ANTENNA SELECTION DEVICES, METHODS, & SYSTEMS

Abstract

A method, an apparatus, and a computer program product for wireless communication are provided in connection with improving antenna selection for a UE as part of an access procedure. In an example, a UE with two or more antennas is equipped to obtain receive chain measurements for the two or more antennas associated with the UE when an access procedure is initiated, select an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure, and perform the access procedure using the selected antenna. In another example, the UE is equipped to determine that an Access procedure is to be initiated, select an antenna from the two or more antennas based on a selection algorithm, and perform the Access procedure based using the selected antenna. Other aspects, embodiments, and features are also claimed and described.

Description

TECHNICAL FIELD

The present disclosure relates generally to communication systems, and more particularly, to improving antenna selection for a user equipment (UE) during an access procedure.

BACKGROUND

Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the UMTS, a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division—Code Division Multiple Access (TD-CDMA), and Time Division—Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.

As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

Generally, when a user attempts to originate a call or receives call, one antenna of two or more antennas of the UE may have some blockage (e.g., due to hand restriction, etc.), based on a device specific architecture. When such a blockage occurs, it is possible that a second antenna of the UE has comparatively low blockage and hence routing an access procedure (e.g., access channel preambles/messages, etc.) through the second antenna may provide a comparatively better/faster chance to reach a network entity (e.g., NodeB, eNodeB, etc.).

BRIEF SUMMARY OF SOME SAMPLE EMBODIMENTS

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

In accordance with one or more aspects and corresponding disclosure thereof, various aspects are described in connection with improving antenna selection for a UE as part of an access procedure. In an example, a UE with two or more antennas is equipped to obtain receive chain measurements for the two or more antennas associated with the UE when an access procedure is initiated, select an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure, and perform the access procedure using the selected antenna. In another example, the UE is equipped to determine that an Access procedure is to be initiated, select an antenna from the two or more antennas based on a selection algorithm, and perform the Access procedure based using the selected antenna.

According to related aspects, a method for improving antenna selection for a UE as part of an access procedure is provided. The method can include obtaining, by a UE, receive chain measurements for two or more antennas associated with the UE when an access procedure is initiated. Further, the method can include selecting an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure. Moreover, the method may include performing the access procedure using the selected antenna.

Another aspect relates to a communications apparatus with improved antenna selection as part of an access procedure. The communications apparatus can include means for obtaining, by a UE, receive chain measurements for two or more antennas associated with the UE when an access procedure is initiated. Further, the communications apparatus can include means for selecting an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure. Moreover, the communications apparatus can include means for performing the access procedure using the selected antenna.

Another aspect relates to a communications apparatus. The apparatus can include a processing system configured to obtain, by a UE, receive chain measurements for two or more antennas associated with the UE when an access procedure is initiated. Further, the processing system may be configured to select an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure. Moreover, the processing system may further be configured to perform the access procedure using the selected antenna.

Still another aspect relates to a computer program product, which can have a computer-readable medium including code for obtaining, by a UE, receive chain measurements for two or more antennas associated with the UE when an access procedure is initiated. Further, the computer-readable medium can include code for selecting an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure. Moreover, the computer-readable medium can include code for performing the access procedure using the selected antenna.

According to related aspects, a method for improving antenna selection for a UE as part of an access procedure is provided. The method can include determining that an Access procedure is to be initiated. Further, the method can include selecting an antenna, from the two or more antennas, for transmission based on a selection algorithm. Moreover, the method may include performing the Access procedure based using the selected antenna.

Another aspect relates to a communications apparatus with improved antenna selection as part of an access procedure. The communications apparatus can include means for determining that an Access procedure is to be initiated. Further, the communications apparatus can include means for selecting an antenna, from the two or more antennas, for transmission based on a selection algorithm. Moreover, the communications apparatus can include means for performing the Access procedure based using the selected antenna.

Another aspect relates to a communications apparatus. The apparatus can include a processing system configured to determine that an Access procedure is to be initiated. Further, the processing system may be configured to select an antenna, from the two or more antennas, for transmission based on a selection algorithm. Moreover, the processing system may further be configured to perform the Access procedure based using the selected antenna.

Still another aspect relates to a computer program product, which can have a computer-readable medium including code for determining that an Access procedure is to be initiated. Further, the computer-readable medium can include code for selecting an antenna, from the two or more antennas, for transmission based on a selection algorithm. Moreover, the computer-readable medium can include code for performing the Access procedure based using the selected antenna.

Other aspects, features, and embodiments of the present invention will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary embodiments of the present invention in conjunction with the accompanying figures. While features of the present invention may be discussed relative to certain embodiments and figures below, all embodiments of the present invention can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various embodiments of the invention discussed herein. In similar fashion, while exemplary embodiments may be discussed below as device, system, or method embodiments it should be understood that such exemplary embodiments can be implemented in various devices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of an access network architecture according to some embodiments.

FIG. 2 is a diagram illustrating an example of another access network architecture according to some embodiments.

FIG. 3 is a diagram illustrating an example of a network entity and user equipment in an access network according to some embodiments.

FIG. 4 is a diagram illustrating an example of another access network architecture, according to some embodiments.

