Patent Publication Number: US-2013242828-A1

Title: Optimized wakeup for communication devices

Description:
RELATED APPLICATION AND PRIORITY CLAIM 
     This application is related to and claims priority to U.S. Provisional Patent Application Ser. No. 61/553,777, filed Oct. 31, 2011, for “OPTIMIZED WAKEUP” which is incorporated herein by reference for all purposes and as if fully set forth below. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to wireless communication systems. More specifically, the present disclosure relates to systems and methods for optimized wakeup enabling efficient operation of communication devices. 
     BACKGROUND 
     Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, data and so on. These systems may be multiple-access systems capable of supporting simultaneous communication of multiple mobile devices with one or more base stations. 
     Within wireless communications systems, base stations may periodically send page messages to mobile devices residing in wireless networks. Page messages may notify a mobile device of an incoming voice call or give channel assignments to a mobile device. To receive these page messages, the mobile device needs to wake-up from sleep mode. Current wake-up methods can be improved. 
     SUMMARY OF SOME EXAMPLE EMBODIMENTS 
     Devices, systems, articles of manufacture, and methods for optimized wake-up are described. According to one embodiment, a method for optimized wake-up is disclosed. Page messages are received at a page message receiving sub-slot. A wake-up record is updated. Sleep mode is entered. Other aspects, embodiments, and features are also claimed and described. 
     A page message may be detected in a sub-slot with a sub-slot number. The wake-up record may be updated based on the sub-slot number of the sub-slot. The wake-up record may include a stored sub-slot number and a counter. The sub-slot number of the sub-slot may not match the stored sub-slot number. Updating the wake-up record based on the sub-slot number may include resetting the count to 0, and setting the sub-slot number as the stored sub-slot number. The page message receiving sub-slot may be reset to a first sub-slot. 
     Updating the wake-up record may include determining if a sub-slot number of the page message receiving sub-slot matches a stored sub-slot number, and if so incrementing a count. The method may also include determining whether the count is greater than or equal to a consecutive sub-slot threshold. If the count is greater than or equal to the consecutive sub-slot threshold, the method may include adjusting the page message receiving sub-slot to the stored sub-slot number. The consecutive sub-slot threshold may be adjustable. 
     The wake-up record may be for a first PN code, and a method may also include, moving from a first PN code to a second PN code, storing the wake-up record for the first PN code, and determining whether a wake-up record for the second PN code has been created. A wake-up record for the second PN code may have been created and the method may include using the wake-up record for the second PN code. A wake-up record for the second PN code may not have been created, and the method may include generating a wake-up record for the second PN code, setting a stored sub-slot number for the second PN code to a first sub-slot, initializing the page message receiving sub-slot to the first sub-slot, and initializing a count for the wake-up record for the second PN code to 0. 
     The method may be performed by a wireless communication device. The method may increase a sleep time of a wireless communication device. The method may reduce the awake time of one subscription in slotted mode. This can aid to reduce conflicts between dual subscriptions wake-up in dual SIM dual standby devices. The method may improve call performance in a wireless communication device. Call performance may include higher throughput, greater capacity, or improved reliability. The method may be performed by a wireless communication device in at least one of a wireless network and a roaming network. 
     The paging message may be received via a paging channel. The paging message may not be received via a quick paging channel. 
     According to another embodiment, a wireless device configured for optimized wake-up is described. The wireless device includes a processor and executable instructions stored in memory that is in electronic communication with the processor. The wireless device receives page messages at a page message receiving sub-slot. The wireless device also updates a wake-up record. The wireless device additionally enters sleep mode. 
     According to yet another embodiment, a computer-program product for optimized wake-up is described. The computer-program product includes a non-transitory computer-readable medium having instructions thereon. The computer-program product includes instructions for receiving page messages at a page message receiving sub-slot. The computer-program product also includes instructions for updating a wake-up record. The computer-program product further includes instructions for entering sleep mode. 
     According to still yet another embodiment, a wireless communication device configured to periodically wake up for wireless communications is described. The wireless communication device includes a communications interface configured to receive a wireless signal. The wireless communication device includes also a processor. The processor is operatively coupled to the communications interface and is configured to wake up the device if the processor detects a page message in the wireless signal at a pre-determined sub-slot number. The processor is also configured to update a wake-up record. The processor is further configured to return to sleep mode. 
