COMMUNICATIONS SYSTEM

TECHNICAL FIELD

The present invention relates to cell selection in mixed cellular and device-to-device communication networks. More particularly, the present invention relates to a cell 5 manager, a user equipment and methods of assisting a cell selection procedure of a user equipment in a system comprising cell managers controlling cells providing different types of connectivity.

BACKGROUND

The Universal Mobile Telecommunication System (UMTS) is one of the third generation

10 mobile communication technologies designed to succeed GSM. 3GPP Long Term Evolution (LTE) is a project within the 3 ^rd Generation Partnership Project (3GPP) to improve the UMTS standard to cope with future requirements in terms of improved services such as higher data rates, improved efficiency, lowered costs etc. The Universal Terrestrial Radio Access Network (UTRAN) is the radio access network of a UMTS and

15 Evolved UTRAN (E-UTRAN) is the radio access network of an LTE system. In an E- UTRAN, a user equipment (UE) 150 is wirelessly connected to a radio base station (RBS) 110a-c commonly referred to as an eNodeB or eNB (E-UTRAN NodeB), as illustrated in Figure 1a. The eNBs 110a-c are directly connected to the core network (CN) 190. The CN 190 to which an E-UTRAN is connected is called the Evolved Packet Core (EPC),

20 a.k.a. the System Architecture Evolution (SAE) network. The E-UTRAN and the EPC form together the Evolved Packet System (EPS) also known as the SAE/LTE network. The standard specifications for SAE/LTE also include the possibility of having an E-UTRAN RBS providing home or small area coverage for a limited number of users. Such a home or small area coverage RBS is hereinafter called a Home eNodeB (HeNB). For UTRAN

25 (UMTS), this type of home access point is called Home NodeB (HNB).

Before a UE can transmit or receive information to/from an E-UTRAN, it must search for and select an appropriate serving cell, and perform random access in the selected cell. These steps together are often referred to as the "initial access" procedure and enable a UE to obtain synchronization and fundamental system parameters, and to get access to 30 the system resources for the connection. The UE synchronizes both in time and frequency to the so called primary and secondary synchronization signals (PSS and SSS) that together encode the different E-UTRAN cells' physical layer cell identity (abbreviated PHY Cell ID, PCI or PID). A PCI is composed of the PCI group (with a value between 0 and 167) and the physical layer identity (0, 1 or 2), allowing currently for 504 different PCI values. The PSS and SSS are constructed in a way that makes it possible for a UE to find and read these synchronization signals, e.g. after powering up the UE, and thereby to decode the PCI.

Cell selection is a process in the radio resource layers in the UE that is normally performed at initial power-on of the UE and without guidance from the network. It is traditionally preceded by a Public Land Mobile Network, PLMN, selection procedure in the upper layers in the UE, meaning that the radio resource layers only search for cells belonging to the selected PLMN. The purpose of cell selection is to find a suitable cell to camp on that becomes the serving cell for the UE. While camping on a serving cell, the UE regularly checks if there exists a better cell to camp on and this process is called cell reselection. Cell reselection is also part of the radio resource layer process in the UE and is typically performed in idle mode, but may for example in UMTS also apply to some other modes. The cell reselection process is normally based on measurements of signals received from the cells, and on the system information read in the best ranked cell ensuring that the UE is allowed to access that cell. Hereinafter, the term "cell selection" is used both for cell selection and cell reselection, and/or the like. During the cell selection procedure, the UE is able to decode the physical broadcast channel and read the so called master information block (MIB). The MIB contains essential system information, such as the system bandwidth and the number of transmit antennas at the eNB side, i.e. information needed for the UE to be able to communicate with the LTE network. After having decoded the MIB the UE has enough information to decode the system information blocks (SIBs) transmitted on the downlink shared channel (DL-SCH). There are multiple SIBs numbered from one and upwards. Among these SIBs, SIB1 and SIB2 are essential for accessing the system and begin uplink transmission. SIB1 and SIB2 comprises information about the configuration of the different radio channels in the cell, such as physical uplink control channel (PUCCH), and random access channel (RACH), as well as cell barring information.