FIG. 5 is a diagram illustrating an example of an UL frame structure in LTE according to some embodiments.

FIG. 6 is a diagram illustrating events for a mobile terminated call over time according to some embodiments.

FIG. 7 is a flow chart illustrating a first example method for improving wireless device power consumption in an M2M environment according to some embodiments.

FIG. 8 is a flow chart illustrating a second example method for improving wireless device power consumption in an M2M environment according to some embodiments.

FIG. 9 is a conceptual data flow diagram illustrating the data flow between different modules/means/components according to some embodiments.

FIG. 10 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system according to some embodiments.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), and floppy disk where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

By way of example and without limitation, the aspects of the present disclosure illustrated in FIG. 1 are presented with reference to a UMTS system 100 employing a W-CDMA air interface and/or CDMA2000 air interface. A UMTS network includes three interacting domains: a Core Network (CN) 104, a UMTS Terrestrial Radio Access Network (UTRAN) 102, and User Equipment (UE) 110. In this example, the UTRAN 102 provides various wireless services including telephony, video, data, messaging, broadcasts, and/or other services. The UTRAN 102 may include a plurality of Radio Network Subsystems (RNSs) such as an RNS 107, each controlled by a respective Radio Network Controller (RNC) such as an RNC 106. Here, the UTRAN 102 may include any number of RNCs 106 and RNSs 107 in addition to the RNCs 106 and RNSs 107 illustrated herein. The RNC 106 is an apparatus responsible for, among other things, assigning, reconfiguring, and releasing radio resources within the RNS 107. The RNC 106 may be interconnected to other RNCs (not shown) in the UTRAN 102 through various types of interfaces such as a direct physical connection, a virtual network, or the like, using any suitable transport network.

Communication between a UE 110 and a Node B 108 may be considered as including a physical (PHY) layer and a medium access control (MAC) layer. Further, communication between a UE 110 and an RNC 106 by way of a respective Node B 108 may be considered as including a radio resource control (RRC) layer. In the instant specification, the PHY layer may be considered layer 1; the MAC layer may be considered layer 2; and the RRC layer may be considered layer 3. Information hereinbelow utilizes terminology introduced in the RRC Protocol Specification, 3GPP TS 25.331 v9.1.0, incorporated herein by reference.

The geographic region covered by the RNS 107 may be divided into a number of cells, with a radio transceiver apparatus serving each cell. A radio transceiver apparatus is commonly referred to as a Node B in UMTS applications, but may also be referred to by those skilled in the art as a base station (BS), a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology. For clarity, three Node Bs 108 are shown in each RNS 107; however, the RNSs 107 may include any number of wireless Node Bs. The Node Bs 108 provide wireless access points to a CN 104 for any number of mobile apparatuses. Examples of a mobile apparatus include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device. The mobile apparatus is commonly referred to as a UE in UMTS applications, but may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. For illustrative purposes, one UE 110 is shown in communication with a number of the Node Bs 108. The DL, also called the forward link, refers to the communication link from a Node B 108 to a UE 110, and the UL, also called the reverse link, refers to the communication link from a UE 110 to a Node B 108.

Further, UE 110 may be equipped with multiple antennas 111 that may enable communication using one or more radio access technologies (RATs). The multiple antennas 111 may be used for transmit diversity, range extension, etc. In an aspect, UE 110 may select an antenna from the multiple antennas 111 to use to access the network (e.g., Node B 108). In such an aspect, the UE 110 selection may be based on downlink measurements from the antennas 111. In an operational aspect, a user may attempt to originate a call (mobile originated (MO)) and/or receive call (mobile terminated (MT)). Further, one antenna the multiple antennas 111 may experience some blockage (e.g., due to hand restriction, etc.). In such an aspect, a second antenna of the UE 110 may experience relatively low blockage and hence routing the preambles/messages through the second antenna may result in an improved (e.g., more reliable and faster) chance to communicate with Node B 108.

The CN 104 interfaces with one or more access networks, such as the UTRAN 102. As shown, the CN 104 is a GSM core network. However, as those skilled in the art will recognize, the various concepts presented throughout this disclosure may be implemented in a RAN, or other suitable access network, to provide UEs with access to types of CNs other than GSM networks.

The CN 104 includes a circuit-switched (CS) domain and a packet-switched (PS) domain. Some of the circuit-switched elements are a Mobile services Switching Centre (MSC) 112, a Visitor location register (VLR), and a Gateway MSC. Packet-switched elements include a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN). Some network elements, like EIR, HLR, VLR and AuC may be shared by both of the circuit-switched and packet-switched domains. In the illustrated example, the CN 104 supports circuit-switched services with a MSC 112 and a GMSC 114. In some applications, the GMSC 114 may be referred to as a media gateway (MGW). One or more RNCs, such as the RNC 106, may be connected to the MSC 112. The MSC 112 is an apparatus that controls call setup, call routing, and UE mobility functions. The MSC 112 may also include a VLR that contains subscriber-related information for the duration that a UE is in the coverage area of the MSC 112. The GMSC 114 provides a gateway through the MSC 112 for the UE to access a circuit-switched network 116. The GMSC 114 includes a home location register (HLR) 115 containing subscriber data, such as the data reflecting the details of the services to which a particular user has subscribed. The HLR is also associated with an authentication center (AuC) that contains subscriber-specific authentication data. When a call is received for a particular UE, the GMSC 114 queries the HLR 115 to determine the UE's location and forwards the call to the particular MSC serving that location.