     According to yet another embodiment, a wireless device configured for optimized wake-up is described. The apparatus includes means for receiving page messages at a page message receiving sub-slot. The apparatus also includes means for updating a wake-up record. The apparatus further includes means for entering sleep mode. 
     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  shows an example of a wireless communication system in which embodiments of the present invention disclosed herein may be utilized; 
         FIG. 2  shows a block diagram of a transmitter and a receiver in a wireless communication system according to some embodiments of the present invention; 
         FIG. 3  shows a block diagram of a design of a receiver unit and demodulator at a receiver according to some embodiments of the present invention; 
         FIG. 4  shows a wireless communication system with multiple wireless devices in which embodiments of the present invention disclosed herein may be utilized; 
         FIG. 5  shows a timing diagram of the optimized wake-up mode of a wireless communication device according to some embodiments of the present invention; 
         FIG. 6  shows another timing diagram of the optimized wake-up mode of a wireless communication device according to some embodiments of the present invention; 
         FIG. 7  shows a flow diagram illustrating a method for optimizing wake-up according to some embodiments of the present invention; 
         FIG. 8  shows a flow diagram illustrating a method for optimized wake-up during a switch of pseudonoise (PN) codes according to some embodiments of the present invention; and 
         FIG. 9  shows certain components that may be included within a wireless communication device according to some embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF ALTERNATIVE &amp; EXEMPLARY EMBODIMENTS 
     More and more people are using wireless communication devices, for example, mobile phones, not only for voice but also for data communications. CMDA2000 is one such standard used for providing voice, data, and signaling services to and from wireless communication devices. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc. UTRA includes W-CDMA and Low Chip Rate (LCR) while CDMA2000 covers Interim Standard 2000 (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, IEEE 802.16, IEEE 802.20, Flash-OFDMA, etc. UTRA, E-UTRA and GSM are part of Universal Mobile Telecommunication System (UMTS). Long Term Evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and Long Term Evolution (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). 
     In CDMA2000, a paging channel is used to transmit page messages to wireless communication devices in standby mode (also called idle mode). During standby mode, a wireless communication device continuously consumes power to sustain the circuitry needed to monitor the signals transmitted from a base station. Continual monitoring of the paging channel for page messages in standby mode may significantly deplete battery power. In other words, elongating the time taken to monitor the paging channel results in excess power consumption. Because many wireless communication devices are portable and are powered by an internal battery, prolonging monitoring time unnecessarily consumes power and significantly shortens battery life. Depleted power resources can lead to poor user experience and also failed communications. Thus, reducing standby time on the wireless communication device will reduce power consumption and can aid in providing positive user experience. 
       FIG. 1  shows an example of a wireless communication system  100  in which embodiments of the present invention disclosed herein may be utilized. The wireless communication system  100  includes multiple base stations  102  and multiple wireless communication devices  104 . The wireless communication system  100  may be designed to implement one or more CDMA standards such as CDMA2000 and wideband code division multiple access (W-CDMA) and/or some other standards. 
     Each base station  102  provides communication coverage for a particular geographic area  106 . The term “cell” can refer to a base station  102  and/or its coverage area  106  depending on the context in which the term is used. The terms “networks” and “systems,” as used herein, are sometimes used interchangeably. 
     The terms “wireless communication device” and “base station” utilized in this application can generally refer to an array of components. For example, as used herein, the term “wireless communication device” refers to an electronic device that may be used for voice and/or data communication over a wireless communication system. Examples of wireless communication devices  104  include cellular phones, smart phones, personal digital assistants (PDAs), handheld devices, wireless modems, laptop computers, personal computers, and many other portable or stationary devices capable of wireless communication. A wireless communication device  104  may alternatively be referred to as an access terminal, a mobile terminal, a mobile station, a remote station, a user terminal, a terminal, a subscriber unit, a subscriber station, a mobile device, a wireless device, user equipment (UE) or some other similar terminology. A wireless communication device may be used in a wireless network and/or a roaming network. 
