ACCESS PROCEDURE

BACKGROUND

[0001] Wireless mobile communication technology uses various standards and protocols to transmit data between a node (e.g., a transmission station) and a wireless device (e.g., a mobile device). Some wireless devices communicate using orthogonal frequency-division multiple access (OFDMA) in a downlink (DL) transmission and single carrier frequency division multiple access (SC-FDMA) in uplink (UL). Standards and protocols that use orthogonal frequency-division multiplexing (OFDM) for signal transmission include the third generation partnership project (3GPP) long term evolution (LTE) Release 8, 9, 10, 11, 12 and 13, the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard (e.g., 802.16e, 802.16m), which is commonly known to industry groups as WiMAX (Worldwide interoperability for Microwave Access), and the IEEE 802.11 standard, which is commonly known to industry groups as WiFi.

[0002] In 3GPP radio access network (RAN) LTE systems (e.g., Release 13 and earlier), the node can be a combination of Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node Bs (also commonly denoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs) and Radio Network Controllers (RNCs), which communicates with the wireless device, known as a user equipment (UE). The downlink (DL) transmission can be a communication from the node (e.g., eNodeB) to the wireless device (e.g., UE), and the uplink (UL) transmission can be a communication from the wireless device to the node.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Features and advantages of the disclosure will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the disclosure; and, wherein:

[0004] FIG. 1 illustrates random access procedures between multiple user equipments (UEs) and a base station in accordance with an example;

[0005] FIGS. 2 to 6 illustrates performances for power based contention resolution techniques in accordance with an example;

[0006] FIG. 7 illustrates a system architecture for supporting wearable devices in accordance with an example;

[0007] FIG. 8 depicts functionality of a first user equipment (UE) operable to perform power based contention resolution between the first UE and a second UE during a random access procedure in accordance with an example;

[0008] FIG. 9 depicts functionality of a base station operable to perform a random access procedure for a first user equipment (UE) and a second UE in accordance with an example;

[0009] FIG. 10 depicts a flowchart of a machine readable storage medium having instructions embodied thereon for performing power based contention resolution between a first user equipment (UE) and a second UE during a random access procedure in accordance with an example;

[0010] FIG. 11 illustrates a diagram of a wireless device (e.g., UE) and a base station (e.g., eNodeB) in accordance with an example; and

[0011] FIG. 12 illustrates a diagram of a wireless device (e.g., UE) in accordance with an example.

[0012] Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the technology is thereby intended.

DETAILED DESCRIPTION

[0013] Before the present technology is disclosed and described, it is to be understood that this technology is not limited to the particular structures, process actions, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular examples only and is not intended to be limiting. The same reference numerals in different drawings represent the same element. Numbers provided in flow charts and processes are provided for clarity in illustrating actions and operations and do not necessarily indicate a particular order or sequence.

EXAMPLE EMBODIMENTS

[0014] An initial overview of technology embodiments is provided below and then specific technology embodiments are described in further detail later. This initial summary is intended to aid readers in understanding the technology more quickly but is not intended to identify key features or essential features of the technology nor is it intended to limit the scope of the claimed subject matter.

[0015] In one example, a user equipment (UE) can perform a random access procedure in order to access a network. In previous solutions, the random access procedure can include four steps. In Step 1, the UE can send a preamble to an eNodeB. In Step 2, the eNodeB can send a random access response to the UE. The random access response can include a temporary cell radio network temporary identity (C-RNTI), a timing advance value and an uplink grant resource. In Step 3, the UE can send a connection request message to the eNodeB. The connection request message can include a temporary mobile subscriber identity (TMSI) and a connection establishment cause. In Step 4, the eNodeB can send a contention resolution message to the UE. The contention resolution message can include a new C-RNTI to be used for subsequent communications by the UE.

[0016] In one example, in previous solutions, a relatively large number of UEs in the same cell can request to perform random access at the same time, and as a result, requests from the UEs can collide with each other. For example two UEs can send the same preamble at the same time to the eNodeB. As a result, a same temporary C-RNTI and uplink grant can be received by the two UEs from the eNodeB. The eNodeB may only receive a connection request message from one UE or neither of the two UEs due to interference. A UE that does not receive the contention resolution message from the eNodeB can perform a back-off after expiration of random access channel (RACH) specific timers. A UE that does receive the contention resolution message can

subsequently decode a radio resource control (RRC) connection setup message received from the eNodeB. When there is a possibility of collisions among the requests from the UEs, this random access procedure is referred to as a contention based random access procedure. In another example, the eNodeB can instruct the UE to use a unique identity, which can prevent its request from colliding with requests from other UEs. In this example, the random access procedure can be referred to as a non-contention based random access procedure.

[0017] In one example, in previous solutions, the random access procedure is limited to a defined number of preambles. Due to the increasing numbers of UE that attempt to connect to the network via the random access procedure, there is an increased risk that more than one UE will send the same preamble on the same random access channel (e.g., same time and frequency), thereby causing a collision. Using previous solutions, this collision can be resolved using contention resolution (e.g., after message 4), which is based on a timing advance and the UE's random identifier (ID). In previous solutions, all of the colliding UEs can perform signaling for messages 1 to 4 prior to the contention resolution, which can consume the limited energy at the UE.

[0018] In the present technology, a colliding UE can determine whether it has permission to access the network during the random access procedure (e.g., after message 2). The colliding UE can make the determination using the colliding UE's channel gain. By determining the permission to access the network earlier in the random access procedure (e.g., after message 2 as opposed to after message 4, as in previous solutions), energy consumption at the colliding UE can be reduced. In addition, the likelihood of message collision in a subsequent step of the random access procedure can be reduced. More specifically, the colliding UE can utilize power based contention resolution (after message 2) to determine whether to continue with the random access procedure. In addition, remaining contention among the UEs can be resolved using an existing contention resolution solution (e.g., a timing and UE-ID based resolution).

