Methods and apparatus for accessing dormant cells

A method, a computer program product, and an apparatus are provided. The apparatus may be a UE. The UE receives an information block from a first base station while camped on a second base station. In an aspect, the information block includes an indication of a random access configuration for performing at least a part of a random access procedure. The UE determines to reselect to the first base station from the second base station. The UE performs at least a part of a random access procedure with the first base station based on the indicated random access configuration to reselect from a second base station to the first base station.

BACKGROUND

The present disclosure relates generally to communication systems, and more particularly, to an access procedure for dormant cells.

SUMMARY

In an aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The apparatus may be a user equipment (UE). The UE receives an information block from a first base station while camped on a second base station. In an aspect, the information block includes an indication of a random access configuration for performing at least a part of a random access procedure. The UE determines to reselect to the first base station from the second base station. The UE performs at least a part of a random access procedure with the first base station based on the indicated random access configuration to reselect from a second base station to the first base station.

In an aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The apparatus may be an eNB. The eNB transmits an information block to a UE while the UE is camped on a second base station. In an aspect, the information block includes a random access configuration for performing at least a part of a random access procedure. The eNB performs, with the UE, at least a part of a random access procedure based on the indicated random access configuration.

In an aspect, the information block includes a cell identifier, the random access procedure being indicated by the cell identifier. In an aspect, the information block is a master information block (MIB). In an aspect, the information block is a system information block (SIB). In such an aspect, the information block is a SIB1(SIB1). In such an aspect, the information block is a subset of a SIB1(SIB1).

In an aspect, the eNB sends system information during the random access procedure. In an aspect, the system information is sent in a random access response to the UE, the system information indicating a second random access configuration for performing a remaining part of the random access procedure. In an aspect, the eNB receives a layer 2 (L2)/layer 3 (L3) (L2/L3) message from the UE based on the system information sent in the random access response. In an aspect, the eNB receives, from a second base station, a configuration for subframes to utilize in data transmissions with the UE.

In an aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The apparatus may be a UE. The UE receives a system information block (SIB) from a base station. In an aspect, the SIB includes a subset of information included in a SIB1(SIB1). The SIB includes cell access related information and cell selection information. The UE performs a random access procedure with the base station based on the received SIB.

In an aspect, the SIB is received from the base station in a dormant state, and the method further includes receiving a second SIB from the base station in an active state after performing the random access procedure, the SIB including a subset of information included in the second SIB. In such an aspect, the SIB is received with a first periodicity and the second SIB is received with a second periodicity greater than the first periodicity. In an aspect, the SIB further includes a random access configuration for performing at least a part of the random access procedure.

DETAILED DESCRIPTION

The E-UTRAN includes the evolved Node B (eNB)106and other eNBs108, and may include a Multicast Coordination Entity (MCE)128. The eNB106provides user and control planes protocol terminations toward the UE102. The eNB106may be connected to the other eNBs108via a backhaul (e.g., an X2 interface). The MCE128allocates time/frequency radio resources for evolved Multimedia Broadcast Multicast Service (MBMS) (eMBMS), and determines the radio configuration (e.g., a modulation and coding scheme (MCS)) for the eMBMS. The MCE128may be a separate entity or part of the eNB106. The eNB106may also be referred to as a base station, a Node B, an access point, 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 eNB106provides an access point to the EPC110for a UE102. Examples of UEs102include 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, a tablet, or any other similar functioning device. The UE102may 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 eNB106is connected to the EPC110. The EPC110may include a Mobility Management Entity (MME)112, a Home Subscriber Server (HSS)120, other MMEs114, a Serving Gateway116, a Multimedia Broadcast Multicast Service (MBMS) Gateway124, a Broadcast Multicast Service Center (BM-SC)126, and a Packet Data Network (PDN) Gateway118. The MME112is the control node that processes the signaling between the UE102and the EPC110. Generally, the MME112provides bearer and connection management. All user IP packets are transferred through the Serving Gateway116, which itself is connected to the PDN Gateway118. The PDN Gateway118provides UE IP address allocation as well as other functions. The PDN Gateway118and the BM-SC126are connected to the IP Services122. The IP Services122may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services. The BM-SC126may provide functions for MBMS user service provisioning and delivery. The BM-SC126may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a PLMN, and may be used to schedule and deliver MBMS transmissions. The MBMS Gateway124may be used to distribute MBMS traffic to the eNBs (e.g.,106,108) belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