The CN 104 also supports packet-data services with a serving General Packet Radio Service (GPRS) support node (SGSN) 118 and a gateway GPRS support node (GGSN) 120. GPRS is designed to provide packet-data services at speeds higher than those available with standard circuit-switched data services. The GGSN 120 provides a connection for the UTRAN 102 to a packet-based network 122. The packet-based network 122 may be the Internet, a private data network, or some other suitable packet-based network. The primary function of the GGSN 120 is to provide the UEs 110 with packet-based network connectivity. Data packets may be transferred between the GGSN 120 and the UEs 110 through the SGSN 118, which performs primarily the same functions in the packet-based domain as the MSC 112 performs in the circuit-switched domain.

An air interface for UMTS may utilize a spread spectrum Direct-Sequence Code Division Multiple Access (DS-CDMA) system. The spread spectrum DS-CDMA spreads user data through multiplication by a sequence of pseudorandom bits called chips. The “wideband” W-CDMA air interface for UMTS is based on such direct sequence spread spectrum technology and additionally calls for a frequency division duplexing (FDD). FDD uses a different carrier frequency for the UL and DL between a Node B 108 and a UE 110. Another air interface for UMTS that utilizes DS-CDMA, and uses time division duplexing (TDD), is the TD-SCDMA air interface. Those skilled in the art will recognize that although various examples described herein may refer to a W-CDMA air interface, the underlying principles may be equally applicable to a TD-SCDMA air interface.

FIG. 2 is a diagram illustrating an LTE network architecture 200. The LTE network architecture 200 may be referred to as an Evolved Packet System (EPS) 200. The EPS 200 may include one or more user equipment (UE) 202, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 204, an Evolved Packet Core (EPC) 210, a Home Subscriber Server (HSS) 220, and an Operator's IP Services 222. The EPS can interconnect with other access networks, but for simplicity those entities/interfaces are not shown. As shown, the EPS provides packet-switched services, however, as those skilled in the art will readily appreciate, the various concepts presented throughout this disclosure may be extended to networks providing circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 206 and other eNBs 208. The eNB 206 provides user and control planes protocol terminations toward the UE 202. The eNB 206 may be connected to the other eNBs 208 via a backhaul (e.g., an X2 interface). The eNB 206 may also be referred to as a base station, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), or some other suitable terminology. The eNB 206 provides an access point to the EPC 210 for a UE 202. Examples of UEs 202 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device. The UE 202 may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

The eNB 206 is connected by an 51 interface to the EPC 210. The EPC 210 includes a Mobility Management Entity (MME) 212, other MMEs 214, a Serving Gateway 216, and a Packet Data Network (PDN) Gateway 218. The MME 212 is the control node that processes the signaling between the UE 202 and the EPC 210. Generally, the MME 212 provides bearer and connection management. All user IP packets are transferred through the Serving Gateway 216, which itself is connected to the PDN Gateway 218. The PDN Gateway 218 provides UE IP address allocation as well as other functions. The PDN Gateway 218 is connected to the Operator's IP Services 222. The Operator's IP Services 222 may include the Internet, the Intranet, an IP Multimedia Subsystem (IMS), and a PS Streaming Service (PSS).

Further, UE 202 may be equipped with multiple antennas 203 that may enable communication using one or more radio access technologies (RATs). The multiple antennas 203 may be used for transmit diversity, range extension, etc. In an aspect, UE 202 may select an antenna from the multiple antennas 203 to use to access the network (e.g., perform an access channel (ACH) procedure). In an aspect, the ACH procedure may be a random access channel (RACH) procedure. In such an aspect, the UE 202 selection may be based on downlink measurements from the antennas 203. In an operational aspect, a user may attempt to originate a call (MO) and/or receive call (MT). Further, one antenna the multiple antennas 203 may experience some blockage (e.g., due to hand restriction, etc.). In such an aspect, a second antenna of the UE 203 may experience relatively low blockage and hence routing the preambles/messages through the second antenna may result in an improved (e.g., more reliable and faster) chance to communicate with eNB 206.

The modulation and multiple access scheme employed by the access network 200 may vary depending on the particular telecommunications standard being deployed. In LTE applications, OFDM is used on the DL and SC-FDMA is used on the UL to support both frequency division duplexing (FDD) and time division duplexing (TDD). As those skilled in the art will readily appreciate from the detailed description to follow, the various concepts presented herein are well suited for LTE applications. However, these concepts may be readily extended to other telecommunication standards employing other modulation and multiple access techniques. By way of example, these concepts may be extended to Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. These concepts may also be extended to Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM) employing TDMA; and Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.

Spatial multiplexing is generally used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmission energy in one or more directions. This may be achieved by spatially precoding the data for transmission through multiple antennas. To achieve good coverage at the edges of the cell, a single stream beamforming transmission may be used in combination with transmit diversity.