Eventually, the random access (RA) procedure, which is illustrated in Figure 2, is used to obtain or to re-establish uplink synchronization and an initial grant to uplink transmission resources. The UE 250 transmits the RA preamble in 201 to the eNB 210 in order to obtain uplink synchronization prior to any transmission of user data. The eNB 210 sends a RA response in 202 to the UE 250 that e.g. contains a time alignment instruction as well as the initial physical uplink shared channel (PUSCH) resource grant. The information in 5 the RA response allows the UE 250 to transmit uplink data and/or signalling, and the UE 250 and the eNB 210 are able to communicate with each other controlled by dedicated signalling over the downlink shared channel (DL-SCH). The UE may subsequently request an RRC connection in 203 and eventually receives a dedicated RRC connection setup message from the eNB in 204.

10 Device-to-device (D2D) communication has been promoted as a means to provide peer- to-peer services between UEs, to facilitate infrastructure-less communications in emergency, as well as national security and public safety (NSPS) situations, and to enhance network capacity by off-loading traffic from the radio access network. A design option for implementing D2D communication between LTE UEs is to adopt the Bluetooth

15 master-slave concept. While maintaining most of the E-UTRAN protocols one of the communicating UEs take the master role and closely emulates an eNB. Such a design is illustrated in Figure 1b, in which the Master UE 140 provides PSS and SSS, as well as the essential system information (MIB and some of the SIBs such as SIB1&2) to the Slave UE 150. The Master UE 140 also implements the standard RA procedure in the same way

20 as a regular cellular eNB. The Slave UE 150 may thus apply a similar initial access to the Master UE 140 as to a regular eNB. However, although the eNB emulation makes the Master UE 140 appear as a "real" eNB, there are also some significant differences that are not transparent to the Slave UE 150. For example, the services provided by a Master UE 140 are largely different than services provided by a regular eNB, since the Master UE

25 140 may not even be connected to a mobile network.

The increasing demand for indoor service coverage has triggered the standardization of the home base stations (HeNB for LTE/SAE and HNB for UMTS) both by the 3GPP and the IEEE communities. Although a HeNB provides similar basic functionalities to an LTE UE, it may differ from a regular macro eNB in terms of output transmit power, mobility 30 support, access control, and to some extent also in terms of the provided services. Some examples of the differences are that a handover to/from HeNB may not be transparent for the end user, and that a HeNB needs to handle closed subscriber groups (CSG) in order to limit the access to the HeNB. Figure 1c illustrates schematically a mixed radio environment, comprising different types of so called cell managers. A cell manager may e.g. be a eNB 120a-b, a HeNB 130a, or any other kind of RBS in a cellular system connected to a CN 190, which in turn may be connected to the Internet 191. However, a cell manager may also be a Master UE 140a-b closely emulating a regular eNB as described above, or any other device that announces communication services to UEs. A Master UE is not always connected to the mobile network, as the Master UE 140b shown in Figure 1c. Furthermore, a HeNB may in the future not need to be connected to the CN 190 for the user plane connectivity, but may e.g. be connected to the Internet 191 via an Internet Service Provider (ISP) 192, as shown for HeNB 130b, or only to a local area network (LAN) 193, as shown for HeNB 130c. Such an evolved HeNB 130b-c thus provides a local network connectivity and/or Internet connectivity within the coverage area, but no CN connectivity. To summarize, a cell manager will thus control some kind of "cell", which in the case of a eNB 120a-b and a HeNB 130a-c is the cell corresponding to the coverage area of the eNB or HeNB. In the case of a Master UE 140a-b, the cell is the coverage area of the Master UE from the perspective of potential Slave UEs 150. Such cells may overlap more significantly than cells in traditional cellular networks, since there is no regular geometrical pattern of the Master UEs providing the radio resources of the cell.