FIG. 2is a diagram illustrating an example of an access network200in an LTE network architecture. In this example, the access network200is divided into a number of cellular regions (cells)202. One or more lower power class eNBs208may have cellular regions210that overlap with one or more of the cells202. The lower power class eNB208may be a femto cell (e.g., home eNB (HeNB)), pico cell, micro cell, or remote radio head (RRH). The macro eNBs204are each assigned to a respective cell202and are configured to provide an access point to the EPC110for all the UEs206in the cells202. There is no centralized controller in this example of an access network200, but a centralized controller may be used in alternative configurations. The eNBs204are responsible for all radio related functions including radio bearer control, admission control, mobility control, scheduling, security, and connectivity to the serving gateway116. An eNB may support one or multiple (e.g., three) cells (also referred to as a sectors). The term “cell” can refer to the smallest coverage area of an eNB and/or an eNB subsystem serving are particular coverage area. Further, the terms “eNB,” “base station,” and “cell” may be used interchangeably herein.

Channel estimates derived by a channel estimator658from a reference signal or feedback transmitted by the eNB610may be used by the TX processor668to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor668may be provided to different antenna652via separate transmitters654TX. Each transmitter654TX may modulate an RF carrier with a respective spatial stream for transmission.

A cell may be dormant or may change to a dormant state (mode) to conserve power, to reduce interference to neighboring cells and/or UEs served by neighboring cells, and/or to reduce received handoffs of high mobility UEs that may be likely to experience a radio link failure (RLF) with the cell. A dormant cell may be referred to as a dormant eNB, a new carrier type (NCT) dormant eNB, or an NCT dormant cell. For an UE in an RRC-connected state, a UE measurement report may need to contain a global cell identifier (ID). An UE in an RRC idle state (e.g., an RRC-idle UE) may need to be able to access a dormant cell after receiving a page from an active cell on which the UE is camping.

FIG. 7is a call flow diagram700illustrating an exemplary access procedure for a dormant eNB702by a UE701in communication with and camped on an active cell703. The dormant eNB702transmits sparse overhead signals on overhead channels. Overhead signals include a primary synchronization signal (PSS), secondary synchronization signal (SSS), a position reference signal (PRS), a channel state information (CSI) reference signal (RS) (CSI-RS), CRS, a master information block (MIB), and system information blocks (SIBs). The dormant eNB702transmits the overhead signals on a small subset of subframes within each radio frame or within each of a plurality of radio frames. The sparse transmission of overhead signals contains sufficient information for allowing a UE701in an RRC connected state with an active eNB703(also referred to as a serving eNB) to detect and to measure the dormant eNB702. The access procedure in the diagram700applies to RRC idle UEs that cannot camp on the dormant eNB702.

The dormant eNB702sends overhead channel transmissions in bursts. The bursts are at a reduced periodicity. The dormant eNB702may transmit the PSS, the SSS, the PRS, the CSI-RS, the CRS, the MIB, and the system information (SI) in SI blocks (SIBs) in N ms bursts every M ms with L ms offset. The values for N, M, and L may be configured by the active eNB703. The active eNB703may configure the values for N, M, and L through a broadcast in SI and/or through unicast RRC signaling. The active eNB703may signal the UE701to look at multiple burst configurations to acquire the overhead signals from the dormant eNB702. The System Frame Number (SFN) may be synchronized with neighboring cells by, for example, over-the-air (OTA) synchronization, backhaul based synchronization, or the like. Alternatively, the dormant eNB702may have an SFN/subframe offset from the neighboring cells.

