Patent Publication Number: US-2013229965-A1

Title: Paging during connected mode discontinuous reception (drx) operations

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of Indian Patent Application No. 636/DEL/2012, filed Mar. 5, 2012, which is herein incorporated by reference in its entirety. 
     BACKGROUND 
     1. Field 
     Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to techniques for paging during Long Term Evolution (LTE) discontinuous reception (DRX) operations. 
     2. 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), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). UMTS includes a definition for a Radio Access Network (RAN), referred to as UMTS Terrestrial Radio Access Network (UTRAN). 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. For example, third-generation UMTS based on W-CDMA has been deployed all over the world. To ensure that this system remains competitive in the future, 3GPP began a project to define the long-term evolution of UMTS cellular technology. The specifications related to this effort are formally known as Evolved UMTS Terrestrial Radio Access (E-UTRA) and Evolved UMTS Terrestrial Radio Access Network (E-UTRAN), but are more commonly referred to by the project name Long Term Evolution, or LTE for short. 
     E-UTRAN is a RAN standard meant to be a replacement of the UMTS, High-Speed Downlink Packet Access (HSDPA) and High-Speed Uplink Packet Access (HSUPA) technologies specified in 3GPP release 5 and beyond. Unlike HSPA, LTE&#39;s E-UTRA is an entirely new air interface system, unrelated to and incompatible with W-CDMA. It provides higher data rates and lower latency and is optimized for packet data. E-UTRA uses orthogonal frequency-division multiple access (OFDMA) for the downlink and single-carrier frequency-division multiple access (SC-FDMA) on the uplink. In E-UTRAN, the protocol stack functions consist of the Media Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Radio Resource Control (RRC) layers. 
     SUMMARY 
     In an aspect of the disclosure, a method of wireless communication is provided. The method generally includes determining whether one or more paging occasions from a base station (BS) occur while a receiver of an apparatus is in an active state based on a discontinuous reception (DRX) cycle, adjusting a period that the receiver is in the active state during the DRX cycle if at least one paging occasion does not occur while the receiver is in the active state, and monitoring for at least one paging occasion occurring while the receiver is in the active state during the adjusted period. 
     In an aspect of the disclosure, an apparatus for wireless communication is provided. The apparatus generally includes means for determining whether one or more paging occasions from a base station (BS) occur while a receiver of an apparatus is in an active state based on a discontinuous reception (DRX) cycle, means for adjusting a period that the receiver is in the active state during the DRX cycle if at least one paging occasion does not occur while the receiver is in the active state, and means for monitoring for at least one paging occasion occurring while the receiver is in the active state during the adjusted period. 
     In an aspect of the disclosure, an apparatus for wireless communication is provided. The apparatus generally includes at least one processor configured to determine whether one or more paging occasions from a base station (BS) occur while a receiver of an apparatus is in an active state based on a discontinuous reception (DRX) cycle, adjust a period that the receiver is in the active state during the DRX cycle if at least one paging occasion does not occur while the receiver is in the active state, and monitor for at least one paging occasion occurring while the receiver is in the active state during the adjusted period. The apparatus also generally includes a memory coupled with the at least one processor. 
     In an aspect of the disclosure, a computer program product is provided. The computer program product generally includes a non-transitory computer readable medium having instructions stored thereon, the instructions executable by one or more processors for determining whether one or more paging occasions from a base station (BS) occur while a receiver of an apparatus is in an active state based on a discontinuous reception (DRX) cycle, adjusting a period that the receiver is in the active state during the DRX cycle if at least one paging occasion does not occur while the receiver is in the active state, and monitoring for at least one paging occasion occurring while the receiver is in the active state during the adjusted period. 
     Numerous other aspects are provided including apparatus and systems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features, nature, and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein: 
         FIG. 1  illustrates an example wireless communication system according to certain aspects of the present disclosure. 
         FIG. 2  is a block diagram conceptually illustrating an example of an evolved Node B in communication with a user equipment (UE) in a wireless communication system, according to certain aspects of the present disclosure. 
         FIG. 3A  illustrates a cycle that may be followed by a UE that is using a connected mode discontinuous reception (CDRX) method, according to certain aspects of the present disclosure. 
         FIG. 3B  illustrates an adjusted cycle that may be followed by a UE that is using a CDRX method, according to certain aspects of the present disclosure. 