     The term “base station” can refer to a wireless communication station that is installed at a fixed location and used to communicate with wireless communication devices  104 . A base station  102  may alternatively be referred to as an access point (including nano-, pico- and femto-cells), a Node B, an evolved Node B, a Home Node B, or some other similar terminology. In some embodiments, base stations  102  may be mobile and can be repositioned as desired or needed for adequate network coverage. 
     To improve system capacity, a base station coverage area  106  may be partitioned into multiple smaller areas, e.g., three smaller areas  108   a ,  108   b , and  108   c . Each smaller area  108   a ,  108   b ,  108   c  may be served by a respective base transceiver station (BTS). The term “sector” can refer to a BTS and/or its coverage area  106  depending on the context in which the term is used. For a sectorized cell, the BTSs for all sectors of that cell are typically co-located within the base station  102  for the cell. 
     Wireless communication devices (e.g., subscriber stations)  104  are typically dispersed throughout the wireless communication system  100 . A wireless communication device  104  may communicate with one or more base stations  102  on the downlink and/or uplink at any given moment. The downlink (or forward link) refers to the communication link from a base station  102  to a wireless communication device  104 , and the uplink (or reverse link) refers to the communication link from a wireless communication device  104  to a base station  102 . Uplink and downlink may refer to the communication link or to the carriers used for the communication link. 
     For a centralized architecture, a system controller  110  may couple to the base stations  102  and provide coordination and control for the base stations  102 . The system controller  110  may be a single network entity or a collection of network entities. As another example, for a distributed architecture, base stations  102  may communicate with one another as needed. Thus embodiments of the present invention can be used with various network architectures although certain embodiments of the present invention may be discussed herein as relating to CDMA-type networks. 
       FIG. 2  shows a block diagram of a transmitter  211  and a receiver  213  in a wireless communication system  100  according to some embodiments of the present invention. For the downlink, the transmitter  211  may be part of a base station  102  and the receiver  213  may be part of a wireless communication device  104 . For the uplink, the transmitter  211  may be part of a wireless communication device  104  and the receiver  213  may be part of a base station  102 . In some embodiments, receivers and transmitters can be combined or implemented as a transceiver. 
     At the transmitter  211 , a transmit (TX) data processor  234  receives and processes (e.g., formats, encodes, and interleaves) data  238  and provides coded data. The transmit (TX) data processor  234  may also receive page messages from a controller  214 . A modulator  212  performs modulation on the coded data and provides a modulated signal. For IS-95 and CDMA2000 systems, the processing by modulator  212  may include covering coded and pilot data with Walsh codes to channelize user-specific data, messages, and pilot data onto their respective code channels and spreading the channelized data with a pseudorandom number (PN) sequence having a particular PN offset assigned to the base station. A transmitter unit (TMTR)  218  conditions (e.g., filters, amplifies, and upconverts) the modulated signal and generates an RF modulated signal, which is transmitted via an antenna  220 . 
     At the receiver  213 , an antenna  222  receives RF modulated signals from the transmitter  211  and other transmitters. The antenna  222  provides a received RF signal to a receiver unit (RCVR)  224 . The receiver unit  224  conditions (e.g., filters, amplifies, and downconverts) the received RF signal, digitizes the conditioned signal, and provides samples. A demodulator  226  processes the samples as described below and provides demodulated data. For IS-95 and CDMA2000 systems, the processing by demodulator  226  includes despreading the data samples with the same PN sequence used to spread the data at the base station, decovering the despread samples to channelize the received data and messages onto their respective code channels and coherently demodulating the channelized data with a pilot recovered from the received signal. A receive (RX) data processor  228  processes (e.g., deinterleaves and decodes) the demodulated data and provides decoded data  232 . In general, the processing by demodulator  226  and RX data processor  228  is complementary to the processing by the modulator  212  and the TX data processor  234 , respectively, at the transmitter  211 . 
     Controllers/processors  214  and  230  direct operation at the transmitter  211  and receiver  213 , respectively. Memories  216  and  236  store program codes in the form of computer software and data used by the transmitter  211  and receiver  213 , respectively. 
       FIG. 3  shows a block diagram of a design of a receiver unit  324  and a demodulator  326  at a receiver  213  according to some embodiments of the present invention. Within the receiver unit  324 , a receive chain  342  processes the received RF signal and provides I (inphase) and Q (quadrature) baseband signals, which are denoted as I bb  and Q bb . The receive chain  342  may perform low noise amplification, analog filtering, quadrature downconversion, etc. as desired or needed. An analog-to-digital converter (ADC)  344  digitalizes the I and Q baseband signals at a sampling rate of f ad , from a sampling clock  340  and provides I and Q samples, which are denoted as I adc  and Q adc . In general, the ADC sampling rate f adc  may be related to the symbol rate f sym  by any integer or non-integer factor. 