The dormant eNB702may sparsely transmit a MIB and SIBs. The dormant eNB702may transmit only a subset of the information that the dormant eNB702normally transmits when the eNB702is active or in an active state. For example, the dormant eNB702may transmit a SIB1(SIB1) lite, which includes only a subset of the information normally included in a SIB1. Transmitting SI sparsely (e.g., with less periodicity) reduces the coverage of discovery of the dormant eNB702.

The system bandwidth of the dormant eNB702may be the same as the active eNB703. If the system bandwidth of the dormant eNB702is different, the system bandwidth of the dormant eNB702may be communicated in the MIB. The SFN/subframe offset of the dormant eNB702may be the same as the active eNB703. If the SFN/subframe offset is different for the dormant eNB702, the active eNB703may signal the difference to the UE701. The dormant eNB702overhead channel transmission may include an indication that the eNB702is dormant or in a dormant state. The indication may be transmitted in a MIB, SI (e.g., SIB1), or SIB1lite. The indication allows the UE701to determine on what subframes the UE701can detect the dormant eNB702.

In order for the UE701to access the dormant eNB702, the dormant eNB702sends the UE701information that the UE701may use to access the dormant eNB702. When the eNB702is in a dormant state, the dormant eNB702is configured to transmit overhead signals with reduce periodicity at720. The UE701acquires at722parameters for overhead channels of the dormant eNB702from the active eNB703while continuing to monitor the paging channel from the active eNB703. The parameters indicate the resources (e.g., subframes, periodicity) on which the overhead signals can be obtained from the dormant eNB702. On the indicated resources, the UE701receives the PSS and the SSS, and detects the dormant eNB702based on the received PSS and the SSS. On the indicated resources, the UE701also receives CRS and a cell identifier associated with the dormant eNB702. The cell identifier may be a global cell identifier or an extended cell identifier. The UE701determines a reference signal received quality (RSRQ), a reference signal received power (RSRP), or a signal to interference plus noise ratio (SINR) of the CRS received at the burst locations (e.g., 10 ms every 200 ms).

RRC idle UEs perform measurements of neighboring cells at the burst locations. For example, a dormant cell may transmit the overhead signal on the overhead channel for 10 ms every 200 ms. The RRC idle UEs perform cell selection and reselection procedure only on active cells. The UE701in an RRC idle state may read transmitted MIB/SI or SIB1lite information on the dormant cells in order to enable direct access to dormant cells if the idle UE701is in coverage of the dormant cell702. Although the idle UE701can acquire RACH and PRACH configuration to access the dormant eNB702directly, the idle UE701continues to camp on active eNB703. The idle UE701can perform just-in-time reselection and access dormant eNB702in response to a page notification from the active eNB703. In an alternative approach, the idle UE701may initiate the cell reselection on its own before receiving a page notification from the active eNB703.

The active eNB703may communicate at724with the dormant eNB702to configure subframes that the dormant eNB702utilizes for data transmissions and overhead channels when activated. The UE701may acquire SI at726from the dormant eNB702while camped on the active eNB703. The SI may indicate a random access configuration for performing a random access procedure or a part of a random access procedure. The information may be an explicit indication of the random access configuration or may be an implicit indication of the random access configuration. For example, the SI may include a cell identifier and the UE701may determine implicitly the random access configuration based on the cell identifier. Upon receiving a paging notification from the active eNB703at728, the UE701may determine to reselect to the dormant eNB702from the active eNB703. The UE701may make the determination to reselect based on the determined RSRP, RSRQ, and/or SINR of the received CRS or other reference signals.

The UE701may acquire limited SI at726from the dormant eNB702before the UE701initiates a random access procedure with the dormant eNB702. The limited SI can be in a SIB1lite and may provide enough information to the UE701for the UE701to begin the random access procedure by transmitting a PRACH signature sequence to the dormant eNB702. The UE701may need to acquire more information, for example, from the active eNB703, to complete the random access procedure. The random access procedure may be modified to convey remaining SI to the UE701during the random access procedure.