[0019] FIG. 1 illustrates an example of random access procedures between multiple user equipments (UEs) and a base station 130. For example, a first UE (UE-A) 120 can attempt to perform a random access procedure with the base station 130, and a second UE (UE-B) 110 can attempt to perform a random access procedure with the base station 130. The first UE (UE-A) 120 can include a wearable first UE (wUE-A) and the second UE (UE-B) 110 can include a wearable second UE (wUE-B). The base station 130 can include a network UE. In Step 1, the first UE (UE-A) 120 can select a temporary identifier (ID) based on a predefined technique and parameters. The temporary ID can be referred to as a temporary UE-A ID. The first UE (UE-A) 120 can transmit a first random access channel (RACH) message (or a first 'message Γ) to the base station 130, and the temporary ID associated with the first UE (UE-A) 120 can be embedded in the first RACH message.

[0020] In one example, the second UE (UE-B) 110 can select the same temporary ID as compared to the first UE (UE-A) 120. The temporary ID can be referred to as a temporary UE-B ID, and this temporary ID can be the same as the temporary UE-A ID selected by the first UE (UE-A) 120. The second UE (UE-B) 110 can transmit a second RACH message (or a second 'message Γ) to the base station 130, and the second RACH message can be transmitted on a same random access channel as compared to the first RACH message transmitted by the first UE (UE-A) 120. In other words, the first RACH message transmitted by the first UE (UE-A) 120 can collide with the second RACH message transmitted by the second UE (UE-B) 110.

[0021] In one example, the base station 130 can receive both the first RACH message and the second RACH message. The first RACH message and the second RACH message can be merged at the base station 130 to create an aggregated signal. The base station 130 may be unable to distinguish the first RACH message from the first UE (UE-A) 120 and the second RACH message from the second UE (UE-B) 110. The aggregated signal (y _fc ) at the base station 130 can be represented as follows:

n _fc where y wherein h _A represents a channel vector between the first UE and the

base station, h _B represents a channel vector between the second UE and the base station, P _U ,A represents an uplink transmit power of the first UE, p _{u B} represents an uplink transmit power of the second UE, s _k represents a transmitted symbol at subcarrier index k, n _fc represents a noise vector at subcarrier index k, and N _t represents a number of antenna elements. A channel vector size can be equal to the number of antenna elements (N _t ) (or a number of radio frequency (RF) chains) at the base station 130. In addition,

The uplink transmit power and the number of antenna elements (N _t ) can be

configured by the base station 130.

[0022] In one example, in Step 2, the first UE (UE-A) 120 can receive a random access response (RAR) message from the base station 130. The RAR message can include a base station (BS) temporary ID. When multiple UEs select the same temporary ID and send a RACH message on the same random access channel (as in Step 1), the base station 130 can send the same RAR message to the multiple UEs. In other words, in this example, the base station 130 can send the same RAR message (with the same BS temporary ID) to the first UE (UE-A) 120 and the second UE (UE-B) 110.

[0023] In one example, if s _k (which represents a transmitted symbol, and can include a training signal) is known at the base station 130, the base station 130 can estimate a superimposed channel (h _A + h _B ) using linear estimators. The base station 130 can use Yk/IIYk II as a precoding vector to derive the RAR message (z _A}k ') received at the first UE (UE-A) 120, and the RAR message (z _{B k} ') received at the second UE (UE-B) 110. For example, the RAR message (z _{A k} i) received at the first UE (UE-A) 120 can be represented as follows: + wherein p _d represents a downlink

transmit power of the base station, s _k ' represents a transmitted symbol at subcarrier index k, w _k i represents a downlink noise at subcarrier index k, and represents a Hermitian

of hA . Similarly, the RAR message (z _B , _k ') received at the second UE (UE-B) 110 can be represented as follows:

s

a downlink transmit power of the base station, represents a transmitted symbol, w _k '

represents a downlink noise at subcarrier index represents a Hermitian of h _B .

[0024] In one example, as the number of antenna elements (N _t ) increases, the following equations can be derived:

Here, σ can represent a standard deviation of the noise n _fc . As shown above, when number of antenna elements (N _t ) increases towards infinity, and h _B can become orthogonal.

[0025] Moreover, for finite N _t , the RAR message (z _Aik ') received at the first UE (UE-A) 120 can be represented as follows:

[0026] Furthermore, the following can be derived:

As shown, can represent the sum of channel gains (or aggregated

channel gain) for the first UE (UE-A) 120 and the second UE (UE-B) 110 (i.e., for colliding channels). The sum of channel gains (or aggregated channel gain) can be a total channel gain for all of the channels involved in the collision. The first UE (UE-A) 120 can estimate the sum of channel gains (or aggregated channel gain) using the RAR message (z _Aik ') received at the first UE (UE-A) 120 and knowledge of its own channel gain which can also be referred to as a first UE channel gain. The first UE (UE-

A) 120 can previously obtain knowledge about its own channel gain ( during

synchronization or a discovery period. Therefore, the first UE (UE-A) 120 can determine

, which is equal to the sum of channel gains (or aggregated channel

gain). In addition,

[0027] In one configuration, the first UE (UE-A) 120 can perform a power based contention resolution in accordance with the following:

The first UE (UE-A) 120 can compare a ratio of the first UE channel gain (e.g., and the sum of channel gains (or aggregated channel gain) (e.g.,

to ^a defined threshold. The defined threshold can be previously

configured by the base station 130.

[0028] When the ratio of the first UE channel gain and the sum of channel gains (or aggregated channel gain) is greater than the defined threshold, then the first UE (UE-A) 120 can continue the random access procedure. When the ratio is greater than the defined threshold, then this indicates that the first UE's channel gain is larger than respective channel gains for other colliding channels. In this example, the first UE (UE-A) 120 can be active, and continue the random access procedure. For example, the first UE (UE-A) 120 can subsequently transmit a connection request message (message 3) to the base station 130, and then receive a contention resolution message (message 4) from the base station 130.

[0029] In one example, when the ratio of the first UE channel gain and the sum of channel gains (or aggregated channel gain) is greater than the defined threshold, the first UE (UE-A) 120 can send signaling to the base station 130 to indicate that the ratio is greater than the defined threshold.

