration previously detected. 21. The method of Embodiment 15, wherein evaluating the conditions comprises selecting a new resource configuration identifying subframes of the second carrier to use for D2D operation, wherein transmitting the D2D gap request comprises transmitting the D2D gap request responsive to selecting the new resource configuration.

22. The method of Embodiment 15, wherein evaluating the conditions comprises selecting a resource configuration identifying subframes of the second carrier to use for D2D operation different than a resource configurations previously selected, and wherein transmitting the D2D gap request comprises transmitting the D2D gap request responsive to selecting the resource configuration.

23. The method of Embodiment 15, wherein evaluating the conditions comprises evaluating a DRX configuration together with a resource configuration identifying subframes of the second carrier to use for D2D operation, wherein transmitting the D2D gap request comprises transmitting the D2D gap request responsive to a result of said evaluation being that the subframes of the DRX configuration not indicating DRX on duration do not correspond to subframes of the resource configuration identifying subframes of the second carrier to use for D2D operation.

24. The method of Embodiment 15, wherein evaluating the conditions comprises evaluating a time transpired since a previous D2D gap request was transmitted, wherein transmitting the D2D gap request comprises transmitting the D2D gap request responsive to said time being longer than a threshold value.

25. The method of any of Embodiments 1-24 wherein the second carrier is used by a second base station different than the first base station.

26. The method of any of Embodiments 1-25 wherein performing D2D operations comprises performing D2D discovery operations.

27. The method of any of Embodiments 1-26 wherein performing D2D operations comprises performing D2D communication operations.

28. The method of any of Embodiments 1-27 wherein performing D2D operations comprises communicating directly between the wireless device and a second wireless device without communicating through the serving base station.

29. The method of any of Embodiments 1-28 wherein the first and second carriers are first and second frequency carriers. 30. The method of any of Embodiments 1-29 wherein the D2D configuration information identifies subframes banned from D2D operations.

31. The method of any of Embodiments 1-30 wherein the D2D configuration information identifies subframes allowed for D2D operations.

32. A method of operating a wireless terminal, the method comprising: evaluating conditions when to transmit a D2D gap request.

33. The method in Embodiment 32, wherein the conditions comprises evaluating radio capabilities to perform D2D operations; and the result of said evaluation being that insufficient radio capabilities are available to perform for D2D operations.

34. The method in Embodiment 33 wherein the radio capabilities comprises the number of receiver chains of the wireless terminal.

35. The method in Embodiment 33 wherein the radio capabilities comprises the number of transmitter chains of the wireless terminal.

36. The method in Embodiment 32, wherein the conditions comprises the detection of a new resource configuration identifying subframes of a carrier to use for D2D operation.

37. The method in Embodiment 32, wherein the conditions comprises the detection of a resource configuration identifying subframes of a carrier to use for D2D operation different than the resource configurations previously detected.

38. The method in Embodiment 32, wherein the conditions comprises the selection of a new resource configuration identifying subframes of a carrier to use for D2D operation.

39. The method in Embodiment 32, wherein the conditions comprises the selection of a resource configuration identifying subframes of a carrier to use for D2D operation different than the resource configurations previously selected.

40. The method in Embodiment 32, wherein the conditions comprises the evaluation of a DRX configuration together with a resource configuration identifying subframes of a carrier to use for D2D operation; and the result of said evaluation being that the subframes of the DRX configuration not indicating DRX on duration do not correspond to the subframes of the resource configuration identifying subframes of a carrier to use for D2D operation.

41. The method in Embodiment 32, wherein the conditions comprises evaluating the time transpired since a previous D2D gap request was transmitted; and said time being longer than a configured value. 42. A wireless terminal adapted to perform according to any of Embodiments 1-41.

43. A wireless terminal comprising: a transceiver configured to provide wireless communication with one or more nodes of a radio access network, RAN; and a processor coupled with the transceiver, wherein the processor is configured to perform operations according to any of Embodiments 1-41, and wherein the processor is configured to transmit and/or receive communications to/from the one or more nodes of the RAN through the transceiver.