         FIG. 3C  illustrates an adjusted cycle that may be followed by a UE that is using a CDRX method, according to certain aspects of the present disclosure. 
         FIG. 4  illustrates example operations for wireless communications, according to certain aspects of the present disclosure. 
     
    
    
     DESCRIPTION 
     Techniques and apparatus are provided herein for paging during Long Term Evolution (LTE) discontinuous reception (DRX). In some embodiments provided herein, a user equipment (UE) in an active DRX mode monitors for paging occasions from a base station (BS) occurring during the active state duration. The UE monitors for paging occasions by decoding a physical downlink control channel (PDCCH) using a paging-radio network temporary identifier (P-RNTI) associated with a paging occasion unrelated to an international mobile subscriber identity (IMSI) associated with the UE. The UE may then adjust the duration of the active state if a paging occasion does not occur during the active state. Dynamically controlling the length of the DRX active state may reduce power consumption. 
     The techniques described herein may be used for various wireless communication networks such as Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA) networks, etc. The terms “networks” and “systems” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate (LCR). cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as Evolved UTRA (E-UTRA), IEEE 802.11 (WiFi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc. UTRA, E-UTRA, and GSM are part of Universal Mobile Telecommunication System (UMTS). Long Term Evolution (LTE) is an upcoming release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). These various radio technologies and standards are known in the art. For clarity, certain aspects of the techniques are described below for LTE, and LTE terminology is used in much of the description below. 
     Single carrier frequency division multiple access (SC-FDMA) is a transmission technique that utilizes single carrier modulation at a transmitter side and frequency domain equalization at a receiver side. SC-FDMA has similar performance and essentially the same overall complexity as those of OFDMA. However, an SC-FDMA signal has lower peak-to-average power ratio (PAPR) because of its inherent single carrier structure. SC-FDMA has drawn great attention, especially in uplink communications where lower PAPR greatly benefits the mobile terminal in terms of transmit power efficiency. It is currently a working assumption for uplink multiple access scheme in 3GPP LTE, LTE-A, and E-UTRA. 
     AN EXAMPLE WIRELESS COMMUNICATION SYSTEM 
     Referring to  FIG. 1 , a multiple access wireless communication system according to one aspect is illustrated. An access point  100  (AP) includes multiple antenna groups, one including antenna  104  and antenna  106 , another including antenna  108  and antenna  110 , and yet another including antenna  112  and antenna  114 . In  FIG. 1 , only two antennas are shown for each antenna group; however, more or fewer antennas may be utilized for each antenna group. Access terminal  116  (AT) is in communication with antennas  112  and  114 , where antennas  112  and  114  transmit information to access terminal  116  over forward link  120  (also known as a downlink) and receive information from access terminal  116  over reverse link  118  (also known as an uplink). Access terminal  122  is in communication with antennas  106  and  108 , where antennas  106  and  108  transmit information to access terminal  122  over forward link  126  and receive information from access terminal  122  over reverse link  124 . In an FDD system, communication links  118 ,  120 ,  124 , and  126  may use different frequencies for communication. For example, forward link  120  may use a different frequency then that used by reverse link  118 . 
     Each group of antennas and/or the area in which they are designed to communicate is often referred to as a sector of the access point. In an aspect, antenna groups each are designed to communicate to access terminals in a sector, of the areas covered by the access point  100 . 
     In communication over forward links  120  and  126 , the transmitting antennas of the access point  100  utilize beamforming in order to increase the signal-to-noise ratio (SNR) of forward links for the different access terminals  116  and  122 . Also, an access point using beamforming to transmit to access terminals scattered randomly through the access point&#39;s coverage area causes less interference to access terminals in neighboring cells than an access point transmitting through a single antenna to all the access point&#39;s access terminals. 
     An access point (AP) may be a fixed station used for communicating with the terminals and may also be referred to as a base station (BS), a Node B, an evolved Node B (eNB), or some other terminology. An access terminal may also be called a mobile station (MS), user equipment (UE), a wireless communication device, terminal, user terminal (UT), or some other terminology. 
       FIG. 2  is a block diagram of an aspect of a transmitter system  210  (e.g., also known as an access point) and a receiver system  250  (e.g., also known as an access terminal) in wireless communication system  200 , such as a MIMO system. At the transmitter system  210 , traffic data for a number of data streams is provided from a data source  212  to a transmit (TX) data processor  214 . 