[0030] When the ratio of the first UE channel gain and the sum of channel gains (or aggregated channel gain) is less than the defined threshold, then the first UE (UE-A) 120 can stop the random access procedure and initiate a subsequent random access procedure in a subsequent available RACH period. When the ratio is less than the defined threshold, then this indicates that the first UE's channel gain is less than respective channel gains for other colliding channels. In this example, the first UE (UE-A) 120 can become inactive, and wait until the subsequent available RACH period to reinitiate the random access procedure. By stopping the random access procedure and waiting until the subsequent available RACH period, the first UE (UE-A) 120 can reduce its energy consumption and probability of a collision during the connection request message. In other words, when the ratio is below the defined threshold, the likelihood of a subsequent collision is relatively high anyway, so it can be more efficient (e.g., from an energy consumption perspective) for the first UE (UE-A) 120 to stop the random access procedure and reinitiate the random access procedure at a later time.

[0031] Similarly, the second UE (UE-B) 110 can perform a power based contention resolution in accordance with the following

The second UE (UE-B) 110 can compare a ratio of the second UE channel gain (e.g., PU,A llhfi || ² ) and the sum of channel gains (or aggregated channel gain) (e.g.,

PU,A + PU,B ||hfi II ² ) to the defined threshold. When the ratio of the second UE channel gain and the sum of channel gains (or aggregated channel gain) is greater than the defined threshold, then the second UE (UE-B) 110 can continue the random access procedure. When the ratio of the second UE channel gain and the sum of channel gains (or aggregated channel gain) is less than the defined threshold, then the second UE (UE- B) 110 can stop the random access procedure and initiate a subsequent random access procedure in a subsequent available RACH period.

[0032] In one example, when the number of antenna elements (N _T ) is relatively large, the channel gain can only change minimally over time due to channel hardening. Therefore, a channel gain estimated during a previous radio resource control (RRC) connection can be used.

[0033] In another configuration, the first UE (UE-A) 120 can perform a power based contention resolution in accordance with the following: can represent the

sum of channel gains (or aggregated channel gain) for colliding channels, and ||yfc || ² can be provided to the first UE (UE-A) 120 by the base station 130. Therefore, the first UE knowledge of the first can be

approximately equal to can compare

to the defined threshold. When the ratio is greater than the

defined threshold, then the first UE (UE-A) 120 can continue the random access procedure. When the ratio is less than the defined threshold, then the first UE (UE-A) 120 can stop the random access procedure and initiate a subsequent random access procedure in a subsequent available RACH period.

[0034] Similarly, the second UE (UE-B) 110 can perform a power based contention resolution in accordance with the following: threshold. Here, can represent the

sum of channel gains (or aggregated channel gain) for colliding channels, and ||y _fc || ² can be provided to the second UE (UE-B) 110 by the base station 130. Therefore, the second

UE (UE-B) 110 can calculate knowledge of the second UE

approximately equal to

to the defined threshold. When the ratio is greater than the

defined threshold, then the second UE (UE-B) 110 can continue the random access procedure. When the ratio is less than the defined threshold, then the second UE (UE-B) 110 can stop the random access procedure and initiate a subsequent random access procedure in a subsequent available RACH period.

[0035] In one configuration, the first UE (UE-A) 120 and the second UE (UE-B) 110 can both be attempting to perform the random access procedure at the same time. Both the first UE (UE-A) 120 and the second UE (UE-B) 110 can perform the power based contention resolution (as described above) after receipt of message 2 (i.e., the RAR message), and as a result, one UE can become active and continue with the random access procedure, while the other UE can become inactive. Therefore, one of the first UE (UE- A) 120 and the second UE (UE-B) 110 can subsequently perform messages 3 and 4 in the random access procedure.

[0036] In one example, the base station 130 can send the RAR message (message 2) to all the UEs that send RACH messages (message 1) on the same frequency -time channel using the same "temp UE ID". After receiving the RAR message (message 2), each UE can perform the power based contention resolution (as described above) in a distributed manner.

[0037] In Step 3, a UE (e.g., the first UE (UE-A) 120 or the second UE (UE-B) 110) can send a connection request message to the base station 130 (message 3). The connection request message can include a timing advance and random UE ID (e.g., a medium access control (MAC) ID). During a timing or UE ID based contention resolution, the base station 130 can attempt to decode the connection request message that includes the random UE ID. If the base station 130 fails to decode the connection request message, the base station 130 can additionally broadcast a message to the UE using the channel vectors, and the message can include information regarding when to initiate random access. Alternatively, the base station 130 can broadcast the message to a group identity (ID). The group IP can be used for group paging, such that UEs having the same group ID can start random access on specific random access channels. If the base station 130 successfully decodes the connection request message, the base station 130 can additionally broadcast a message to the UE (which is unselected) using the channel vectors, and the message can include information regarding when to initiate random access. Alternatively, the base station 130 can broadcast the message to the group ID. In addition, when constructing a precoding vector for the message, the channel vector obtained in Step 1 can be projected to an orthogonal subspace of the channel vector obtained in Step 2.

[0038] In Step 4, the UE (e.g., the first UE (UE-A) 120 or the second UE (UE-B) 110) can receive a random access response from the base station 130. When the base station 130 determines that there is no temporary ID contention (e.g., the base station 130 determines that only one UE is sending a random UE ID in Step 3), the base station 130 can send an acknowledgement (ACK) to the UE indicating that the contention resolution was successful. Otherwise, the base station 130 can send a negative acknowledgement (NACK) to the UE.

[0039] In one configuration, the power based contention resolution described above is available when the network uses a precoding or beamforming approach. The network can determine to use the precoding or beamforming approach during the random access procedure, and the network can indicate its intent to use the precoding or beamforming approach to the UE. As a result, this indication can prepare the UE to perform the power based contention resolution.

[0040] In one example, the random access procedure described above can be a 2-step random access procedure or a 4-step random access procedure. In the 2-step random access procedure, message 1 and message 2 can be performed, and then based on the power based contention resolution, the UE can become inactive until a next available RACH period. In the 2-step random access procedure, message 1 and message 2 can be performed, and then based on the power based contention resolution, the UE can become active and perform messages 3 and 4.

[0041] In one example, the base station can have additional knowledge about estimated channel parameters for the active UE and inactive UEs. For example, after a RACH message transmission (i.e., message 1), the base station can estimate a mixed channel gain (or total channel gain) for all of the colliding UEs. After the UEs perform power based contention resolution, the base station can detect an active UE. The base station can estimate a channel gain (or channel vector) for the active UE during Step 3 of the random access procedure. The base station can subtract the channel gain (or channel vector) for the active UE from the mixed channel gain (or total channel gain) for all of the colliding UEs. As a result, the base station can determine channel information (or channel parameters) for the inactive UEs. Based on the channel information for the inactive UEs, the base station can determine various types of information that can be signaled to the inactive UEs. Examples of such information can include a next available RACH resource (time) or preferred channel information for the next RACH procedure. Such information can be utilized by the inactive UEs during a subsequent random access procedure.