The random access procedure between the idle UE701and dormant eNB702includes several messages, including a message1, random access preamble; a message2, random access response; a message3, L2/L3 message; and a message4, RRC connection reconfiguration message. The UE701initiates the access by transmitting a message1. Message1is a PRACH preamble signature sequence. After receiving the message1at730from the UE701, the dormant eNB702may send a request to the active eNB703for activation before sending a message2, random access response. In another example, the dormant eNB702may send the request for activation to an overlay macro cell before sending the message2, random access response. The dormant eNB702responds to the received message1with a message2, random access response at732. The message2random access response may include additional SI and/or other common parameters necessary for transmission of the message3, L2/L3 message. The UE701prepares the L2/L3 message based on the additional SI and/or other common parameters, and transmits the L2/L3 message to the dormant eNB702at734.

The dormant eNB702responds at736with a message4, RRC connection reconfiguration message. The dormant eNB702then transitions into an active mode and transmits overhead signals with a nominal periodicity, at738. The eNB702transmits overhead signals in the active state with greater periodicity than when in the dormant state. After changing to the active state, the eNB702may indicate in the SI that the eNB702is in the active state rather than the dormant state. In particular, when in the active state, the eNB702may transmit a MIB including an active state indication, system bandwidth, and other information, such as a downlink control channel configuration, a SIB1assignment, etc. The active state indication may include multiple bits to indicate different configurations (e.g., in terms of periodicity and/or bandwidth) of a PSS, an SSS, and reference signals, such as a PRS, a CSI-RS, a CRS, or other reference signals. The nominal periodicity may be less than a periodicity at which overhead signals are transmitted by the active eNB703. Transmitting overhead signals at less periodicity than the active eNB703may be useful in order to limit the interference to UEs being served by the active eNB703, and may be useful to reduce the handover rate of high mobility UEs that have not yet been handed over to the eNB702. High mobility UEs may have a greater likelihood of RLF at the eNB702. Thus, when the eNB702in a dormant state transitions into an active mode, data transmissions may be limited at least initially to configured subframe subsets in order to avoid creating conditions that may lead to RLF of nearby UEs. Radio Resource Management (RRM) and Radio Link Management (RLM) on the active eNB703may also be limited to a set of subframes or resources when the eNB702does not transmit signals.

A number of options exist for the dormant eNB702to provide sufficient information to the idle UE701to allow the UE701to begin the process of reselecting to the dormant eNB702. The options include conveying information through SIB1lite or using the global or enhanced cell ID to implicitly derive the information. When implicit derivation is used, the active eNB703may configure a mapping between the cell ID of the dormant eNB702and the PRACH configuration to be used with that eNB. The dormant eNB702may include the cell ID in the overhead data transmitted by the dormant eNB702. The active eNB may transmit the mapping information to the UE701.

The SIB1lite may include only a subset of information that is normally included in a SIB1. The SIB1lite may include cell access related information and cell selection information. The SIB1lite may further include RACH configuration information. The SIB1lite may include only a subset of the RACH configuration information needed to perform a random access procedure. Specifically, the SIB1lite may include only information necessary for sending a message1, random access preamble. When the SIB-1lite is utilized, the RACH configuration information may be conveyed explicitly or implicitly. For implicit conveyance, the cell identity of the dormant eNB702may be linked to a particular RACH configuration, as discussed supra. For explicit conveyance, as discussed supra, a full RACH configuration may be conveyed or a subset of the RACH configuration may be conveyed.