     In an aspect, each data stream is transmitted over a respective transmit antenna. TX data processor  214  formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data. 
     The coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (i.e., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by processor  230 . 
     The modulation symbols for all data streams are then provided to a TX MIMO processor  220 , which may further process the modulation symbols (e.g., for OFDM). TX MIMO processor  220  then provides N T  modulation symbol streams to N T  transmitters (TMTR)  222   a  through  222   t.  In certain aspects, TX MIMO processor  220  applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted. 
     Each transmitter  222  receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. N T  modulated signals from transmitters  222   a  through  222   t  are then transmitted from N T  antennas  224   a  through  224   t,  respectively. 
     At receiver system  250 , the transmitted modulated signals are received by N R  antennas  252   a  through  252   r  and the received signal from each antenna  252  is provided to a respective receiver (RCVR)  254   a  through  254   r.  Each receiver  254  conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream. 
     An RX data processor  260  then receives and processes the N R  received symbol streams from N R  receivers  254  based on a particular receiver processing technique to provide N T  “detected” symbol streams. The RX data processor  260  then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor  260  is complementary to that performed by TX MIMO processor  220  and TX data processor  214  at transmitter system  210 . 
     A processor  270  periodically determines which pre-coding matrix to use. Processor  270  formulates a reverse link message comprising a matrix index portion and a rank value portion. 
     The reverse link message may comprise various types of information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor  238 , which also receives traffic data for a number of data streams from a data source  236 , modulated by a modulator  280 , conditioned by transmitters  254   a  through  254   r,  and transmitted back to transmitter system  210 . 
     At transmitter system  210 , the modulated signals from receiver system  250  are received by antennas  224 , conditioned by receivers  222 , demodulated by a demodulator  240 , and processed by a RX data processor  242  to extract the reverse link message transmitted by the receiver system  250 . Processor  230  then determines which pre-coding matrix to use for determining the beamforming weights and then processes the extracted message. 
     In an aspect, logical channels are classified into Control Channels and Traffic Channels. Logical Control Channels comprise Broadcast Control Channel (BCCH), which is a downlink (DL) channel for broadcasting system control information. Paging Control Channel (PCCH) is a DL channel that transfers paging information. Multicast Control Channel (MCCH) is a point-to-multipoint DL channel used for transmitting Multimedia Broadcast and Multicast Service (MBMS) scheduling and control information for one or several MTCHs. Generally, after establishing a Radio Resource Control (RRC) connection, this channel is only used by UEs that receive MBMS (Note: old MCCH+MSCH). Dedicated Control Channel (DCCH) is a point-to-point bi-directional channel that transmits dedicated control information used by UEs having an RRC connection. In an aspect, Logical Traffic Channels comprise a Dedicated Traffic Channel (DTCH), which is a point-to-point bi-directional channel, dedicated to one UE, for the transfer of user information. Also, a Multicast Traffic Channel (MTCH) is a point-to-multipoint DL channel for transmitting traffic data. 
     In an aspect, Transport Channels are classified into DL and uplink (UL). DL Transport Channels comprise a Broadcast Channel (BCH), Downlink Shared Data Channel (DL-SDCH), and a Paging Channel (PCH), the PCH for support of UE power saving (DRX cycle is indicated by the network to the UE), broadcasted over entire cell and mapped to physical layer (PHY) resources which can be used for other control/traffic channels. The UL Transport Channels comprise a Random Access Channel (RACH), a Request Channel (REQCH), an Uplink Shared Data Channel (UL-SDCH), and a plurality of PHY channels. The PHY channels comprise a set of DL channels and UL channels. 