[0042] FIGS. 2-6 illustrate examples of performances for power based contention resolution techniques. For performance evaluation, two UE can be considered to perform random access on a same channel. The variable p can be used to control average channel gains of the UE, e.g., During simulation, the following parameters were set: Monte Carlo runs.

[0043] In FIGS. 2-6, the y-axis can indicate a probability of resolving a contention, and the x-axis can indicate an average channel gain ratio (p) between a first UE and a second UE, and the average channel gain ratio (p) can be represented in decibels (dB). [0044] As shown in FIG. 2, when both UEs are active (i.e., both the first UE and the second UE proceed to Step 3 for message 3), the probability of resolving the contention can decrease as the average channel gain ratio (p) increases. When both UEs are active, the UEs fail to resolve contention at Step 2, but can resolve the contention at Step 4. When a single UE is active (i.e., a single UE proceeds to Step 3 for message 3), the probability of resolving the contention can increase as the average channel gain ratio (p) increases. When the single UE is active, the UEs were successful in resolving the contention at Step 2. When both UEs are inactive (i.e., neither the first UE nor the second UE proceed to Step 3 for message 3), the probability of resolving the contention can be approximately zero. When both UEs are inactive, the UEs failed to resolve the contention at Step 2, and can try random access again at a later time. In FIG. 2, the number of antenna elements (N _t ) can be equal to 4 and a defined threshold can be set to -5.4 dB.

[0045] As shown in FIG. 3, when both UEs are active, the probability of resolving the contention can decrease as the average channel gain ratio (p) increases. When a single UE is active, the probability of resolving the contention can increase as the average channel gain ratio (p) increases. When both UEs are inactive, the probability of resolving the contention can be approximately zero. In FIG. 3, the number of antenna elements (N _t ) can be equal to 16 and a defined threshold can be set to -4.4 dB.

[0046] As shown in FIG. 4, when both UEs are active, the probability of resolving the contention can decrease as the average channel gain ratio (p) increases. When a single UE is active, the probability of resolving the contention can increase as the average channel gain ratio (p) increases. When both UEs are inactive, the probability of resolving the contention can be approximately zero. In FIG. 4, the number of antenna elements (N _t ) can be equal to 128 and a defined threshold can be set to -3.5 dB.

[0047] As shown in FIG. 5, when both UEs are active and a defined threshold is set to - 4.4 dB, the probability of resolving the contention can decrease as the average channel gain ratio (p) increases. When a single UE is active and a defined threshold is set to -4.4 dB, the probability of resolving the contention can increase as the average channel gain ratio (p) increases. When both UEs are inactive and a defined threshold is set to -4.4 dB, the probability of resolving the contention can be approximately zero. When both UEs are active and a defined threshold is set to -3.4 dB, the probability of resolving the contention can decrease as the average channel gain ratio (p) increases. When a single UE is active and a defined threshold is set to -3.4 dB, the probability of resolving the contention can increase as the average channel gain ratio (p) increases. When both UEs are inactive and a defined threshold is set to -3.4 dB, the probability of resolving the contention can become zero as the average channel gain ratio (p) increases. In FIG. 5, the number of antenna elements (N _t ) can be equal to 16.

[0048] As shown in FIG. 6, when both UEs are active and a defined threshold is set to - 3.5 dB, the probability of resolving the contention can decrease as the average channel gain ratio (p) increases. When a single UE is active and a defined threshold is set to -3.5 dB, the probability of resolving the contention can increase as the average channel gain ratio (p) increases. When both UEs are inactive and a defined threshold is set to -3.5 dB, the probability of resolving the contention can be approximately zero. When both UEs are active and a defined threshold is set to -3.1 dB, the probability of resolving the contention can decrease as the average channel gain ratio (p) increases. When a single UE is active and a defined threshold is set to -3.1 dB, the probability of resolving the contention can increase as the average channel gain ratio (p) increases. When both UEs are inactive and a defined threshold is set to -3.1 dB, the probability of resolving the contention can become zero as the average channel gain ratio (p) increases. In FIG. 6, the number of antenna elements (N _t ) can be equal to 128.

[0049] As shown in FIGS. 2-6, the probability of resolving the contention at Step 2 can increase as the number of antenna elements (N _t ) increases. In addition, the performance of power based contention resolution can depend on the defined threshold. For example, when the defined threshold is reduced, the probabilities of resolving the contention when a single UE is active and when both UEs are inactive (and vice versa) can be reduced. Therefore, the detection threshold can be designed in consideration of the number of antenna elements (N _t ) and a target performance for power based contention resolution.

[0050] FIG. 7 illustrates an exemplary system architecture for supporting wearable devices. The system architecture can include a first wearable user equipment (wUE) 702, a second wUE 706, a third wUE 710 and a network UE (nUE) 704. The first wUE 702, the second wUE 706, the third wUE 710 and the nUE 704 can form a personal area network (PAN). The nUE 704 can have a standalone network connection, whereas the first wUE 702, the second wUE 706, the third wUE 710 may not have a standalone network connection. The first wUE 702 can communicate with the nUE 704 via an Xu-a interface, and the second wUE 706 can communicate with the nUE 704 via an Xu-a interface. In other words, the Xu-a interface can be an intra-PAN air interface between the nUE and wUEs. The second wUE 706 and the third wUE 710 can communicate via an Xu-a interface. In other words, the Xu-b interface can be an intra-PAN air interface between wUEs. In addition, the system architecture can include an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) 708 and an Evolved Packet Core (EPC) 712. The E-UTRAN 708 can communicate with the first, second and third wUEs 702, 706, 710 using an Uu-w interface, and the E-UTRAN 708 can communicate with the nUE 704 over an Uu-p interface. The E-UTRAN 708 can communicate with the EPC 712 via an SI interface.