     Within the demodulator  326 , a pre-processor  346  performs pre-processing on the I and Q samples from the analog-to-digital converter (ADC)  344 . For example, the pre-processor  346  may remove direct current (DC) offset, remove frequency offset, etc. An input filter  348  filters the samples from the pre-processor  346  based on a particular frequency response and provides input I and Q samples, which are denoted as I in  and Q in . The input filter  348  may filter the I and Q samples to suppress images resulting from the sampling by the analog-to-digital converter (ADC)  344  as well as jammers. The input filter  348  may also perform sample rate conversion, e.g., from 24× oversampling down to 2× oversampling. A data filter  350  filters the input I and Q samples from the input filter  348  based on another frequency response and provides output I and Q samples, which are denoted as I out  and Q out . The input filter  348  and the data filter  350  may be implemented with finite impulse response (FIR) filters, infinite impulse response (IIR) filters or filters of other types. The frequency responses of the input filter  348  and the data filter  350  may be selected to achieve good performance. In one design, the frequency response of the input filter  348  is fixed and the frequency response of the data filter  350  is configurable. 
     An adjacent-channel-interference (ACI) detector  354  receives the input I and Q samples from the input filter  348 , detects for adjacent-channel-interference (ACI) in the received RF signal and provides an adjacent-channel-interference (ACI) indicator  356  to the data filter  350 . The adjacent-channel-interference (ACI) indicator  356  may indicate whether or not adjacent-channel-interference (ACI) is present and, if present, whether the adjacent-channel-interference (ACI) is due to the higher RF channel centered at +200 kilohertz (kHz) and/or the lower RF channel centered at −200 kHz. The frequency response of the data filter  350  may be adjusted based on the adjacent-channel-interference (ACI) indicator  356 , to achieve desirable performance. 
     An equalizer/detector  352  receives the output I and Q samples from the data filter  350  and performs equalization, matched filtering, detection and/or other processing on these samples. For example, the equalizer/detector  352  may implement a maximum likelihood sequence estimator (MLSE) that determines a sequence of symbols that is most likely to have been transmitted given a sequence of I and Q samples and a channel estimate. 
       FIG. 4  shows a wireless communication system  400  with multiple wireless devices in which embodiments of the present invention disclosed herein may be utilized. The wireless communication system  400  of  FIG. 4  may be one example of the wireless communication system  100  described above in connection with  FIG. 1 . For example, the base station  402  and wireless communication device  404  of  FIG. 4  may correspond to the base station  102  and wireless communication device  104  of  FIG. 1 , respectively. 
     Communications in the wireless communications system  400  (e.g., a multiple-access system) may be achieved through transmissions over one or more wireless links, such as a downlink  480  or an uplink  482 . The communication link may be established via a single-input and single-output (SISO), multiple-input and single-output (MISO) or a multiple-input and multiple-output (MIMO) system. A MIMO system includes transmitter(s) and receiver(s) equipped, respectively, with multiple (N T ) transmit antennas and multiple (N R ) receive antennas for data transmission. SISO and MISO systems are particular instances of a MIMO system. The MIMO system can provide improved performance (e.g., higher throughput, greater capacity or improved reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized. 
     A MIMO system may support both time division duplex (TDD) and frequency division duplex (FDD) systems. In a TDD system, downlink  480  and uplink  482  transmissions are on the same frequency region so that the reciprocity principle allows the estimation of the downlink channel from the uplink channel. This enables a transmitting wireless device to extract transmit beamforming gain from communications received by the transmitting wireless device. 
     The wireless communication system  400  may be a multiple-access system capable of supporting communication with multiple wireless communication devices  404  by sharing available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, wideband code division multiple access (W-CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems and spatial division multiple access (SDMA) systems. 
     A wireless communication device  404  may communicate with zero, one or multiple base stations  402  on the downlink  480  and/or uplink  482  at any given moment. As described above, the downlink  480  (or forward link) refers to the communication link from a base station  402  to a wireless communication device  404 , and the uplink  482  (or reverse link) refers to the communication link from a wireless communication device  404  to a base station  402 . 