ABBREVIATIONS

Abbreviation Explanation

D2D Device-to-Device Communication

ProSe Proximity Service

eNB eNodeB

LTE Long-Term Evolution

MAC Medium access control

PLMN Public land mobile network

RRC Radio resource control

UE User Equipment

V2I Vehicle-to-Infrastructure

V2P Vehicle-to-Pedestrian

V2V Vehicle-to-vehicle communication

V2x Vehicle-to-anything-you-can-imagine

RX Receiver

TX Transmitter

IEEE Institute of Electrical and Electronics Engineers

3 GPP Third Generation Partnership Project

DRX Discontinuous Reception

QoS Quality of Service

SIB System Information Block

MBSFN Multicast-broadcast single-frequency network

NSPS National Security Public Safety

Further Definitions: When an element is referred to as being "connected", "coupled", "responsive", or variants thereof to another element, it can be directly connected, coupled, or responsive to the other element or one or more intervening elements may be present. In contrast, when an element is referred to as being "directly connected", "directly coupled", "directly responsive", or variants thereof to another element, there are no intervening elements present. Like numbers refer to like nodes/elements throughout. Furthermore, "coupled", "connected", "responsive", or variants thereof as used herein may include wirelessly coupled, connected, or responsive. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Well-known functions or constructions may not be described in detail for brevity and/or clarity. The term "and/or", abbreviated "/", includes any and all combinations of one or more of the associated listed items.

As used herein, the terms "comprise", "comprising", "comprises", "include", "including", "includes", "have", "has", "having", or variants thereof are open-ended, and include one or more stated features, integers, nodes, steps, components or functions but do not preclude the presence or addition of one or more other features, integers, nodes, steps, components, functions or groups thereof. Furthermore, as used herein, the common abbreviation "e.g.", which derives from the Latin phrase "exempli gratia," may be used to introduce or specify a general example or examples of a previously mentioned item, and is not intended to be limiting of such item. The common abbreviation "i.e.", which derives from the Latin phrase "id est," may be used to specify a particular item from a more general recitation.

It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements/operations, these elements/operations should not be limited by these terms. These terms are only used to distinguish one element/operation from another

element/operation. Thus a first element/operation in some embodiments could be termed a second element/operation in other embodiments without departing from the teachings of present inventive concepts. Examples of embodiments of aspects of present inventive concepts explained and illustrated herein include their complimentary counterparts. The same reference numerals or the same reference designators denote the same or similar elements throughout the specification.

Example embodiments are described herein with reference to block diagrams and/or flowchart illustrations of computer-implemented methods, apparatus (systems and/or devices) and/or computer program products. It is understood that a block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions that are performed by one or more computer circuits. These computer program instructions may be provided to a processor circuit (also referred to as a processor) of a general purpose computer circuit, special purpose computer circuit, and/or other programmable data processing circuit to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, transform and control transistors, values stored in memory locations, and other hardware components within such circuitry to implement the functions/acts specified in the block diagrams and/or flowchart block or blocks, and thereby create means (functionality) and/or structure for implementing the functions/acts specified in the block diagrams and/or flowchart block(s).

These computer program instructions may also be stored in a tangible computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions which implement the functions/acts specified in the block diagrams and/or flowchart block or blocks.

A tangible, non-transitory computer-readable medium may include an electronic, magnetic, optical, electromagnetic, or semiconductor data storage system, apparatus, or device. More specific examples of the computer-readable medium would include the following: a portable computer diskette, a random access memory (RAM) circuit, a read-only memory (ROM) circuit, an erasable programmable read-only memory (EPROM or Flash memory) circuit, a portable compact disc read-only memory (CD-ROM), and a portable digital video disc readonly memory (DVD/BlueRay).

The computer program instructions may also be loaded onto a computer and/or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer and/or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the block diagrams and/or flowchart block or blocks. Accordingly, embodiments of present inventive concepts may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.) that runs on a processor such as a digital signal processor, which may collectively be referred to as "circuitry," "a module" or variants thereof.

It should also be noted that in some alternate implementations, the functions/acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality /acts involved. Moreover, the functionality of a given block of the flowcharts and/or block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts and/or block diagrams may be at least partially integrated. Finally, other blocks may be added/inserted between the blocks that are illustrated. Moreover, although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, the present specification, including the drawings, shall be construed to constitute a complete written description of various example combinations and

subcombinations of embodiments and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

Other network elements, communication devices and/or methods according to embodiments of inventive concepts will be or become apparent to one with skill in the art upon review of the present drawings and description. It is intended that all such additional network elements, devices, and/or methods be included within this description, be within the scope of the present inventive concepts. Moreover, it is intended that all embodiments disclosed herein can be implemented separately or combined in any way and/or combination.