[0051] Another example provides functionality 800 of a first user equipment (UE) operable to perform power based contention resolution between the first UE and a second UE during a random access procedure, as shown in FIG. 8. The first UE can comprise one or more processors configured to: signal, at the first UE, a first random access channel (RACH) message for transmission to a base station, as in block 810. The first UE can comprise one or more processors configured to: decode, at the first UE, a random access response (RAR) message received from the base station, as in block 820. The first UE can comprise one or more processors configured to: determine, at the first UE, an aggregated channel gain for the first UE and the second UE using power based contention resolution information included in the RAR message and knowledge of a channel gain for the first UE, as in block 830. The first UE can comprise one or more processors configured to: compare, at the first UE, a ratio of the channel gain for the first UE and the aggregated channel gain relative to a defined threshold, as in block 840. The first UE can comprise one or more processors configured to: determine, at the first UE, when to continue the random access procedure for the first UE based on a comparison of the ratio to the defined threshold to achieve power based contention resolution of the random access procedure at the first UE, as in block 850.

[0052] Another example provides functionality 900 of a base station operable to perform a random access procedure for a first user equipment (UE) and a second UE, as shown in FIG. 9. The base station can comprise one or more processors configured to: decode, at the base station, an aggregated signal that is received from the first UE and the second UE during respective random access procedures with the first UE and the second UE, wherein the aggregated signal includes a first random access channel (RACH) message from the first UE that collides with a second RACH message from the second UE, as in block 910. The base station can comprise one or more processors configured to: signal, at the base station, a random access response (RAR) message for transmission to the first UE, wherein a random access procedure between the base station and the first UE is stopped or continued by the first UE depending on power based contention resolution information included in the RAR message, as in block 920. The base station can comprise one or more processors configured to: signal, at the base station, the RAR message for transmission to the first UE, wherein a random access procedure between the base station and the second UE is stopped or continued by the second UE depending on power based contention resolution information included in the RAR message, as in block 930.

[0053] Another example provides at least one machine readable storage medium having instructions 1000 embodied thereon for performing power based contention resolution between a first user equipment (UE) and a second UE during a random access procedure, as shown in FIG. 10. The instructions can be executed on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The instructions when executed perform: signaling, at the first UE, a first random access channel (RACH) message for transmission to a base station, as in block 1010. The instructions when executed perform: decoding, at the first UE, a random access response (RAR) message received from the base station, as in block 1020. The instructions when executed perform: determining, at the first UE, an aggregated channel gain for the first UE and the second UE using power based contention resolution information included in the RAR message and knowledge of a channel gain for the first UE, as in block 1030. The instructions when executed perform: comparing, at the first UE, a ratio of the channel gain for the first UE and the aggregated channel gain for the first UE and the second UE to a defined threshold, as in block 1040. The instructions when executed perform: determining, at the first UE, when to continue the random access procedure for the first UE based on a comparison of the ratio to the defined threshold to achieve power based contention resolution of the random access procedure at the first UE, as in block 1050. [0054] FIG. 11 provides an example illustration of a user equipment (UE) device 1100 and a node 1120. The UE device 1100 can include a wireless device, a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet, a handset, or other type of wireless device. The UE device 1100 can include one or more antennas configured to communicate with the node 1120 or transmission station, such as a base station (BS), an evolved Node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radio equipment (R E), a relay station (RS), a radio equipment (RE), a remote radio unit (RRU), a central processing module (CPM), or other type of wireless wide area network (WWAN) access point. The node 1120 can include one or more processors 1122, memory 1124 and a transceiver 1126. The UE device 1100 can be configured to communicate using at least one wireless communication standard including 3 GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and WiFi. The UE device 1100 can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards. The UE device 1100 can communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and/or a WWAN.

[0055] In some embodiments, the UE device 1100 may include application circuitry 1102, baseband circuitry 1104, Radio Frequency (RF) circuitry 1106, front-end module (FEM) circuitry 1108 and one or more antennas 1110, coupled together at least as shown. In addition, the node 1120 may include, similar to that described for the UE device 1100, application circuitry, baseband circuitry, Radio Frequency (RF) circuitry, front-end module (FEM) circuitry and one or more antennas

[0056] The application circuitry 1102 may include one or more application processors. For example, the application circuitry 1102 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with and/or may include a storage medium, and may be configured to execute instructions stored in the storage medium to enable various applications and/or operating systems to run on the system.

[0057] The baseband circuitry 1104 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 1104 may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of the RF circuitry 1106 and to generate baseband signals for a transmit signal path of the RF circuitry 1106. Baseband processing circuity 1104 may interface with the application circuitry 1102 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 1106. For example, in some embodiments, the baseband circuitry 1104 may include a second generation (2G) baseband processor 1104a, third generation (3G) baseband processor 1104b, fourth generation (4G) baseband processor 1104c, and/or other baseband processor(s) 1104d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 1104 (e.g., one or more of baseband processors 1104a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 1106. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 1104 may include Fast-Fourier Transform (FFT), precoding, and/or constellation

mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 1104 may include convolution, tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoder functionality.

Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

[0058] In some embodiments, the baseband circuitry 1104 may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (EUTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU) 1104e of the baseband circuitry 1104 may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processor(s) (DSP) 1104f. The audio DSP(s) 1104f may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 1104 and the application circuitry 1102 may be implemented together such as, for example, on a system on a chip (SOC).

[0059] In some embodiments, the baseband circuitry 1104 may provide for

communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 1104 may support communication with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 1104 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

[0060] The RF circuitry 1106 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 1106 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 1106 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 1108 and provide baseband signals to the baseband circuitry 1104. RF circuitry 1106 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 1104 and provide RF output signals to the FEM circuitry 1108 for transmission.

[0061] In some embodiments, the RF circuitry 1106 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 1106 may include mixer circuitry 1106a, amplifier circuitry 1106b and filter circuitry 1106c. The transmit signal path of the RF circuitry 1106 may include filter circuitry 1106c and mixer circuitry 1106a. RF circuitry 1106 may also include synthesizer circuitry 1106d for synthesizing a frequency for use by the mixer circuitry 1106a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 1106a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 1108 based on the synthesized frequency provided by synthesizer circuitry 1106d. The amplifier circuitry 1106b may be configured to amplify the down-converted signals and the filter circuitry 1106c may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 1104 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a necessity. In some embodiments, mixer circuitry 1106a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[0062] In some embodiments, the mixer circuitry 1106a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 1106d to generate RF output signals for the FEM circuitry 1108. The baseband signals may be provided by the baseband circuitry 1104 and may be filtered by filter circuitry 1106c. The filter circuitry 1106c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.