     A wireless communication device  404  may operate in several modes or states, such as active mode, standby mode, and inactive mode. In active mode, the wireless communication device can actively exchange data with one or more base stations  402  (e.g., voice or data). In standby mode (i.e., idle mode), the wireless communication device  404  may monitor a paging channel for messages, such as general page messages (GPM) or direct messages addressed to the wireless communication device  404 . In inactive or sleep mode, the wireless communication device  404  reduces power consumption by powering down as much circuitry as possible. In other words, in inactive or sleep mode, the wireless communication device  404  does not monitor the paging channel or perform access procedures. 
     The power consumption by the wireless communication device  404  in the standby mode decreases the available battery resources. This generally shortens the time between battery recharges. Power consumption in the standby mode is typically many times greater than that in the inactive mode. Any reduction in the amount of time spent in the standby mode may result in a direct and significant improvement in overall battery life of the wireless communication device  404 . Therefore, it is desirable to minimize the wireless communication device&#39;s  404  power consumption in the standby mode to increase battery life. Power efficiency and conservation also becomes increasingly important as wireless communication devices become more feature rich. 
     In one configuration, to reduce power consumption in standby mode, messages on the paging channel may be sent to a wireless communication device  404  at designated times. For example, in CDMA2000 systems, the paging channel is divided into numbered “slots” (i.e., a slotted paging channel). Each slot may correlate to a slot cycle index (SCI). 
     The base stations  402  may assign one or more slots to the wireless communication device  404  to receive page messages. For example, under the IS-2000 standard, the paging channel is partitioned into two paging channel slots, each having an 80 millisecond (msec) duration. Each paging channel slot is further partitioned into four 20 msec frames or sub-slots. A group of wireless communication devices  404  may be assigned to each paging channel slot. 
     In a slotted paging channel, the wireless communication device  404  periodically, rather than continuously, monitors the paging channel for messages from the base station  402 . In other words, the wireless communication device  404  may wake up at certain slots (corresponding to the slot cycle index (SCI) assigned to the wireless communication device) to decode page messages. The wireless communication device  404  wakes up from inactive mode prior to its assigned slot or sub-slot, switches into standby mode to detect the page message and enters active mode to processes the paging channel for messages. In other words, the wireless communication device  404  may wake-up at (e.g., just prior to) a pre-determined sub-slot number to process a page message received via wireless signals. The wireless communication device  404  may revert back to inactive mode if additional communication is not required. In this manner, power is conserved by reducing standby mode time. 
     In this configuration, the wireless communication device  404  will remain in the active or awake state if a received message requires the wireless communication device  404  to perform additional actions. When not in a standby or active state, the wireless communication device  404  reverts back to inactive mode. However, this configuration may be problematic because, if the base station  402  sends a page messages to the wireless communication device  404  while in inactive or sleep mode, the page messages will not be detected by the wireless communication device  404 . 
     Additionally, under this configuration, if the base station  402  changes slots or sub-slots in which page messages are sent, the wireless communication device  404  may continuously miss page messages from the base station  402 . Alternatively, if the base station  402  sends page messages in a different slot than currently assigned to the wireless communication device  404 , the wireless communication device  404  may be awake until the page message is detected. In other words, the wireless communication device  404  will be unnecessarily awake for slots in which no page messages are being sent and power will be needlessly wasted. 
     In another configuration of a slotted paging channel, a wireless communication device  404  remains awake for the two 80 msec slots to detect page messages from the base station  402  or until a page message is received. The two slots may each be divided into four 20 msec sub-slots. In this configuration, the wireless communication device  404  may be required to remain awake for eight 20 msec (e.g., 160 msec). 
     In an optimal network, a base station  402  always sends the wireless communication device  404  a page message during the first sub-slot. This will allow the wireless communication device  404  to enter sleep mode shortly after the page message is received. In this way, the time spent in inactive mode is increased because the wireless communication device  404  will not be continuously searching for page messages in standby mode. 