     The DL PHY channels, for example, comprise: 
     Common Pilot Channel (CPICH) 
     Synchronization Channel (SCH) 
     Common Control Channel (CCCH) 
     Shared DL Control Channel (SDCCH) 
     Multicast Control Channel (MCCH) 
     Shared UL Assignment Channel (SUACH) 
     Acknowledgement Channel (ACKCH) 
     DL Physical Shared Data Channel (DL-PSDCH) 
     UL Power Control Channel (UPCCH) 
     Paging Indicator Channel (PICH) 
     Load Indicator Channel (LICH) 
     The UL PHY Channels, for example, comprise: 
     Physical Random Access Channel (PRACH) 
     Channel Quality Indicator Channel (CQICH) 
     Acknowledgement Channel (ACKCH) 
     Antenna Subset Indicator Channel (ASICH) 
     Shared Request Channel (SREQCH) 
     UL Physical Shared Data Channel (UL-PSDCH) 
     Broadband Pilot Channel (BPICH) 
     In an aspect, a channel structure is provided that preserves low PAR (at any given time, the channel is contiguous or uniformly spaced in frequency) properties of a single carrier waveform. 
     For the purposes of the present document, the following abbreviations apply: 
     AM Acknowledged Mode 
     AMD Acknowledged Mode Data 
     ARQ Automatic Repeat Request 
     BCCH Broadcast Control CHannel 
     BCH Broadcast CHannel 
     C—Control 
     CCCH Common Control CHannel 
     CCH Control CHannel 
     CCTrCH Coded Composite Transport Channel 
     CP Cyclic Prefix 
     CRC Cyclic Redundancy Check 
     CTCH Common Traffic CHannel 
     DCCH Dedicated Control CHannel 
     DCH Dedicated CHannel 
     DL DownLink 
     DSCH Downlink Shared CHannel 
     DTCH Dedicated Traffic CHannel 
     FACH Forward link Access CHannel 
     FDD Frequency Division Duplex 
     L1 Layer 1 (physical layer) 
     L2 Layer 2 (data link layer) 
     L3 Layer 3 (network layer) 
     LI Length Indicator 
     LSB Least Significant Bit 
     MAC Medium Access Control 
     MBMS Multimedia Broadcast Multicast Service 
     MCCH MBMS point-to-multipoint Control CHannel 
     MRW Move Receiving Window 
     MSB Most Significant Bit 
     MSCH MBMS point-to-multipoint Scheduling CHannel 
     MTCH MBMS point-to-multipoint Traffic CHannel 
     PCCH Paging Control CHannel 
     PCH Paging CHannel 
     PDU Protocol Data Unit 
     PHY PHYsical layer 
     PhyCH Physical CHannels 
     RACH Random Access CHannel 
     RB Resource Block 
     RLC Radio Link Control 
     RRC Radio Resource Control 
     SAP Service Access Point 
     SDU Service Data Unit 
     SHCCH SHared channel Control CHannel 
     SN Sequence Number 
     SUFI SUper FIeld 
     TCH Traffic CHannel 
     TDD Time Division Duplex 
     TFI Transport Format Indicator 
     TM Transparent Mode 
     TMD Transparent Mode Data 
     TTI Transmission Time Interval 
     U—User 
     UE User Equipment 
     UL UpLink 
     UM Unacknowledged Mode 
     UMD Unacknowledged Mode Data 
     UMTS Universal Mobile Telecommunications System 
     UTRA UMTS Terrestrial Radio Access 
     UTRAN UMTS Terrestrial Radio Access Network 
     MBSFN multicast broadcast single frequency network 
     MCE MBMS coordinating entity 
     MCH multicast channel 
     DL-SCH downlink shared channel 
     MSCH MBMS control channel 
     PDCCH physical downlink control channel 
     PDSCH physical downlink shared channel 
     EXAMPLE DRX MODE OPERATIONS 
     With the ever-increasing popularity of smart phones, there are many new challenges for the design of wireless systems, including power consumption and signaling demands. For example, instead of being awake only for the typically small percentage of talk time, smart phones are awake much more often. Applications, such as e-mail or social networking, may send “keep-alive” message every 20 to 30 minutes, for example. Such applications often use many small and bursty data transmissions that may entail a significantly larger amount of control signaling. Some system level evaluations have identified control channel limitations in addition to traffic channel limitations. 
     Discontinuous Reception (DRX) is a method used in mobile communication to reduce power consumption, thereby conserving the battery of the mobile device. The mobile device and the network negotiate phases in which data transfer occurs, where the mobile device&#39;s receiver is turned on (e.g., in a connected state). During other times, the mobile device turns its receiver off and enters a low power state. There is usually a function designed into the protocol for this purpose. For example, the transmission may be structured in slots with headers containing address details so that devices may listen to these headers in each slot to decide whether the transmission is relevant to the devices or not. In this case, the receiver may only be active at the beginning of each slot to receive the header, conserving battery life. Other DRX techniques include polling, whereby the device is placed into standby for a given amount of time and then a beacon is sent by the base station periodically to indicate if there is any data waiting for it. 