[0063] In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a of the transmit signal path may include two or more mixers and may be arranged for quadrature down-conversion and/or up-conversion respectively. In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a may be arranged for direct down-conversion and/or direct up-conversion, respectively. In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a of the transmit signal path may be configured for super-heterodyne operation.

[0064] In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these altemate embodiments, the RF circuitry 1106 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 1104 may include a digital baseband interface to communicate with the RF circuitry 1106.

[0065] In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

[0066] In some embodiments, the synthesizer circuitry 1106d may be a fractional-N synthesizer or a fractional N/N+l synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 1106d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[0067] The synthesizer circuitry 1106d may be configured to synthesize an output frequency for use by the mixer circuitry 1106a of the RF circuitry 1106 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 1106d may be a fractional N/N+l synthesizer.

[0068] In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a necessity. Divider control input may be provided by either the baseband circuitry 1104 or the applications processor 1102 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 1102.

[0069] Synthesizer circuitry 1106d of the RF circuitry 1106 may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+l (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0070] In some embodiments, synthesizer circuitry 1106d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some embodiments, the RF circuitry 1106 may include an IQ/polar converter.

[0071] FEM circuitry 1108 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 1110, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 1106 for further processing. FEM circuitry 1108 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 1106 for transmission by one or more of the one or more antennas 1110.

[0072] In some embodiments, the FEM circuitry 1108 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include a low-noise amplifier (LNA) to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 1106). The transmit signal path of the FEM circuitry 1108 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 1106), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 1110.

[0073] FIG. 12 provides an example illustration of the wireless device, such as a user equipment (UE), a mobile station (MS), a mobile wireless device, a mobile

communication device, a tablet, a handset, or other type of wireless device. The wireless device can include one or more antennas configured to communicate with a node, macro node, low power node (LPN), or, transmission station, such as a base station (BS), an evolved Node B (eNB), a baseband processing unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a relay station (RS), a radio equipment (RE), or other type of wireless wide area network (WWAN) access point. The wireless device can be configured to communicate using at least one wireless communication standard such as, but not limited to, 3 GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and WiFi. The wireless device can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards. The wireless device can communicate in a wireless local area network

(WLAN), a wireless personal area network (WPAN), and/or a WWAN. The wireless device can also comprise a wireless modem. The wireless modem can comprise, for example, a wireless radio transceiver and baseband circuitry (e.g., a baseband processor). The wireless modem can, in one example, modulate signals that the wireless device transmits via the one or more antennas and demodulate signals that the wireless device receives via the one or more antennas.

[0074] FIG. 12 also provides an illustration of a microphone and one or more speakers that can be used for audio input and output from the wireless device. The display screen can be a liquid crystal display (LCD) screen, or other type of display screen such as an organic light emitting diode (OLED) display. The display screen can be configured as a touch screen. The touch screen can use capacitive, resistive, or another type of touch screen technology. An application processor and a graphics processor can be coupled to internal memory to provide processing and display capabilities. A non-volatile memory port can also be used to provide data input/output options to a user. The non-volatile memory port can also be used to expand the memory capabilities of the wireless device. A keyboard can be integrated with the wireless device or wirelessly connected to the wireless device to provide additional user input. A virtual keyboard can also be provided using the touch screen.

Examples

[0075] The following examples pertain to specific technology embodiments and point out specific features, elements, or actions that can be used or otherwise combined in achieving such embodiments.

[0076] Example 1 includes an apparatus of a first user equipment (UE) operable to perform power based contention resolution between the first UE and a second UE during a random access procedure, the first UE comprising one or more processors configured to: signal, at the first UE, a first random access channel (RACH) message for transmission to a base station; decode, at the first UE, a random access response (RAR) message received from the base station; determine, at the first UE, an aggregated channel gain for the first UE and the second UE using power based contention resolution information included in the RAR message and knowledge of a channel gain for the first UE; compare, at the first UE, a ratio of the channel gain for the first UE and the aggregated channel gain relative to a defined threshold; and determine, at the first UE, when to continue the random access procedure for the first UE based on a comparison of the ratio to the defined threshold to achieve power based contention resolution of the random access procedure at the first UE.

[0077] Example 2 includes the apparatus of Example 1, further comprising a transceiver configured to: transmit the first RACH message to the base station; and receive the RAR message from the base station.

[0078] Example 3 includes the apparatus of any of Examples 1 to 2, further comprising memory configured to store one or more of: the power based contention resolution information, the ratio of the channel gain for the first UE and the aggregated channel gain, or the defined threshold.

[0079] Example 4 includes the apparatus of any of Examples 1 to 3, wherein the one or more processors are further configured to: determine that the ratio of the channel gain for the first UE and the aggregated channel gain is greater than the defined threshold; and determine to continue the random access procedure, wherein the random access procedure includes transmitting a connection request message from the first UE to the base station and receiving a contention resolution message at the first UE from the base station.

[0080] Example 5 includes the apparatus of any of Examples 1 to 4, wherein the one or more processors are further configured to: determine that the ratio of the channel gain for the first UE and the aggregated channel gain is less than the defined threshold; and determine to stop the random access procedure and initiate a subsequent random access procedure in a subsequent available RACH period.

[0081] Example 6 includes the apparatus of any of Examples 1 to 5, wherein the first RACH message is transmitted on a same random access channel as the second RACH message, and the first RACH message includes a same temporary identifier (ID) as the second RACH message, thereby causing the first RACH message to collide with the second RACH message.

[0082] Example 7 includes the apparatus of any of Examples 1 to 6, wherein the one or more processors are further configured to process, at the first UE, signaling for transmission to the base station, and the signaling indicates that the ratio of the channel gain for the first UE and the aggregated channel gain is greater than the defined threshold.

[0083] Example 8 includes the apparatus of any of Examples 1 to 7, wherein the first RACH message and the second RACH message are merged at the base station to create an aggregated signal, wherein the aggregated signal (y _fc ) is represented as follows: y _k = wherein represents a channel vector

between the first UE and the base station, h _B represents a channel vector between the second UE and the base station, p _{u A} represents an uplink transmit power of the first UE, PU,B represents an uplink transmit power of the second UE, s _k represents a transmitted symbol at subcarrier index k, n _fc represents a noise vector at subcarrier index k, and N _t represents a number of antenna elements.