In such a mixed radio environment, a UE may thus find a number of candidate "cells" controlled by different types of cell managers including eNBs, HeNBs, evolved HeNBs, and Master UEs closely emulating an eNB. This may slow down the cell selection procedure, and may also increase the power consumption in the UE.

SUMMARY

The object of the present invention is to address some of the problems and disadvantages outlined above, and to assist the cell selection of a UE in a mixed radio environment comprising cell managers controlling cells providing different kinds of connectivity. This object and others are achieved by the methods and devices according to the independent claims, and by the embodiments according to the dependent claims.

In accordance with a first aspect of the present invention, a method for assisting a cell selection procedure of a user equipment, in a cell manager controlling a cell is provided. The method comprises transmitting information comprising an indicator of the connectivity provided in the cell to the user equipment, in order for the user equipment to determine a cell capability based on the transmitted information. In accordance with a second aspect of the present invention, a method in a user equipment of a cellular system for assisting a cell selection procedure is provided. The cellular system comprises cell managers controlling cells providing different types of connectivity. The method comprises receiving information from the cell manager, the information comprising an indicator of the connectivity provided in a cell controlled by the cell manager, and determining a capability of the cell controlled by the cell manager based on the received information, for each of at least one cell manager.

In accordance with a third aspect of the present invention, a cell manager is provided. The cell manager is adapted to control a cell, and to assist a cell selection procedure of a user equipment. It comprises a transmitter unit adapted to transmit information comprising an indicator of the connectivity provided in the cell to the user equipment, in order for the user equipment to determine a cell capability based on the transmitted information.

In accordance with a fourth aspect of the present invention, a user equipment for a cellular system comprising cell managers controlling cells providing different types of connectivity is provided. The user equipment is adapted to assist a cell selection procedure, and comprises a receiver unit adapted to receive information from at least one cell manager. The information comprises an indicator of the connectivity provided in a cell controlled by the cell manager. The user equipment also comprises a determining unit adapted to determine a capability of the cell controlled by the cell manager based on the received information.

An advantage of embodiments of the present invention is that they allow the UE to distinguish between cells controlled by different types of cell managers and to detect the capabilities of these cells early during the different steps of the initial access procedure without requiring extensive changes in the procedure. This speeds up the scanning of available devices for e.g. D2D communication and reduces the UE power consumption.

A further advantage of embodiments of the present invention is that they allow a smooth integration of D2D communication, local access HeNBs and other cell managers into a cellular system such as the LTE network.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1a illustrates schematically a part of a conventional wireless communication system. Figure 1 b illustrates schematically D2D communication between a Master UE emulating an eNB and a Slave UE.

Figure 1c illustrates a mixed radio environment comprising cell managers controlling cells of different types of cells, wherein the present invention may be implemented. Figure 2 is a signalling diagram illustrating the random access and the RRC connection establishment between an eNB and a UE according to prior art.

Figure 3 is a flowchart of the method performed by the cell manager according to embodiments of the present invention.

Figure 4 is a flowchart of the method performed by the UE according to embodiments of the present invention.

Figure 5 illustrate schematically a cell manager and a UE according to embodiments of the present invention.

Figure 6 illustrate schematically a UE according to embodiments of the present invention. DETAILED DESCRIPTION In the following, the invention will be described in more detail with references to certain embodiments and to accompanying drawings. For purposes of explanation and not limitation, specific details are set forth, such as particular scenarios, techniques, etc., in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practised in other embodiments that depart from these specific details.

Moreover, those skilled in the art will appreciate that the functions and means explained herein below may be implemented using software functioning in conjunction with a programmed microprocessor or general purpose computer, and/or using an application specific integrated circuit (ASIC). It will also be appreciated that while the current invention is primarily described in the form of methods and devices, the invention may also be embodied in a computer program product as well as in a system comprising a computer processor and a memory coupled to the processor, wherein the memory is encoded with one or more programs that may perform the functions disclosed herein.