     In LTE, DRX is controlled by the RRC protocol. RRC signaling sets a cycle where the UE&#39;s receiver is operational for a certain period, typically when all the scheduling and paging information is transmitted. The serving evolved Node B (eNB) may know that the UE&#39;s receiver is completely turned off and is not able to receive anything. Except when in DRX, the UE&#39;s receiver may most likely be active to monitor a Physical Downlink Control CHannel (PDCCH) to identify downlink data. During DRX, the UE&#39;s receiver may be turned off. In LTE, DRX also applies to the RRC_Idle state with a longer cycle time than active mode. 
     There are two RRC states for a UE: (1) RRC_Idle where the radio is not active, but an identifier (ID) is assigned to the UE and tracked by the network; and (2) RRC_Connected with active radio operation having context in the eNB. 
     In active mode, there is a dynamic transition between long DRX and short DRX. Long DRX has a longer “off” duration. Durations for long and short DRX are configured by the RRC protocol. The transition is determined by the eNB (e.g., with MAC commands) or by the UE based on an inactivity timer. For example, a lower duty cycle may be used during a pause in speaking during a voice over Internet protocol (VOIP) call; packets are arriving at a lower rate, so the UE can remain off for a longer period. When speaking resumes, this results in lower latency. Packets are arriving more often, so the DRX interval is reduced during this period. 
     Paging During Connected Mode DRX Operations 
       FIG. 3A  illustrates a cycle that may be followed by a UE that is using a connected mode DRX (CDRX) method, according to certain aspects of the present disclosure. The UE may monitor its own paging occurrence based on a universal subscriber identity module (USIM) international mobile subscriber identity (IMSI) that is unique to the UE. In the case of CDRX, the UE may be allocated an ON duration  302  during which the UE may monitor downlink transmissions such as PDCCH. Outside of the ON duration, the UE may go to sleep mode  304  (opportunity for DRX) for battery saving or to acquire an inter-frequency/inter-radio access technology (RAT) neighbor cell identity if requested by the network to do so and report cell global identity. This mechanism may be used in particular for automatic neighbor cell discovery and automatic neighbor relation within the network where each eNB may update its neighbor list automatically once new cells are added in the network. 
     If a paging occurrence takes place while the UE is in an inactive state  304  based on a periodic DRX cycle (e.g., a sleep mode based on the IMSI associated with the UE), the UE may need to wake up if, in fact, the UE was sleeping and, as a result, there may be a cost in terms of battery consumption. In the scenario when the UE may be attempting to acquire a neighbor cell identity, the DRX cycle may be split into two different parts, and each part may not be long enough for neighbor system information acquisition even though the total DRX time may be long enough to guarantee acquisition if not split. An eNB engaged in an active call with the UE may be unaware of the IMSI associated with the UE. Therefore, the eNB may not be able to select a CDRX long cycle offset such that the UE paging occasion would fall within ON Duration period  302 . Therefore, certain aspects of the present disclosure provide techniques for ensuring that the UE using a CDRX method may not have to awake from sleep mode if a paging occurrence takes place. 
     Paging in connected mode may have at least two purposes: to inform the UE of a pending change of system information and to indicate whether an earthquake and tsunami warning system (ETWS) and/or commercial mobile alert system (CMAS) notification is present or not. In both scenarios, the eNB may send paging information in all possible paging occasions since the eNB may not have knowledge of which IMSIs are camped under its coverage. In other words, the eNB may be expected to send paging in all system frame numbers (SFNs) and all subframes which correspond to a possible value of Ns=max(1,nB/T) as defined in 3GPP 36.304. 
     As the UE may need to monitor its own paging occasion in IDLE mode (e.g., sleep mode  304 ), any paging occasion may be appropriate for the UE in CONNECTED mode (e.g., ON duration  302 ) for the purposes described above (e.g., to inform the UE of a pending change of system information or to inform of any emergency situation). In other words, instead of monitoring its own paging occasion, the UE may monitor any paging occurrence during the ON duration  302  (or close to the ON duration  302  in case the ON duration  302  is less than the frequency of a paging occasion). As long as the UE monitors a paging occasion at least once every default Paging Cycle (e.g., 1.28 s), the UE may be compliant to 3GPP 36.331 performance requirements. 