In the detailed description that follows, various aspects of an access network will be described with reference to a MIMO system supporting OFDM on the DL. OFDM is a spread-spectrum technique that modulates data over a number of subcarriers within an OFDM symbol. The subcarriers are spaced apart at precise frequencies. The spacing provides “orthogonality” that enables a receiver to recover the data from the subcarriers. In the time domain, a guard interval (e.g., cyclic prefix) may be added to each OFDM symbol to combat inter-OFDM-symbol interference. The UL may use SC-FDMA in the form of a DFT-spread OFDM signal to compensate for high peak-to-average power ratio (PAPR).

FIG. 3 is a block diagram of a network entity 310 (e.g., NodeB, eNB, pico node, a femto node, etc.) in communication with a UE 350 in an access network. In the DL, upper layer packets from the core network are provided to a controller/processor 375. The controller/processor 375 implements the functionality of the L2 layer. In the DL, the controller/processor 375 provides header compression, ciphering, packet segmentation and reordering, multiplexing between logical and transport channels, and radio resource allocations to the UE 350 based on various priority metrics. The controller/processor 375 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the UE 350.

The transmit (TX) processor 316 implements various signal processing functions for the L1 layer (i.e., physical layer). The signal processing functions includes coding and interleaving to facilitate forward error correction (FEC) at the UE 350 and mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols are then split into parallel streams. Each stream is then mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 350. Each spatial stream is then provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX modulates an RF carrier with a respective spatial stream for transmission.

At the UE 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 356. The RX processor 356 implements various signal processing functions of the L1 layer. The RX processor 356 performs spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they may be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, is recovered and demodulated by determining the most likely signal constellation points transmitted by the network entity 310. These soft decisions may be based on channel estimates computed by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the network entity 310 on the physical channel. The data and control signals are then provided to the controller/processor 359.

The controller/processor 359 implements the L2 layer. The controller/processor can be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller/processor 359 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the core network. The upper layer packets are then provided to a data sink 362, which represents all the protocol layers above the L2 layer. Various control signals may also be provided to the data sink 362 for L3 processing. The controller/processor 359 is also responsible for error detection using an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support HARQ operations.

In the UL, a data source 367 is used to provide upper layer packets to the controller/processor 359. The data source 367 represents all protocol layers above the L2 layer. Similar to the functionality described in connection with the DL transmission by the network entity 310, the controller/processor 359 implements the L2 layer for the user plane and the control plane by providing header compression, ciphering, packet segmentation and reordering, and multiplexing between logical and transport channels based on radio resource allocations by the network entity 310. The controller/processor 359 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the network entity 310.

Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the network entity 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 are provided to different antenna 352 via separate transmitters 354TX. Each transmitter 354TX modulates an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the network entity 310 in a manner similar to that described in connection with the receiver function at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370. The RX processor 370 may implement the L1 layer.

The controller/processor 375 implements the L2 layer. The controller/processor 375 can be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the UE 350. Upper layer packets from the controller/processor 375 may be provided to the core network. The controller/processor 375 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

FIG. 4 depicts an example communication network 400 in which efficient antenna selection as part of an access procedure may be enabled, according to an aspect.

Communication network 400 may include a wireless device 402 (e.g., UE 110, UE 202, etc.), and a network entity 430 (e.g., Node B, eNB, etc.).

Wireless device 402 may include an application processing subsystem 404, access procedure module 408, and modem subsystem 414. In an aspect, application processing subsystem 404 may use data transaction module 406 to obtain data as part of a MO call initiation. In an aspect, modem subsystem 414 may receive a page message (e.g., paging indicator) form a network entity 430 as part of a MT call initiation. In an aspect, access procedure module 408 may determine that an access procedure is to be initiated based on internal reception of a message from the application processing subsystem 404 and/or the modem subsystem 414. Although depicted as a separate module in FIG. 4, access procedure module 408 may be associated with and/or coupled to application processing subsystem 404 and/or modem subsystem 414. In another aspect, access procedure module 408 may include multiple sub-portions, and a sub-portion may be more closely coupled to the modem subsystem 414. In another aspect, modem subsystem 414 may be coupled to multiple antennas 418, 420 and configured to use multiple radios 416. Although FIG. 4 depicts only two antennas 418, 420, one or ordinary skill in the art understands that the wireless device is not limited to two antennas and may have additional antennas beyond the depicted.