     In a non-optimal network, the base station  402  may send the wireless communication device  404  a page message during a later sub-slot. A base station  402  may send a page message at a later sub-slot to ensure that all wireless communication devices  404  receive the page messages. However, this approach can be inefficient because it causes wireless communication devices  404  remain in standby mode for longer periods than necessary. Thus, when the base station  402  sends a page message to a wireless communication device  404  later than in the first sub-slot, the wireless communication device  404  will remain in standby mode for additional sub-slots for which no information is being received or decoded. For example, if the base station  402  sends the wireless communication device  404  a page message in the eighth sub-slot, the wireless communication device  404  may remain in standby mode unnecessarily for the first seven sub-slots (i.e., 140 msec). 
     In another configuration, a wireless communication device  404  may employ a quick paging channel (QPCH). A QPCH is a separate channel from the paging channel. The QPCH does not receive page messages, but rather is used to detect bits that inform the wireless communication device  404  whether to switch from inactive mode to standby mode to receive a page message on the paging channel. 
     The QPCH is used in conjunction with the paging channel and functions like a control channel for the paging channel. Each QPCH slot is associated with a corresponding paging channel slot, but is transmitted before the associated paging channel slot. For example, slot 2 of the QPCH slot is transmitted 100 milliseconds (msec) before slot 2 of the paging channel. A paging indicator bit, or bits, on the QPCH alerts the wireless communication device  404  that a coded page message is about to be transmitted on the paging channel in the associated paging channel slot. However, the QPCH may fail to receive or decode the paging indication bit(s). In this case, the page message sent to the paging channel will also fail to be received and decoded by the wireless communication device  404 . 
     The QPCH may also send false alarms to the wireless communication device  404 . In the case of a false alarm, the QPCH informs the wireless communication device  404  that a paging message is to be received in the next slot when no paging message is present. This causes the wireless communication device  404  to waste power by operating in standby mode when no page messages are being received. 
     As stated previously, the base station  402  may send a page message to the wireless communication device  404 . The page message may be a direct page message  486  or a general page message. In some instances, the general page message (GPM) may be an empty general page message  488 . Additionally or alternatively, the direct page message  486  may also be a general page message. 
     The base station  402  may include a page message module  484  that generates and sends a direct page message  486  and/or an empty general page message  488  to the wireless communication device  404 . The wireless communication device  404  may also detect the direct page message  486  and/or the empty general page message  488 . The wireless communication device  404  may also detect data for the next message that is not required for the page matching algorithm. 
     Direct page messages  486  may alert the wireless communication device  404  to the presence of incoming call system update parameters (e.g., overhead messages). If the wireless communication device  404  detects a direct page message  486 , the wireless communication device  404  may perform access procedures. 
     An empty general page message (GPM)  488  may indicate that all the direct page messages  486  have been sent by the base station  402 . If the wireless communication device  404  detects an empty general page message  488 , the wireless communication device  404  may immediately go to sleep (e.g., inactive mode) instead of waiting for further page messages. 
     In one configuration in which embodiments of the present invention disclosed herein may be utilized, the wireless communication device  404  can include an optimized wake-up module  460 . The optimized wake-up module  460  can help to increase sleep time. The optimized wake-up module  460  may allow the wireless communication device  404  to adjust the wake-up time of the wireless communication device  404  to a sub-slot later than the first sub-slot. In this manner, the wireless communication device  404  may enter standby mode in the same sub-slot as when the page message is being received. Thus, the amount of time the wireless communication device  404  is unnecessarily in standby mode is decreased. 
     Additionally, the optimized wake-up module  460  may reduce the standby time of one subscription in slotted mode. In this manner, the optimized wake-up module  460  may reduce the conflicts between dual subscriptions wakeup in Dual SIM Dual Standby (DSDS) devices (or any device containing multiple SIMs). 
     The optimized wake-up module  460  may include one or more wake-up records  462 . Each wake-up record  462  may correspond to a stored sub-slot number  464 , a count  466 , a cell ID  468 , a PN (pseudonoise) code  470  and/or a record ID  472 . The number of wake-up records  462  on the optimized wake-up module  460  may depend on the number of cell IDs  468  and PN codes  470  available to the wireless communication device  404 . 
     Only one wake-up record  462  may be active at a time. The active wake-up record  462  may correspond to the current cell ID  468  and current PN code  470  of the wireless communication device  404 . Table 1 illustrates two wake-up records  462 . 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Record ID 
                 Cell ID 
                 PN Code 
                 Stored Sub-Slot Number 
                 Count 
               