[0084] Example 9 includes the apparatus of any of Examples 1 to 8, wherein the RAR message (z _A}k ') received at the first UE from the base station is represented as follows:

transmit power of the base station, s _k i represents a transmitted symbol at subcarrier index k, w _k i represents a downlink noise at subcarrier index represents a Hermitian

of h _A .

[0085] Example 10 includes the apparatus of any of Examples 1 to 9, wherein the one or more processors are further configured to determine the aggregated channel gain for the first UE and the second UE using the RAR message (z _{A k} i) received from the base station and knowledge of the channel gain for the first as follows:

A

deviation of the noise n _fc .

[0086] Example 11 includes the apparatus of any of Examples 1 to 10, wherein the one or more processors are further configured to perform the power based contention resolution by comparing the ratio of the channel gain for the first and the

aggregated channel gain to the defined threshold as follows:

[0087] Example 12 includes the apparatus of any of Examples 1 to 11, wherein the one or more processors are further configured to perform the power based contention resolution by comparing the ratio of the channel gain for the first and the

aggregated channel gain ) to the defined threshold as follows:

threshold, wherein the base station

informs the first UE about the aggregated channel gain (||y _fc || ² ), which enables the first UE to perform the power based contention resolution without knowledge of the channel gain for the first .

[0088] Example 13 includes an apparatus of a base station operable to perform a random access procedure for a first user equipment (UE) and a second UE, the base station comprising one or more processors configured to: decode, at the base station, an aggregated signal that is received from the first UE and the second UE during respective random access procedures with the first UE and the second UE, wherein the aggregated signal includes a first random access channel (RACH) message from the first UE that collides with a second RACH message from the second UE; signal, at the base station, a random access response (RAR) message for transmission to the first UE, wherein a random access procedure between the base station and the first UE is stopped or continued by the first UE depending on power based contention resolution information included in the RAR message; and signal, at the base station, the RAR message for transmission to the first UE, wherein a random access procedure between the base station and the second UE is stopped or continued by the second UE depending on power based contention resolution information included in the RAR message.

[0089] Example 14 includes the apparatus of Example 13, wherein the first RACH message is transmitted on a same random access channel as the second RACH message, and the first RACH message includes a same temporary identifier (ID) as the second RACH message, thereby causing the first RACH message to collide with the second RACH message.

[0090] Example 15 includes the apparatus of any of Examples 13 to 14, wherein the aggregated signal (y _fc ) is represented as follows

wherein h _A represents a channel vector between the first UE and the base station, h _B represents a channel vector between the second UE and the base station, P _U ,A represents an uplink transmit power of the first UE, p _{u B} represents an uplink transmit power of the second UE, s _k represents a transmitted symbol at subcarrier index k, n _fc represents a noise vector at subcarrier index k, and N _T represents a number of antenna elements.

[0091] Example 16 includes the apparatus of any of Examples 13 to 15, wherein the RAR message (z _A}k ') signaled from the base station to the first UE is represented as follows: k

transmit power of the base station, s _k i represents a transmitted symbol at subcarrier index k, w _k i represents a downlink noise at subcarrier index represents a Hermitian

of h _A .

[0092] Example 17 includes at least one machine readable storage medium having instructions embodied thereon for performing power based contention resolution between a first user equipment (UE) and a second UE during a random access procedure, the instructions when executed by one or more processors at the first UE perform the following: signaling, at the first UE, a first random access channel (RACH) message for transmission to a base station; decoding, at the first UE, a random access response (RAR) message received from the base station; determining, at the first UE, an aggregated channel gain for the first UE and the second UE using power based contention resolution information included in the RAR message and knowledge of a channel gain for the first UE; comparing, at the first UE, a ratio of the channel gain for the first UE and the aggregated channel gain for the first UE and the second UE to a defined threshold; and determining, at the first UE, when to continue the random access procedure for the first UE based on a comparison of the ratio to the defined threshold to achieve power based contention resolution of the random access procedure at the first UE. [0093] Example 18 includes the at least one machine readable storage medium of Example 17, further comprising instructions when executed perform the following:

determining that the ratio of the channel gain for the first UE and the aggregated channel gain is greater than the defined threshold; and determining to continue the random access procedure, wherein the random access procedure includes transmitting a connection request message from the first UE to the base station and receiving a contention resolution message at the first UE from the base station.

[0094] Example 19 includes the at least one machine readable storage medium of any of Examples 17 to 18, further comprising instructions when executed perform the following: determining that the ratio of the channel gain for the first UE and the aggregated channel gain is less than the defined threshold; and determining to stop the random access procedure and initiate a subsequent random access procedure in a subsequent available RACH period.

[0095] Example 20 includes the at least one machine readable storage medium of any of Examples 17 to 19, wherein the first RACH message is transmitted on a same random access channel as the second RACH message, and the first RACH message includes a same temporary identifier (ID) as the second RACH message, thereby causing the first RACH message to collide with the second RACH message.

[0096] Example 21 includes the at least one machine readable storage medium of any of Examples 17 to 20, wherein the first RACH message and the second RACH message are merged at the base station to create an aggregated signal, wherein the aggregated signal (y _fc ) is represented as follows:

wherein h _A represents a channel vector between the first UE and the base station, h _B represents a channel vector between the second UE and the base station, p _{u A} represents an uplink transmit power of the first UE, p _{u B} represents an uplink transmit power of the second UE, s _k represents a transmitted symbol at subcarrier index k, n _fc represents a noise vector at subcarrier index k, and N _t represents a number of antenna elements

[0097] Example 22 includes the at least one machine readable storage medium of any of Examples 17 to 21, wherein the RAR messa e (z _Aik ') received at the base station is represented as follows:

wherein p _d represents a downlink transmit power of the base station, s _k i represents a transmitted symbol at subcarrier index k, w _k i represents a downlink noise at subcarrier index k, and

represents a Hermitian of h _A .