Access procedure module 408 may include a receive chain measurements module 410 and transmit antenna selection module 412. In an aspect, receive chain measurements module 410 may receive antenna 418, 420 receive chain measurements (422, 424) via modem subsystem 414. In an aspect, the UE measurements may include, but are not limited to a receive signal code power (RSCP) measurement, a Reference Signal Received Power (RSRP) measurement, a Received Signal Strength Indication (RSSI) measurement, an automatic gain control (AGC) measurement, etc. In an aspect, transmit antenna selection module 412 may select an antenna (e.g., 420) for transmissions 426 for at least a portion of an access procedure (e.g., access channel (ACH) procedure). Generally, an antenna 420 that has greater Rx chain measurement value 424 may also have less path loss on a downlink. As such, transmit antenna selection module 412 may select this antenna 420 for transmissions 426 as it may have a greater chance of having lower path loss on an uplink. Further description of an operational aspect, of access procedure module 408 is provided with reference to the flowchart in FIG. 7 below. In another aspect, transmit antenna selection module 412 may use a selection algorithm to select which antenna to use for transmissions. In an aspect, the selection algorithm may prompt the wireless device 402 to randomly and/or pseudo-randomly select an antenna 418, 420 for transmissions for at least a portion of the Access procedure. In another aspect, the selection algorithm may prompt the wireless device 402 to select an antenna 418, 420 based on a pre-determined antenna hopping pattern (e.g., antenna 0, then 1, then 0, then 1, etc.). In another aspect, the selection algorithm may prompt the wireless device 402 to using an antenna that was most recently previously successfully used. Further description of an operational aspect, of access procedure module 408 is provided with reference to the flowchart in FIG. 8 below.

FIG. 5 is a diagram 500 illustrating an example of an UL frame structure in LTE.

The available resource blocks for the UL may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.

A UE may be assigned resource blocks 510a, 510b in the control section to transmit control information to an eNB. The UE may also be assigned resource blocks 520a, 520b in the data section to transmit data to the eNB. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks in the control section. The UE may transmit only data or both data and control information in a physical UL shared channel (PUSCH) on the assigned resource blocks in the data section. A UL transmission may span both slots of a subframe and may hop across frequency.

A set of resource blocks may be used to perform initial system access and achieve UL synchronization in a physical random access channel (PRACH) 530. The PRACH 530 carries a random sequence and may carry a transmit preamble on an access slot boundary (e.g., ˜1 ms (4096 chips) using 1 of 16 signatures). Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. That is, the transmission of the random access preamble is restricted to certain time and frequency resources. There is no frequency hopping for the PRACH. The PRACH attempt is carried in a single subframe (1 ms) or in a sequence of few contiguous subframes and a UE can make only a single PRACH attempt per frame (10 ms).

FIG. 6 illustrating events 600 over time 602 for a mobile terminated call in an LTE based access network, according to an aspect.

As noted with reference to FIGS. 2 and 5, UTRAN 204 may communicate with UE 202 using a paging channel. Paging 606 may occurs through setting Paging Indicator (PI) symbol ON in the PICH. When UE 202 wakes up 604 in its DRX cycle, it may monitor for the PI symbol. When the PI symbol is set to ON, the UE 202 may read paging messages of PCH Tr Ch in SCCPCH physical channel 608 (which occurs Tau_—PICH (3 slots, or 7680 chips) later). Subsequently, a forward access channel (FACH) may be initiated 610 and the UE 202 may select 612 an antenna to use for the access channel procedure. In an aspect, the antenna may be selected based on receive chain measurements. In another aspect, the antenna may be selected based on a selection algorithm. Thereafter, UE 202 may initiate a RACH procedure 614 using PRACH 530 through the selected antenna to get radio access to send L3 messaging (e.g., a RRC Connection Request message) 616.

FIGS. 7 and 8 illustrate various methodologies in accordance with various aspects of the presented subject matter. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of acts or sequence steps, it is to be understood and appreciated that the claimed subject matter is not limited by the order of acts, as some acts may occur in different orders and/or concurrently with other acts from that shown and described herein. For example, those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a methodology in accordance with the claimed subject matter. Additionally, it should be further appreciated that the methodologies disclosed hereinafter and throughout this specification are capable of being stored on an article of manufacture to facilitate transporting and transferring such methodologies to computers. The term article of manufacture, as used herein, is intended to encompass a computer program accessible from any computer-readable device, carrier, or media.

FIG. 7 depicts a first example method 700 utilizes transmit (Tx) diversity on uplink for potentially more reliable radio access by a user equipment (UE) to the network from Idle mode (e.g., for a MT call, for a MO call, for Registration, etc.).

At block 702, a UE may determine that an access procedure is to be initiated. In an aspect in which a MO call is initiated, UE 902 application processing module 910 may provide a message 928 to access procedure module 908 indicating that application data 926 from application 911 is available to be communicated. In such an aspect, access procedure module 908 may determine that an access procedure is to be initiated based on reception of the message 928. In an aspect in which there is a MT call, reception module 904 may receive, using one or more antennas 906, a page 920 from a network entity 430 indicating that a MT call has been initiated. In such an aspect, access procedure module 908 may determine that an access procedure is to be initiated based on reception of the page 920. The UE may be enabled in use one or more access technologies, such as but not limited to, a 1x based access network, a evolved data optimized (EV-DO) based access network, a code division multiple access (CDMA) based network, UMTS based network, a long term evolution (LTE) based access network, etc. Where the UE is enabled using a 1x (e.g., EV-DO) based access network, an access probe transmission may indicate initiation of the access procedure. Where the UE is enabled using a CDMA based access network (e.g., WCDMA), a UMTS based network, a LTE based network, etc., transmission of an access channel preamble may indicate initiation of the access procedure. Where the UE is enabled to use a LTE based access network and a MT call is indicated from the network, a UTRAN communicates with UE through paging. In such an aspect, paging occurs through setting a Paging Indicator (PI) symbol ON in PICH channel. Further, when the UE wakes up in its DRX cycle, the UE monitors for a PI symbol. Still further, when the UE detects that the PI symbol is set to ON, the UE reads paging messages of PCH Tr Ch in SCCPCH physical channel (which occurs Tau_—PICH (3 slots, or 7680 chips) later. The UE may then initiate the RACH procedure to obtain radio access to send a RRC Connection Request message. In another aspect, when there is a MO call or Registration, UE may use substantially the same sequence of events as described for a MT call, except for replacing the ‘SCCPCH Complete’ step may be replaced with ‘Higher layer indication for physical channel setup’ and everything prior to this step may be considered redundant.