               
                   
               
             
            
               
                 0 
                 Cellid1 
                 PN1 
                 Sub-slot Number 
                 Count1 
               
               
                 1 
                 Cellid1 
                 PN2 
                 Sub-slot Number 
                 Count2 
               
               
                   
               
            
           
         
       
     
     The stored sub-slot number  464  may refer to the sub-slot or frame where a page message was recently decoded. In other words, the stored sub-slot number  464  may refer to the specific sub-slot for which the wireless communication device  404  was required to be in standby mode to detect and decode the page message. The base station  402  may assign and reassign the required sub-slot where the page message is to be received and decoded. Based on the sub-slot assignment by the base station  402 , the wireless communication device  404  may change and/or update the stored sub-slot number  464 . In other words, the new sub-slot number replaces the stored sub-slot number  464   
     In some instances, the wake-up record  462  may have only one stored sub-slot number  464 . This may occur when the stored sub-slot number  464  is the sub-slot number for which the wake-up record  462  is currently counting. In other words, the base station  402  is sending page messages during the same sub-slot number as the stored sub-slot number  464 . For example the base station  402  sends the page message during sub-slot 6 when the stored sub-slot number  464  is sub-slot 6. 
     When the wireless communication device  404  decodes a page message in a sub-slot, the count  466  is saved and/or incremented. If the wireless communication device  404  decodes a page message in a sub-slot that has the same sub-slot number as the stored sub-slot number  464 , the count may be incremented. If the wireless communication device  404  decodes a page message in a sub-slot that has a different sub-slot number than the stored sub-slot number  464 , the stored sub-slot number  464  may be set to the new sub-slot number and the count  466  may be reset (i.e., set to 0). 
     For example, if an empty general page message (GPM)  488  or a direct page message  486  is detected in the third sub-slot, the stored sub-slot number may be set to 3 and the count  466  may be set to 0. If the wireless communication device  404  subsequently (i.e., in the next slot corresponding to the slot cycle index (SCI) assigned to the wireless communication device  404 ) decodes another empty general page message  488  or a direct page message  486  in the third sub-slot, the stored sub-slot number may remain at 3 and the count may be incremented to 1. This process may be repeated as shown in Table 2 below. For example, the wireless communication device may receive two additional page messages, as shown in record ID  472  2 and 3 in Table 2. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Record ID 
                 Cell ID 
                 PN Code 
                 Stored Sub-Slot Number 
                 Count 
               
               
                   
               
             
            
               
                 0 
                 Cellid1 
                 PN1 
                 Sub-slot 3 
                 0 
               
               
                 1 
                 Cellid1 
                 PN1 
                 Sub-slot 3 
                 1 
               
               
                 2 
                 Cellid1 
                 PN1 
                 Sub-slot 3 
                 2 
               
               
                 3 
                 Cellid1 
                 PN1 
                 Sub-slot 3 
                 3 
               
               
                 4 
                 Cellid1 
                 PN2 
                 Sub-slot 4 
                 0 
               
               
                   
               
            
           
         
       
     
     If the wireless communication device  404  subsequently decodes a page message in the fourth sub-slot, the stored sub-slot number  464  may be set to 4 and the count  466  may be reset to 0, as shown record ID  472  4 in Table 2. It should be noted that while multiple records are displaced for sub-slot 3 (e.g., record IDs  472  0-3), a single wake-up record  462  could be employed for sub-slot 3 where only the count  466  changes for each additional page message received at sub-slot 3. Under this latter approach, record ID  472  0 in Table 2 would correlate to sub-slot 3 and record ID  472  1 would correlate to sub-slot 4. 
     In some configurations, when the wireless communication device  404  subsequently decodes a page message in a sub-slot where it has previously counted, but is not currently counting, the count  466  may be either be reset to 0 or the count  466  may continue to be incremented. For example, in Table 2, if the wireless communication device  404  subsequently decodes a page messages in the third sub-slot, record ID  472  5 (not shown) may either reset to 0 or may be incremented to 4. 
     The wireless communication device  404  may also include a consecutive sub-slot threshold  474 . The consecutive sub-slot threshold  474  may be a predefined threshold. In one configuration, the consecutive sub-slot threshold  474  may be configurable (e.g., adjustable or variable). For example, if the consecutive sub-slot threshold  474  is configurable, the base station  102  may change or update the consecutive sub-slot threshold  474  on the wireless communication device  404 . 
     When the count is equal to or greater than the consecutive sub-slot threshold  474 , the optimized wake-up module  460  may set a page message receiving sub-slot  476  to the stored sub-slot number  464 . The page message receiving sub-slot  476  may indicate to the wireless communication device  404  which sub-slot the wireless communication device  404  should begin receiving page messages. Initially, the page message receiving sub-slot  476  may be set to the first sub-slot (e.g., the slot boundary). Whenever the count  466  is reset (e.g., set to 0), the page message receiving sub-slot  476  may also be reset to the first sub-slot. For example, if the page message receiving sub-slot  476  is set to the third sub-slot, the wireless communication device  404  may remain asleep during the first sub-slot and the second sub-slot, but wake up to receive page messages and perform page matching prior to the third sub-slot. 
     Using optimized wake-up may increase the sleep mode time of the wireless communication device  404 . Depending, on the sub-slot in which the page message is transmitted, different increases in sleep mode duration may be achieved. Table 3 below shows the percentage of increase in sleep mode time based on the sub-slot number in which the page message is transmitted. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Sub-slot 
                 Time in 
                 Time in 
                 Sleep Mode Time 
               