For example, the SIB1lite that includes the subset of information may have a following example configuration. The UE701in an RRC idle state may assume the following configuration for the dormant eNB702on the same carrier frequency as the active eNB703with respect to the SIB1content.cellAccessRelatedInfoplmn-IdentityList=same as the active celltrackingAreaCode=same as the active cellcellIdentity=included in the SIB1litecellBarred=notBarredintraFreqReselection=allowedcsg-Indication=falsecsg-Identity=not included in the SIB1litecellSelectionInfoq-RxLevMin=included in the SIB1liteq-RxLevMinOffset=included in the SIB1litep-Max=not included or same as the active cellfreqBandIndicator=same as the active cellschedulingInfoList=not included in the SIB1litetdd-Config=not included or same as the active cellsi-WindowLength=not included in the SIB1litesystemInfoValueTag=not included in the SIB1litenonCriticalExtension=not included in the SIB1lite

FIG. 8is a flow diagram800of a method of wireless communication. The method may be performed by a UE, such as the UE701. At802, the UE receives, from a second base station (e.g. active eNB), an indication of resources for detecting a first base station (e.g., dormant eNB). Referring back toFIG. 7, for example, the UE701acquires at722parameters for overhead channels of the dormant eNB702from the active eNB703. As discussed supra, the parameters indicate the resources (e.g., subframes, periodicity) on which the overhead signals can be obtained from the dormant eNB702. At804, the UE receives synchronization signals and an information block from the first base station. The information block includes an indication of a random access configuration for performing at least a part of a random access procedure. Referring back toFIG. 7, for example, the UE701may acquire SI at726from the dormant eNB702while camped on the active eNB703. As discussed supra, the SI may indicate a random access configuration for performing a random access procedure or a part of a random access procedure.

At806, the UE determines if a paging notification is received from the second base station. If a paging notification is received, at step808, the UE determines whether to reselect to the first base station. Referring back toFIG. 7, for example, upon receiving a paging notification from the active eNB703at728, the UE701may determine to reselect to the dormant eNB702from the active eNB703. If the UE determines not to reselect, the UE stays with the second base station. If the UE determines to reselect, at810, the UE performs at least a part of a random access procedure with the first base station based on the indicated random access configuration to reselect from a second base station to the first base station. At812, the UE receives system information during the random access procedure in a random access response from the first base station, the system information indicating a second random access configuration for performing a remaining part of the random access procedure. Referring back toFIG. 7, for example, during the random access procedure between the idle UE701and dormant eNB702, after receiving the message1at730from the UE701, the dormant eNB702may send a request to the active eNB703for activation before sending a message2, random access response. As discussed supra, for example, the dormant eNB702responds to the received message1with a message2, random access response at732. As discussed supra, for example, the message2, random access response may include additional SI and/or other common parameters necessary for transmission of the message3, L2/L3 message.

At814, the UE sends an L2/L3 message to the first base station based on the system information received in the received random access response. As discussed supra, for example, the UE701prepares the L2/L3 message based on the additional SI and/or other common parameters, and transmits the L2/L3 message to the dormant eNB702at734.

The information block received by the UE may include a cell identifier of the first base station. The indication of the random access configuration may be the cell identifier. In such a configuration, the UE determines the random access configuration based on the cell identifier. For example, as discussed supra, the SI acquired from the dormant eNB702may include a cell identifier and the UE701may determine implicitly the random access configuration based on the cell identifier. The information block may be a MIB or a SIB. The information block may be a SIB1. The information block may include a subset of a SIB1and therefore may be a SIB1lite. For example, as discussed supra, the overhead signals transmitted from the dormant eNB702over the overhead channel may include a MIB, SIB1, or SIB1lite.

FIG. 9is a flow diagram900illustrating a method of wireless communication. The method may be performed by a first base station (e.g., dormant eNB). At902, the first base station transmits an information block to a UE while the UE is camped on a second base station. The information block includes an indication of a random access configuration for performing at least a part of a random access procedure. Referring back toFIG. 7, for example, the UE701may acquire SI at726from the dormant eNB702while camped on the active eNB703. As discussed supra, the SI may indicate a random access configuration for performing a random access procedure or a part of a random access procedure.