The present invention is described herein by way of reference to particular example scenarios. In particular embodiments of the invention are described in a non-limiting general context in relation to an E-UTRAN. It should though be noted that the invention and its exemplary embodiments may also be applied to other types of radio access networks allowing different kinds of cell managers in a mixed radio environment, such as D2D communication in the radio access network.

In a mixed radio environment such as the one illustrated in Figure 1c, a UE may thus find a number of candidate "cells" controlled by different types of cell managers including eNBs, HeNBs, evolved HeNBs, and Master UEs closely emulating an eNB. Conventionally, the UE is not aware of the specific characteristics and limitations that the different cells may have during the initial access procedure. In particular it is not aware of what services that are offered in the respective cells, such as local services in a home or small office or global connectivity provided by a mobile operator's CN. A Master UE emulating an eNB may e.g. not even be connected to the CN and thus offers services that are completely different from those provided by a regular eNB. The UE scanning its radio environment and detecting available "cells" in this type of mixed environment has the problem that it cannot know what cells that are suitable for its communication needs, as it does not know what connectivity and services a cell provides. This may slow down the cell selection procedure as it may take a number of tries before a suitable cell is found. This may also increase the power consumption in the UE. In embodiments of the present invention, the problem of the reduced efficiency of the cell selection procedure for a UE in a mixed radio environment, is addressed by a solution where the cell manager transmits information indicating the connectivity and possibly also the services provided by the cell(s) it controls. The cell manager may e.g. be a regular eNB 120a-b, a HeNB 130a or evolved HeNB 130b-c, or a Master UE 140a-b. The indicator of the provided connectivity/services is comprised in the synchronization signals, and/or in the master and system information blocks MIB/SIB, and/or in the RA response or in other dedicated signalling used by the cell managers. The accessing UE may thereby receive information about the connectivity of the cell and the provided services at an early stage of the initial access. This information may help the UE to determine a cell capability and to decide on further actions, e.g. if it should continue the access procedure in a specific cell, scan for other cells, provide a report to application programs and/or to the end user, or any other combination of these actions. The initial access procedure as performed by regular UEs and eNBs remains unchanged according to embodiments of the invention. Embodiments of the present invention will in the following be described with reference to the example scenario schematically illustrated in Figure 1c. One of the HeNBs 130a and one of the Master UEs 140a are connected to an operator's CN 190. However, the other Master UE 140b is standalone (i.e. without any network connection), and one other evolved HeNB 130b is connected to an Internet Service Provider (ISP) network 192 rather than to the CN 190. Furthermore, another evolved HeNB 130c provides only a local connectivity as it is connected to a LAN 193 and not to the CN 190. These different kinds of so called cell managers may according to embodiments of the invention transmit information to the UEs comprising an indicator of the connectivity provided in the cell or cells controlled by the cell manager. The indicator may in embodiments of the present invention indicate either no connectivity (e.g. for the standalone Master UE) or any combination of a CN connectivity, a local network connectivity, and an Internet connectivity.

In another embodiment, the information transmitted to the UEs also comprises an indicator of the services provided in the cell controlled by the cell manager.

In a first embodiment of the present invention the information comprising the indicator of the provided connectivity and possibly also the indicator of the provided services is transmitted in the primary and/or in the secondary synchronization signals (PSS/SSS). This allows UEs that read the downlink PSS/SSS to detect the cell manager type and also the services provided by a cell at a very early stage of the initial access procedure.