At block 704, the UE may perform receive (Rx) chain measurements for two or more antennas associated with the UE. In an aspect, reception module 904 may perform receive chain measurements 922 for the two or more antennas 906. Generally, an antenna that has greater Rx chain measurement value may also have less path loss on a downlink. As such, the antenna may also have a greater chance of having lower path loss on an uplink. In an aspect, the receive chain measurements may include, but are not limited to, a RSCP measurement, a RSRP measurement, a RSSI measurement, an AGC measurement, etc. In an aspect in which the UE has two antennas, receive chain measurements may be performed each of the antennas. In an aspect in which the UE has antennas associated with various access technologies (e.g., 1x, EV-DO, WCDMA, UMTS, LTE, etc), the UE may either determine which access technology with which to perform measurements and/or may perform measurements based on a determined a hierarchy among the various access technologies. For example, when the UE has multiple receiving circuits available, the UE may turn on all receiving circuits concurrently, and measure all antennas' performance for comparison. In another example, when the UE has a single receiving circuit, the UE may connect different antennas to that single receiving circuit in serial, and measure each antenna performance sequentially for the comparison.

At block 706, the UE may select an antenna from the two or more antennas based on the receive chain measurements. In an aspect, reception module 904 may provide the receive chain measurements 922 to access procedure module 908. Further, access procedure module 908 selection algorithm module 909 may make a selection 924 for which antenna to use for transmission. Further, the antenna selection 924 may be provided to transmission module 912. In an aspect, the UE may select the antenna with the greatest receive chain measurement value. In another aspect, the UE may select the antenna from one or more antennas with receive chain measurement values higher than a threshold level. In an aspect in which the UE is enabled to access a LTE based access network, the selection may occur once each access channel cycle. In another aspect, the selection may occur prior to the onset of each preamble in an access channel cycle.

At block 708, the UE may perform the access procedure using the selected antenna. In an aspect, transmission module 912 may perform the access procedure using the selected 924 antenna. After successful completion of the access procedure, application 911 data 926 may be transmitted, via transmission module 912, to a network entity 430.

In an optional aspect, at block 710, the UE may determine whether the access procedure was successful. The process may end when the UE determines the access procedure was successful.

By the contrast, in the optional aspect when the UE determines that the access procedure was not successful, at block 712, the UE may select an antenna for use during the at least a portion of the Access procedure based on one or more subsequent try selection criteria. In an aspect, the newly selected antenna may be based on the previously performed, or newly preformed receive chain measurements. In another aspect, the newly selected antenna may be randomly selected. In another aspect, where there are two antennas, the previously unselected antenna may be selected. In still another aspect, where there are three or more antennas, the antenna used in the previously attempt may be removed from a selection pool, and the newly selected antenna may be selected from the remaining antennas in the selection pool based on receive chain measurements.

FIG. 8 depicts a second example method 800 utilizes Tx diversity on uplink for potentially more reliable radio access by a UE to the network from Idle mode.

At block 802, a UE may determine that an access procedure is to be initiated. In an aspect in which a MO call is initiated, UE 902 application processing module 910 may provide a message 928 to access procedure module 908 indicating that application data 926 from application 911 is available to be communicated. In such an aspect, access procedure module 908 may determine that an access procedure is to be initiated based on reception of the message 928. In an aspect in which there is a MT call, reception module 904 may receive, using one or more antennas 906, a page 920 from a network entity 430 indicating that a MT call has been initiated. In such an aspect, access procedure module 908 may determine that an access procedure is to be initiated based on reception of the page 920.

At block 804, the UE may select an antenna from two or more antennas based on a selection algorithm. In an aspect, access procedure module 908 selection algorithm module 909 may prompt 924 the UE 902 to select an antenna from two or more antennas based on a selection algorithm. In an aspect, the selection algorithm module 909 may prompt 924 the UE 902 to randomly and/or pseudo-randomly select an antenna for use during at least a portion of the Access procedure. In another aspect, the selection algorithm module 909 may prompt 924 the UE 902 to select an antenna based on a pre-determined antenna hopping pattern (e.g., antenna 0, then 1, then 0, then 1, etc.). In another aspect, the selection algorithm module 909 may prompt 924 the UE 902 to use an antenna that was most recently previously successfully used.

At block 806, the UE may perform the Access procedure. In an aspect, transmission module 912 may perform the access procedure using the selected 924 antenna. After successful completion of the access procedure, application 911 data 926 may be transmitted, via transmission module 912, to a network entity 430.