[0098] Example 23 includes the at least one machine readable storage medium of any of Examples 17 to 22, further comprising instructions when executed perform the following: determining the aggregated channel gain for the first UE and the second UE using the RAR message (z _A}k ') received from the base station and knowledge of the channel gain for the first UE

wherein σ represents a standard deviation of the noise n _fc .

[0099] Example 24 includes the at least one machine readable storage medium of any of Examples 17 to 23, further comprising instructions when executed perform the following: performing the power based contention resolution by comparing the ratio of the channel gain for the first U

to the defined threshold as follows:

[00100] Example 25 includes the at least one machine readable storage medium of any of Examples 17 to 24, further comprising instructions when executed perform the following: performing the power based contention resolution by comparing the ratio of the channel gain for the first and the aggregated channel gain

to the defined threshold as follows:

threshold, wherein the base station informs the first UE about the

aggregated channel gain (||y _fc || ² ), which enables the first UE to perform the power based contention resolution without knowledge of the channel gain for the first

[00101] Example 26 includes a first user equipment (UE) operable to perform power based contention resolution with a second UE during a random access procedure, the first UE comprising: means for signaling a first random access channel (RACH) message for transmission to a base station; means for decoding a random access response (RAR) message received from the base station; means for determining an aggregated channel gain for the first UE and the second UE using power based contention resolution information included in the RAR message and knowledge of a channel gain for the first UE; means for comparing a ratio of the channel gain for the first UE and the aggregated channel gain for the first UE and the second UE to a defined threshold; and means for determining when to continue the random access procedure for the first UE based on a comparison of the ratio to the defined threshold to achieve power based contention resolution of the random access procedure at the first UE.

[00102] Example 27 includes the first UE of Example 26, further comprising means for determining that the ratio of the channel gain for the first UE and the aggregated channel gain is greater than the defined threshold; and determining to continue the random access procedure, wherein the random access procedure includes transmitting a connection request message from the first UE to the base station and receiving a contention resolution message at the first UE from the base station.

[00103] Example 28 includes the first UE of any of Examples 26 to 27, further comprising means for determining that the ratio of the channel gain for the first UE and the aggregated channel gain is less than the defined threshold; and determining to stop the random access procedure and initiate a subsequent random access procedure in a subsequent available RACH period.

[00104] Example 29 includes the first UE of any of Examples 26 to 28, wherein the first RACH message is transmitted on a same random access channel as the second RACH message, and the first RACH message includes a same temporary identifier (ID) as the second RACH message, thereby causing the first RACH message to collide with the second RACH message.

[00105] Example 30 includes the first UE of any of Examples 26 to 29, wherein the first RACH message and the second RACH message are merged at the base station to create an aggregated signal, wherein the aggregated signal (y _fc ) is represented as follows: y _k = represents a channel vector

between the first UE and the base station, h _B represents a channel vector between the second UE and the base station, p _{u A} represents an uplink transmit power of the first UE, Pu.B represents an uplink transmit power of the second UE, s _k represents a transmitted symbol at subcarrier index k, n _fc represents a noise vector at subcarrier index k, and N _t represents a number of antenna elements

[00106] Example 31 includes the first UE of any of Examples 26 to 30, wherein the RAR message (z _Aik ') received at the base station is re resented as follows:

represents a downlink transmit power of the

base station, s _k ' represents a transmitted symbol at subcarrier index k, w _k i represents a downlink noise at subcarrier index k, and

[00107] Example 32 includes the first UE of any of Examples 26 to 31, further comprising means for determining the aggregated channel gain for the first UE and the second UE using the RAR message (z _A}k ') received from the base station and knowledge of the wherein σ repres ents a standard

deviation of the noise n _fc .

[00108] Example 33 includes the first UE of any of Examples 26 to 32, further comprising means for performing the power based contention resolution by comparing the ratio of the channel gain for the first ) and the aggregated channel gain

to the defined threshold as follows:

threshold.

[00109] Example 34 includes the first UE of any of Examples 26 to 33, further means for performing the power based contention resolution by comparing the ratio of the channel gain for the first and the aggregated channel gain

to the defined threshold as follows:

threshold, wherein the base station informs the first UE about the

aggregated channel gain (||y _fc | \|2 ² ), which enables the first UE to perform the power based contention resolution without knowledge of the channel gain for the first UE (\\h _A H ² ).

[00110] Various techniques, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, compact disc-read-only memory (CD-ROMs), hard drives, non-transitory computer readable storage medium, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the various techniques. In the case of program code execution on programmable computers, the computing device may include a processor, a storage medium readable by the processor (including volatile and non- volatile memory and/or storage elements), at least one input device, and at least one output device. The volatile and non-volatile memory and/or storage elements may be a random-access memory (RAM), erasable programmable read only memory (EPROM), flash drive, optical drive, magnetic hard drive, solid state drive, or other medium for storing electronic data. The node and wireless device may also include a transceiver module (i.e., transceiver), a counter module (i.e., counter), a processing module (i.e., processor), and/or a clock module (i.e., clock) or timer module (i.e., timer). In one example, selected components of the transceiver module can be located in a cloud radio access network (C-RAN). One or more programs that may implement or utilize the various techniques described herein may use an application programming interface (API), reusable controls, and the like. Such programs may be implemented in a high level procedural or object oriented programming language to communicate with a computer system. However, the program(s) may be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language, and combined with hardware implementations.

[00111] As used herein, the term "circuitry" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware. [00112] It should be understood that many of the functional units described in this specification have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very-large-scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.

[00113] Modules may also be implemented in software for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module may not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.

[00114] Indeed, a module of executable code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. The modules may be passive or active, including agents operable to perform desired functions.

[00115] Reference throughout this specification to "an example" or "exemplary" means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment of the present technology. Thus, appearances of the phrases "in an example" or the word "exemplary" in various places throughout this specification are not necessarily all referring to the same embodiment.

[00116] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present technology may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as defacto equivalents of one another, but are to be considered as separate and autonomous representations of the present technology.

[00117] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of layouts, distances, network examples, etc., to provide a thorough understanding of embodiments of the technology. One skilled in the relevant art will recognize, however, that the technology can be practiced without one or more of the specific details, or with other methods, components, layouts, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the technology.

[00118] While the forgoing examples are illustrative of the principles of the present technology in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the technology. Accordingly, it is not intended that the technology be limited, except as by the claims set forth below.