In this first embodiment, the type or category of the cell manager controlling the cell and transmitting the PSS/SSS may be indicated, which may implicitly indicate the connectivity and the services provided by the cell. One implementation of the first embodiment is to create special cell identities (PCIs) to explicitly indicate whether the cell manager is e.g. a HeNB or a Master UE. One concrete solution is to let the cell manager use special PCI groups that are encoded in the SSS to indicate that the cell manager is a HeNB or a Master UE. Another solution is to reserve special PCIs or PCI ranges to directly indicate the connectivity provided in the cell i.e. to indicate either no connectivity or any combination of a CN connectivity, a local network connectivity, or an Internet connectivity. One way to achieve this would be to extend the current PCI numbering space from the current 504 different values to a larger numbering space to allow additional indications using PCI. Numbering space for further cell manager types such as the evolved HeNB may be reserved for future use. The following example illustrates how the PCI groups may be distributed between the cell managers according to one embodiment of the present invention (in this example the PCI group range has been extended from the current range of from 0 to 167 to a range of from 0 to 255):

- PCI group 0-167: Used for cell managers controlling regular eNB cells

- PCI group 168...199: Used for cell managers controlling HeNB cells

- PCI group 200...255: Used for cell managers controlling Master UE cells

It is of course also possible to sub-divide the groups further by having different ranges of PCI groups for different types of Master UEs e.g., such as printers and smartphones.

In LTE, the MIB and the SIBs are broadcasted with different periodicity. MIB and SIB1 are scheduled in fixed positions. SIB2 and upwards are scheduled in a flexible way in so called System Information (SI) windows. The SI windows are scheduled in predefined radio frames identified by their respective system frame numbers (SFN). The MIB that contains the most essential parameters is scheduled to be broadcasted every 40 ms, while for example SIB1 containing cell access and scheduling related information is scheduled every 80 ms.

In a second embodiment of the present invention, information about the type and capabilities of the cell manager can be provided by extending the broadcasted MIB and some of the SIBs with information indicating the provided connectivity and the provided services. This information supports the UE in the decision whether it wants to start camping on the cell and attempt a random access in the cell. Since broadcasting the MIB is resource consuming, the MIB should be restricted to the most essential pieces of information (in the current LTE standard the MIB uses 14 bits out of 24 transmitted bits). Likewise, the lower numbered SIBs should also contain only limited information.

The following are some examples of what SI block that may comprise the information (bullet 1 and 2 below) and what the information may indicate (sub-bullets below) with regards to connectivity and services provided in the corresponding cell according to this second embodiment:

1. Additional bits in the MIB in a cell controlled by e.g. an eNB, a HeNB or a Master UE indicating: - Cell manager providing either no connectivity or any combination of a CN connectivity, a local network connectivity, or an Internet connectivity (requires 3 extra bits in MIB).

2. Additional bits in SIB1 in a cell controlled by e.g. a HeNB or a Master UE indicating:

- HeNB or Master UE capabilities in terms of maximum transmit power and supported bandwidth;

- Other supported services such as a printing service, a COM port emulation, and/or a file transfer service; - Information about the cell manager name e.g. an identity, a name, and/or an owner. This is similar to the field hnb-Name, which is currently sent in SIB9.

Note that the so called 'additional bits' includes extension of existing information elements. The 'PLMN Identity list' could e.g. be extended so that specific PLMN identities indicate local services or access via an ISP. During the RA procedure between an eNB 210 and a UE 250, schematically illustrated in Figure 2, the eNB transmits a RA response in 202 as a reply to the UE's transmission of a RA preamble in 201. In the state of the art, the RA response in 202 may e.g. contain the following information:

- Time alignment information - Initial PUSCH resource grant

- Power control command for the uplink

- Cell Radio Network Temporary Identifier (C-RNTI)

In a third embodiment of the present invention, the RA response in 202 is extended to include information from the cell manager comprising indicators of the connectivity and possibly also of the services provided by the cell controlled by the cell manager. Examples of such indicators in the RA response are:

- An indicator of the supported higher layer protocols which may be relevant in the case of a Master UE, such as IPv4, IPv6, TCP, UDP, and SIP.

- An indicator of the provided service types, such as file exchange (download), streaming services, and real time services.