FIG. 9 is a conceptual data flow diagram 900 illustrating the data flow between different modules/means/components in an example apparatus 902. The apparatus may be a service layer module associated with a wireless device (e.g., UE 110, UE 202, wireless device 402, etc.). As noted above with respect to the flowcharts describe in FIGS. 7 and 8, the apparatus 902 may include a reception module 904 associated with two or more antennas 906, an access procedure module 908 including one or more selection algorithm modules 909, an application processing module 910 supporting one or more applications 911, and a transmission module 912.

The apparatus may include additional modules that perform each of the steps of the algorithm in the aforementioned call flows and/or flow chart of FIGS. 7 and 8. As such, each step in the aforementioned FIGS. 7 and 8 may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 10 is a diagram 1000 illustrating an example of a hardware implementation for an apparatus 902′ employing a processing system 1014. The processing system 1014 may be implemented with a bus architecture, represented generally by the bus 1024. The bus 1024 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1014 and the overall design constraints. The bus 1024 links together various circuits including one or more processors and/or hardware modules, represented by the processor 1004, the modules 904, 908, 909, 910, 812, and the computer-readable medium 1006. The bus 1024 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1014 may be coupled to a transceiver 1010. The transceiver 1010 is coupled to two or more antennas 1020. The transceiver 1010 provides a means for communicating with various other apparatus over a transmission medium. The processing system 1014 includes a processor 1004 coupled to a computer-readable medium 1006. The processor 1004 is responsible for general processing, including the execution of software stored on the computer-readable medium 1006. The software, when executed by the processor 904, causes the processing system 1014 to perform the various functions described supra for any particular apparatus. The computer-readable medium 1006 may also be used for storing data that is manipulated by the processor 1004 when executing software. The processing system further includes at least one of the modules 904, 908, 909, 910, and 912. The modules may be software modules running in the processor 1004, resident/stored in the computer-readable medium 1006, one or more hardware modules coupled to the processor 1004, or some combination thereof In an aspect, the processing system 1014 may be a component of the UE 350 and may include the memory 360 and/or at least one of the TX processor 368, the RX processor 356, and the controller/processor 359.

In a configuration, the apparatus 902/902′ for wireless communication includes means for obtaining, by a UE, receive chain measurements for two or more antennas associated with the UE when an access procedure is initiated, means for selecting an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure, and means for performing the access procedure using the selected antenna. In an aspect, apparatus 902/902′ may include means for determining that the performed access procedure was unsuccessful. In such an aspect, apparatus 902/902′ means for selecting may be further configured to select a new antenna from the two or more antennas based on one or more subsequent try selection criteria. Further, in such an aspect, apparatus 902/902′ means for performing may be further configured to perform the access procedure using the selected new antenna. In such an aspect, apparatus 902/902′ may include means for determining that the access procedure is to be initiated.

In another configuration, the apparatus 902/902′ for wireless communication includes means for determining that an Access procedure is to be initiated, means for selecting an antenna, from the two or more antennas, for transmission based on a selection algorithm, and means for performing the Access procedure based using the selected antenna. In an aspect, the selection algorithm may include randomly selecting the antenna from the two or more antennas. In an aspect, the selection algorithm may include selecting the antenna based on a hopping pattern among the two or more antennas. In an aspect, the selection algorithm may include selecting the antenna based on an antenna that was most recently successfully used for the Access procedure.

As described supra, the processing system 1014 may include the TX Processor 368, the RX Processor 356, and the controller/processor 359. As such, in one configuration, the aforementioned means may be the TX Processor 368, the RX Processor 356, and the controller/processor 359 configured to perform the functions recited by the aforementioned means.

It is understood that the specific order or hierarchy of steps in the processes disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged. Further, some steps may be combined or omitted. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”

Claims

1. A method of communications for a user equipment (UE), comprising: obtaining, by a UE, receive chain measurements for two or more antennas associated with the UE when an access procedure is initiated;selecting an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure; andperforming the access procedure using the selected antenna.

2. The method of claim 1, wherein the receive chain measurements comprise at least one of: a receive signal code power (RSCP) measurement;a Reference Signal Received Power (RSRP) measurement;a Received Signal Strength Indication (RSSI) measurement; oran automatic gain control (AGC) measurement.

3. The method of claim 1, wherein the UE is configured to operate in at least one of a long term evolution (LTE) based access network, a Universal Mobile Telecommunications System (UMTS) based network, or a code division multiple access (CDMA) based network, and wherein the access procedure is a access channel (ACH) procedure.

4. The method of claim 3, wherein the receive chain measurements are obtained and the antenna selection is performed once for a ACH cycle.

5. The method of claim 3, wherein the receive chain measurements are obtained and the antenna selection is performed prior to an onset of each preamble in a ACH cycle.

6. The method of claim 1, further comprising: determining that the performed access procedure was unsuccessful;selecting a new antenna from the two or more antennas based on one or more subsequent try selection criteria; andperforming the access procedure using the selected new antenna.

7. The method of claim 6, wherein the one or more subsequent try selection criteria comprise at least one of: a greatest receive chain measurement value based on newly performed receive chain measurements;a next greatest receive chain measurement value based on previously performed receive chain measurements;an antenna different than the previously selected antenna, where the two or more antennas comprises two antennas;an antenna from a pool of antennas that does not include the previously selected antenna, where the two or more antennas comprises more than two antennas; ora random antenna selection.