       FIGS. 3A-C  illustrate scenarios where periods that a UE is in active state may be adjusted to monitor for a paging occasion, according to certain aspects of the present disclosure. Referring to  FIG. 3A , if a paging occasion subframe  302  is within the ON duration period, the UE may monitor paging in the paging occasion subframe  302  at least every default paging cycle (e.g., 1.28 s). In other words, the UE may attempt to decode PDCCH using P-RNTI in this sub-frame unrelated to the IMSI associated with the UE. Therefore, the UE may not have to awake for paging occasion subframe  304  if the UE is within the default paging cycle that begins at the paging occasion subframe  302 . For certain aspects, paging occasion subframe  302  may be subframe  9  for FDD. 
     If the ON duration is less than the frequency of the paging occasion (e.g., 10 subframes; 10 ms), the UE may adjust the ON duration at least once every default paging cycle so that the paging occasion subframe may be monitored. Referring to  FIG. 3B , the ON duration may be extended, as indicated by  308  to monitor for paging occasion subframe  306 . As another example, referring to  FIG. 3C , the ON duration may be extended to include subframes  312  before the original ON duration (in case of early wakeup for CQI/RI reporting) to monitor for paging occasion subframe  510 . In aspects, the ON duration for two different default paging cycles may be extended as shown in  FIGS. 3B and 3C , respectively. 
     If the CDRX long cycle length is greater than the default paging cycle, the UE may have to monitor multiple paging occasion subframes within the CDRX cycle. In other words, the UE may be required to monitor paging subframes corresponding to the paging subframe monitored during or near ON duration (e.g., the first paging occasion subframe) and paging subframes corresponding to the product of k and the default paging cycle, for k=1, 2, . . . n. In other words, as long as 
       first paging subframe+ k *defaultPagingCycle&lt; CDRX  long cycle length, 
     the additional k paging subframes may be monitored. In this manner, the UE may leave an inactive state (e.g., during the Opportunity for DRX) to monitor a paging occasion at least once every default, or predefined, Paging Cycle. However, the amount of time the UE is not in the ON Duration may be increased and/or optimized. 
     Adjusting the ON duration to monitor for paging occasions may provide a longer battery life as the UE may not have to wake up outside of the CDRX ON duration to monitor paging channel once every defaultPagingCycle. Moreover, adjusting the ON duration may provide a faster inter-frequency/inter-RAT neighbor cell identity acquisition because the idle time within a connected mode DRX cycle may not be interrupted by monitoring the LTE paging occurrence. In other words, more time may be spent on the inter-frequency/inter-RAT cell frequency in order to acquire the set of system information needed for Cell Global Identification reporting. 
       FIG. 4  illustrates example operations  400  for wireless communications, according to certain aspects of the present disclosure. The operations  400  may begin at  402  by determining whether one or more paging occasions from a base station (BS) occur while a receiver of an apparatus is in an active state based on a discontinuous reception (DRX) cycle. At  404 , a period that the receiver is in the active state during the DRX cycle is adjusted if at least one paging occasion does not occur while the receiver is in the active state. At  406 , at least one paging occasion occurring while the receiver is in the active state during the adjusted period is monitored for. 
     As used herein, a phrase referring to “at least one of a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c. 
     The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. Generally, where there are operations illustrated in the figures, those operations may have corresponding counterpart means-plus-function components with similar numbering. 
     More particularly, means for transmitting, means for sending, or means for forwarding may comprise a transmitter, such as the transmitter  254  illustrated in  FIG. 2 . Means for receiving may comprise a receiver, such as the receiver  254  illustrated in  FIG. 2 . Means for determining, means for processing, means for operating, means for detecting, means for performing, or means for transitioning may comprise a processing system having at least one processor, such as the processor  270  illustrated in  FIG. 2 . Means for storing may comprise a memory, such as the memory  272  of  FIG. 2 . 
     It is understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged while remaining within the scope of the present disclosure. 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. 
     Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof 
     Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. 
     The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
     The steps of a method or algorithm described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal In the alternative, the processor and the storage medium may reside as discrete components in a user terminal 
     The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. 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 without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.