In addition to including the information in the RA response, or as an alternative, the information may be provided in other dedicated signalling messages such as the RRC connection setup (in 204 of Figure 2). Still another example (not shown in Figure 2) would be to include the information as part of Non-Access Stratum (NAS) related signalling towards the UE. NAS signalling is normally performed between the UE and the CN, but in some cases the NAS signalling could also be emulated from the RAN towards the UE. Examples of NAS related signalling messages towards the UE are Attach Accept and Tracking Area Update Accept.

The first, second, and third embodiments described above may be combined in any possible way. The information comprising the indicators of the provided connectivity and services may e.g. be transmitted in the synchronization signals only. Alternatively it may be distributed in both the synchronization signals and in the SI, where e.g. the synchronization signals carry the indicator of the provided connectivity and the SIBs carry the indicators of the services provided in the cell. In still another alternative, the RA response is used to carry indicators of the connectivity and the services provided in the cells, possibly in combination with the SSS and/or a SIB. Figure 3 is a flowchart of the method performed by the cell manager according to embodiments of the present invention. The cell manager controls at least one cell, and the method assists the cell selection procedure that the UE performs. The method comprises transmitting 310 information to a UE, where the information comprises an indicator of the connectivity provided in the cell. By providing this information to the UE, the UE may determine a cell capability - in this case the connectivity provided by the cell - based on the information.

The indicator of the connectivity may in embodiments of the present invention indicate at least one of a core network connectivity, a local network connectivity, and an internet connectivity, or it may indicate that the cell does not provide any connectivity to a network at all. A Master UE which does not have a connection to an eNB and the CN, may e.g. not provide any network connectivity. The transmitted information may in another embodiment also comprise an indicator of the services provided in the cell. The Master UE that does not provide any network connectivity as the one mentioned above, may e.g. indicate that it provides D2D downloading of files. In embodiments of the invention, the information is transmitted in at least one of a synchronization signal, a MIB, a SIB, or a dedicated message, where the dedicated message may be a RA response message, and/or a RRC message, as described above with reference to the first, second and third embodiments.

Figure 4 is a flowchart of the method performed by the UE according to embodiments of the present invention. The method comprises the following:

- 410: Receive information from at least one cell manager. The information comprises an indicator of the connectivity provided in one or more cells controlled by the cell manager. The indicator indicates either that no connectivity is provided or that at least one of a core network connectivity, a local network connectivity, and an internet connectivity is provided. In another embodiment, the received information may further comprise one or more indicators of the services provided in the cell. The information may be received in a synchronization signal, a MIB, a SIB, or in a dedicated message such as a RA response message, and a RRC message, or in any combination of these signals and messages, as described above with reference to the first, second and third embodiments.

- 420: Determine a capability of the cell(s) for each of the cell managers based on the received information. This may be the connectivity capability and possibly also the service capability depending on what indicators that are comprised in the received information.

In a further embodiment of the present invention, the UE selects 430 one of the cell manager cells based on the determined cell capability. The UE may e.g. select the cell that provides the connectivity and the services that corresponds the best to its needs. Alternatively, the UE may provide the end user with information about the determined cell capabilities, and thereby letting the end user make the cell selection.

The cell manager 100 and the UE 150 are schematically illustrated in Figure 5, according to embodiments of the present invention. The cell manager 100 comprises a transmitter unit 101 adapted to transmit information comprising an indicator of the connectivity provided in the cell to the UE 150, in order for the UE to determine a cell capability based on the transmitted information. The indicator of the connectivity may indicate that no connectivity is provided or that one or more of a CN connectivity, a local network connectivity, and an internet connectivity is provided. The transmitter unit 101 may in one embodiment be adapted to transmit information comprising not only an indicator of the provided connectivity, but also an indicator of the services provided in the cell. The transmitter unit 101 may also be adapted to transmit the information in a synchronization signal, a MIB, a SIB, and/or a dedicated message such as a RA response message, and/or a RRC message, as described above with reference to the first, second and third embodiments.