At904, the first base station performs, with the UE, at least a part of a random access procedure based on the indicated random access configuration. At906, the first base station sends system information during the random access procedure in a random access response to the UE. The system information indicates a second random access configuration for performing a remaining part of the random access procedure. At908, the first base station receives a L2/L3 message from the UE based on the system information sent in the random access response. Referring back toFIG. 7, for example, during the random access procedure between the idle UE701and dormant eNB702, after receiving the message1at730from the UE701, the dormant eNB702may send a request to the active eNB703for activation before sending a message2, random access response. As discussed supra, for example, the dormant eNB702responds to the received message1with a message2, random access response at732. As discussed supra, for example, the message2random access response may include additional SI and/or other common parameters necessary for transmission of the message3, L2/L3 message. As discussed supra, for example, the UE701prepares the L2/L3 message based on the additional SI and/or other common parameters, and transmits the L2/L3 message to the dormant eNB702at734. At910, the first base station may receive, from the second base station, a configuration for subframes to utilize in data transmissions with the UE. Referring back toFIG. 7, for example, the dormant eNB702responds at736with a message4, RRC connection reconfiguration message. As discussed supra, for example, the dormant eNB702then transitions into an active mode and transmits overhead signals with a nominal periodicity, at738.

The information block sent by the first base station may include a cell identifier of the first base station. The indication of the random access configuration may be indicated by the cell identifier. In such a configuration, the UE determines the random access configuration based on the cell identifier. For example, as discussed supra, the SI acquired from the dormant eNB702may include a cell identifier and the UE701may determine implicitly the random access configuration based on the cell identifier. The information block may be a MIB or a SIB. The information block may be a SIB1. The information block may include a subset of a SIB1and therefore may be a SIB1lite. For example, as discussed supra, the overhead signals transmitted from the dormant eNB702over the overhead channel may include a MIB, SIB1, or SIB1lite.

FIG. 10is a flow diagram1000of a method of wireless communication. The method may be performed by a UE, such as the UE701. At1002, the UE receives a SIB from a base station. The SIB includes a subset of information included in a SIB1. The SIB includes cell access related information and cell selection information. At1004, the UE performs at least part of a random access procedure with the base station based on the received SIB. Referring back toFIG. 7, for example, the UE701may acquire limited SI at726from the dormant eNB702before the UE701initiates a random access procedure with the dormant eNB702. As discussed supra, for example, the limited SI can be in a SIB1lite and may provide enough information to the UE701for the UE701to begin the random access procedure by transmitting a PRACH signature sequence to the dormant eNB702. As discussed supra, for example, the SIB1lite may include only a subset of information that is normally included in a SIB1, and may include cell access related information and cell selection information.

At1006, the UE receives the SIB from the base station when the base station is in a dormant state, and receives a second SIB from the base station when the base station is in an active state after performing the random access procedure. The SIB includes a subset of information included in the second SIB. The first SIB received by the UE may be with a first periodicity and the second SIB may be received with a second periodicity greater than the first periodicity. For example, as discussed supra, the UE701may need to acquire more information from the active eNB703, to complete the random access procedure. As discussed supra, for example, the random access procedure may be modified to convey remaining SI to the UE701during the random access procedure.

FIG. 11is a conceptual data flow diagram1100illustrating the data flow between different modules/means/components in an exemplary apparatus1102. The apparatus may be a UE. The apparatus includes a receiving module1204, a transmission module1106, a reselection determination module1108, and a random access procedure module1110.

The receiving module1104receives via1172an information block from a first base station1130while camped on a second base station1150. In an aspect, the information block includes an indication of a random access configuration for performing at least a part of a random access procedure. The reselection determination module1108determines to reselect to the first base station1130from the second base station1150. The reselection determination module1108may indicate to the random access procedure module1110the determination to reselect to the first base station1130via1174. The random access procedure module1110performs at least a part of a random access procedure with the first base station1130based on the indicated random access configuration to reselect from the second base station1150to the first base station1130, via the receiving module1104at1172and1176and via the transmission module1106at1178and1180.

In an aspect, the receiving module1104may receive at1182, from the second base station1150, an indication of resources for detecting the first base station1130. In such an aspect, the information block is received in the indicated resources. In an aspect, the reselection determination module1108may receive, via receiving module1104at1182and1184, a paging notification from the second base station1150. In such an aspect, the determination to reselect is based on the received paging notification.