8. The method of claim 1, further comprising: determining that the access procedure is to be initiated.

9. The method of claim 8, wherein the determination that the access procedure is to be initiated is based on reception of a paging indicator.

10. The method of claim 8, wherein the determination that the access procedure is to be initiated is based on internal reception of a message to prompt the UE to engage in a mobile originated (MO) call.

11. The method of claim 1, wherein the UE is configured to operate is a 1x based access network, and wherein the access procedure is an access probe procedure.

12. A method of method of communications for a user equipment (UE), comprising: determining that an Access procedure is to be initiated;selecting an antenna, from the two or more antennas, for transmission based on a selection algorithm; andperforming the Access procedure based using the selected antenna.

13. The method of claim 12, wherein the selection algorithm comprises randomly selecting the antenna from the two or more antennas.

14. The method of claim 12, wherein the selection algorithm comprises selecting the antenna based on a hopping pattern among the two or more antennas.

15. The method of claim 12, wherein the selection algorithm comprises selecting the antenna based on an antenna that was most recently successfully used for the Access procedure.

16. An apparatus for communications by a user equipment (UE), comprising: means for obtaining, by a UE, receive chain measurements for two or more antennas associated with the UE when an access procedure is initiated;means for selecting an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure; andmeans for performing the access procedure using the selected antenna.

17. An apparatus for communications by a user equipment (UE), comprising: means for determining that an Access procedure is to be initiated;means for selecting an antenna, from the two or more antennas, for transmission based on a selection algorithm; andmeans for performing the Access procedure based using the selected antenna.

18. A computer program product, comprising: a non-transitory computer-readable medium comprising code for: obtaining, by a UE, receive chain measurements for two or more antennas associated with the UE when an access procedure is initiated;selecting an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure; andperforming the access procedure using the selected antenna.

19. A computer program product, comprising: a non-transitory computer-readable medium comprising code for: determining, by a user equipment (UE), that an Access procedure is to be initiated;selecting an antenna, from the two or more antennas, for transmission based on a selection algorithm; andperforming the Access procedure based using the selected antenna.

20. An apparatus for communications, comprising: a processing system configured to: obtain, by a UE, receive chain measurements for two or more antennas associated with the UE when an access procedure is initiated;select an antenna, of the two or more antennas, for transmission based on receive chain measurements for use during at least a portion of the access procedure; andperform the access procedure using the selected antenna.

21. The apparatus of claim 20, wherein the receive chain measurements comprise at least one of: a receive signal code power (RSCP) measurement;a Reference Signal Received Power (RSRP) measurement;a Received Signal Strength Indication (RSSI) measurement; oran automatic gain control (AGC) measurement.

22. The apparatus of claim 20, wherein the UE is configured to operate in at least one of a long term evolution (LTE) based access network, a Universal Mobile Telecommunications System (UMTS) based network, or a code division multiple access (CDMA) based network, and wherein the access procedure is a access channel (ACH) procedure.

23. The apparatus of claim 22, wherein the receive chain measurements are obtained and the antenna selection is performed once for a ACH cycle.

24. The apparatus of claim 22, wherein the receive chain measurements are obtained and the antenna selection is performed prior to an onset of each preamble in a ACH cycle.

25. The apparatus of claim 20, wherein the processing system is further configure to: determine that the performed access procedure was unsuccessful;select a new antenna from the two or more antennas based on one or more subsequent try selection criteria; andperform the access procedure using the selected new antenna.

26. The apparatus of claim 25, wherein the one or more subsequent try selection criteria comprise at least one of: a greatest receive chain measurement value based on newly performed receive chain measurements;a next greatest receive chain measurement value based on previously performed receive chain measurements;an antenna different than the previously selected antenna, where the two or more antennas comprises two antennas;an antenna from a pool of antennas that does not include the previously selected antenna, where the two or more antennas comprises more than two antennas; ora random antenna selection.

27. The apparatus of claim 20, wherein the processing system is further configure to: determine that the access procedure is to be initiated.

28. The apparatus of claim 27, wherein the determination that the access procedure is to be initiated is based on reception of a paging indicator.

29. The apparatus of claim 27, wherein the determination that the access procedure is to be initiated is based on internal reception of a message to prompt the UE to engage in a mobile originated (MO) call.

30. The apparatus of claim 20, wherein the UE is configured to operate is a 1X based access network, and wherein the access procedure is an access probe procedure.

31. An apparatus for communications, comprising: a processing system configured to: determine, by a user equipment (UE), that an Access procedure is to be initiated;select an antenna, from the two or more antennas, for transmission based on a selection algorithm; andperform the Access procedure based using the selected antenna.

32. The apparatus of claim 31, wherein the processing system is further configure to randomly select the antenna from the two or more antennas.

33. The apparatus of claim 31, wherein the processing system is further configure to select the antenna based on a hopping pattern among the two or more antennas.

34. The apparatus of claim 31, wherein the processing system is further configure to select the antenna based on an antenna that was most recently successfully used for the Access procedure.