The UE 150 comprises a receiver unit 151 adapted to receive information from one or more cell managers. The information comprises an indicator of the connectivity provided in a cell controlled by the cell manager. The UE 150 also comprises a determining unit 152 adapted to determine a capability of the cell for each of the cell managers based on the received information. In one further optional embodiment, the UE also comprises a cell selecting unit 153 adapted to select one of the cells based on the determined cell capability. The indicator may in one embodiment indicate that no connectivity is provided, or that one of a core network connectivity, a local network connectivity, or an internet connectivity is provided. The receiver unit 151 is in one embodiment adapted to receive information which further comprises an indicator of the services provided in the cell, and may also be adapted to receive the information comprising the indicators in one of a synchronization signal, a MIB, a SIB, and a dedicated message such as a RA response message, and/or a RRC message, or in any combinations of these signals and messages, as described above with reference to the first, second and third embodiments. The units described above with reference to Figure 5 are logical units and do not necessarily correspond to separate physical units.

Figure S schematically illustrates an embodiment of the UE 150, which is an alternative way of disclosing the embodiment illustrated in Figure 5. The UE 150 comprises a processing unit 154 which may be a single unit or a plurality of units. The UE 150 also comprises the receiver unit 151 for receiving the information from the cell managers comprising at least an indicator of the connectivity provided in a cell controlled by the cell manager as already discussed above. Furthermore, the UE 150 comprises at least one computer program product 155 in the form of a non-volatile memory, e.g. an EEPROM, a flash memory and a disk drive. The computer program product 155 comprises a computer program 156, which comprises code means which when run on the UE 150 causes the processing unit 154 on the UE 150 to perform the steps of the procedures described earlier in conjunction with Figure 4. Hence in the embodiments described, the code means in the computer program 156 of the UE 150 comprises a determining module 156a for determining a capability of one or more cells controlled by the cell manager based on the information received from that cell manager comprising an indicator of the connectivity provided in the cell(s), and a cell selecting module 156b for selecting one of the cells controlled by the cell manager based on the determined cell capability. The code means may thus be implemented as computer program code structured in computer program modules. The modules 156a-b essentially perform the steps of the flow in Figure 4 to emulate the UE described in Figure 5. In other words, when the different modules 156a-156b are run on the processing unit 154, they correspond to the units 152 and 53 of Figure 5.

Although the code means in the embodiment disclosed above in conjunction with Figure 6 are implemented as computer program modules which when run on the UE 150 causes the UE to perform steps described above in the conjunction with figures mentioned above, one or more of the code means may in alternative embodiments be implemented at least partly as hardware circuits.

The above mentioned and described embodiments are only given as examples and should not be limiting to the present invention. Other solutions, uses, objectives, and functions within the scope of the invention as claimed in the accompanying patent claims should be apparent for the person skilled in the art.

ABBREVIATIONS

3GPP 3rd Generation Partnership Program

AP Access Point

CN Core Network

CSG Closed Subscriber Group

D2D Device-to-Device

DL-SCH Downlink Shared Channel eNB Evolved Node B

EPC Evolved Packet Core

E-UTRAN Evolved UTRAN

HeNB Home eNodeB

HNB Home NodeB

IPv4/v6 Internet Protocol version 4/6

LTE Long Term Evolution

IB Master Information Block

NAS Non-Access Stratum

PCI Physical Layer Cell identity

PHY Cell ID Physical Layer Cell identity

PID Physical Layer Cell identity PLMN Public Land Mobile Network

PSS Primary Synchronization Signal PUCCH Physical Uplink Control Channel

PUSCH Physical Uplink Shared Channel

RA Random Access

RACH Random Access Channel

RAN Radio Access Network

RBS Radio Base Station

RRC Radio Resource Control

SAE System Architecture Evolution

SIB System Information Block

SIP Session Initiation Protocol

SSS Secondary Synchronization Signal

TCP Transmission Control Protocol

UDP User Datagram Protocol

UE User Equipment

UMTS Universal Mobile Telecommunications System

UTRAN Universal Terrestrial RAN

WLAN Wireless Local Area Network