In an aspect, the information block may include a cell identifier of the first base station1130, the indication of the random access configuration being the cell identifier. In such an aspect, the random access procedure module1110may determine the random access configuration based on the cell identifier. In an aspect, the information block is a MIB. In an aspect, the information block is a SIB. In such an aspect, the information block may be a SIB1. In such an aspect, the information block may be a subset of a SIB1.

In an aspect, the random access procedure module1110may receive, via the receiving module1104at1172and1176, system information during the random access procedure. In an aspect, the system information may be received in a random access response from the first base station1130, the system information indicating a second random access configuration for performing a remaining part of the random access procedure. In an aspect, the random access procedure module1110may send, via the transmission module1106at1178and1180, an L2/L3 message to the first base station1130based on the system information received in the received random access response.

FIG. 12is a diagram1200illustrating an example of a hardware implementation for an apparatus1102′ employing a processing system1214. The processing system1214may be implemented with a bus architecture, represented generally by the bus1224. The bus1224may include any number of interconnecting buses and bridges depending on the specific application of the processing system1214and the overall design constraints. The bus1224links together various circuits including one or more processors and/or hardware modules, represented by the processor1204, the modules1104,1106,1108,1110, and the computer-readable medium/memory1206. The bus1224may 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 system1214may be coupled to a transceiver1210. The transceiver1210is coupled to one or more antennas1220. The transceiver1210provides a means for communicating with various other apparatus over a transmission medium. The transceiver1210receives a signal from the one or more antennas1220, extracts information from the received signal, and provides the extracted information to the processing system1214, specifically the receiving module1104. In addition, the transceiver1210receives information from the processing system1214, specifically the transmission module1106, and based on the received information, generates a signal to be applied to the one or more antennas1220. The processing system1214includes a processor1204coupled to a computer-readable medium/memory1206. The processor1204is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1206. The software, when executed by the processor1204, causes the processing system1214to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory1206may also be used for storing data that is manipulated by the processor1204when executing software. The processing system further includes at least one of the modules1104,1106,1108, and1110. The modules may be software modules running in the processor1204, resident/stored in the computer readable medium/memory1206, one or more hardware modules coupled to the processor1204, or some combination thereof. The processing system1214may be a component of the UE650and may include the memory660and/or at least one of the TX processor668, the RX processor656, and the controller/processor659.

In one configuration, the apparatus1102/1102′ for wireless communication includes means for receiving an information block from a first base station while camped on a second base station, the information block including an indication of a random access configuration for performing at least a part of a random access procedure, means for determining to reselect to the first base station from the second base station, and means for performing at least a part of a random access procedure with the first base station based on the indicated random access configuration to reselect from a second base station to the first base station. The apparatus1102/1102′ may further include means for receiving, from the second base station, an indication of resources for detecting the first base station, where the information block is received in the indicated resources. The apparatus1102/1102′ may further include means for receiving a paging notification from the second base station, where the determination to reselect is based on the received paging notification. In an aspect, the information block may include a cell identifier of the first base station, the indication of the random access configuration being the cell identifier, and the apparatus1102/1102′ may further include means for determining the random access configuration based on the cell identifier. The apparatus1102/1102′ may further include means for receiving system information during the random access procedure. In an aspect, the system information may be received in a random access response from the first base station, the system information indicating a second random access configuration for performing a remaining part of the random access procedure. In such an aspect, apparatus1102/1102′ may further include means for sending an L2/L3 message to the first base station based on the system information received in the received random access response.

The aforementioned means may be one or more of the aforementioned modules of the apparatus1102and/or the processing system1214of the apparatus1102′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1214may include the TX Processor668, the RX Processor656, and the controller/processor659. As such, in one configuration, the aforementioned means may be the TX Processor668, the RX Processor656, and the controller/processor659configured to perform the functions recited by the aforementioned means.