               
                 Number in 
                 Standby Mode 
                 Standby Mode 
                 Percentage of 
               
               
                 which the 
                 (if in 
                 (if using 
                 Increase (using 
               
               
                 Page Message 
                 Standby from 
                 optimized 
                 optimized 
               
               
                 is Transmitted 
                 sub-slot 1) 
                 wake-up) 
                 wake-up) 
               
               
                   
               
             
            
               
                 2 
                  40 ms 
                 20 ms 
                 100% 
               
               
                 3 
                  60 ms 
                 20 ms 
                 200% 
               
               
                 4 
                  80 ms 
                 20 ms 
                 300% 
               
               
                 5 
                 100 ms 
                 20 ms 
                 400% 
               
               
                 6 
                 120 ms 
                 20 ms 
                 500% 
               
               
                 7 
                 140 ms 
                 20 ms 
                 600% 
               
               
                   
               
            
           
         
       
     
     Table 3 shows that the optimized wake-up module  460  can reduce the amount of standby time the wireless communication device  404  spends in standby mode monitoring for the page message. Optimized wake-up may be implemented with software changes in 1×Layer 3  and 1×Layer 1 . 
     In addition, in low end chipsets, increases in sleep mode time may be very beneficial. For example, optimized wake-up may be useful in dual SIM dual standby (DSDS). A wireless communication device  404  that uses dual SIM dual standby (DSDS) may be any wireless communication device  404  that is capable of communicating using more than one radio access technology (RAT). For example, the optimized wake-up module  460  may reduce conflicts between CDMA and GSM wake-up. 
     Multiple SIM technology, such as Dual SIM dual standby (DSDS), is a popular feature in China, India, South East Asia, Latin America, and other markets. To be competitive in markets utilizing dual SIM dual standby (DSDS), a wireless communication device  404  may need to have optimal power consumption and lower hardware cost. For example, a wireless communication device  404  that has higher power consumption and a dual receiver may be unable to compete in a dual SIM dual standby (DSDS) market. Thus, reducing the hardware cost and power consumption of a dual SIM dual standby (DSDS) wireless communication device  404  is desirable. 
       FIG. 5  shows a timing diagram of the optimized wake-up mode of a wireless communication device  104  according to some embodiments of the present invention. The timing diagram includes a slot of a paging channel separated into four sub-slots  527   a - d  or frames. The sub-slots  527   a - d  may be divided by sub-slot boundaries  541  with slot boundaries  529 . For simplicity, only one slot boundary  529  and sub-slot boundary  541  is labeled. In some configurations, the sub-slots  527   a - d  may be 20 millisecond (msec) in duration and may combine to from one of the two 80 msec partitioned paging channel slots, as defined under the IS-2000 standard. Additionally, the sub-slot  527   a - d  may correlate to a slot cycle index (SCI). 
     In the timing diagram shown, the page message receiving sub-slot  476  may be set to sub-slot 3 (i.e., the third sub-slot  527   c ). When the page message receiving sub-slot  476  is set to sub-slot 3, the wireless communication device  104  does not wake-up (e.g., is in sleep mode  525   a - b  and does not enter standby mode) to receive page messages and perform page matching until just prior to the third sub-slot  527   c . Thus, the wireless communication device  104  may remain in sleep mode  525  during the first sub-slot  527   a  and the second sub-slot  527   b . Prior to the third sub-slot  527   c , the wireless communication device  104  may wake-up in time to perform warm up procedures  533  and reacquire procedures  535 . Reacquire procedures  535  may include synchronizing with the base station  102 , aligning with the base station  102 , determining which base station  102  is optimal, etc. 
     The wireless communication device  104  may receive  531  page messages during the third sub-slot  527   c . It is assumed for this example that the base station  102  is sending the page message during the third sub-slot  527   c . If the base station  102  does not send the page message in the third sub-slot  527   c , the wireless communication device  104  may remain awake until either the page message is received  531  or the eighth sub-slot (not shown) is completed. If the page message is not included in any of the sub-slots subsequent to the third sub-slot  527   c , the wireless communication device  104  may reset the page message receiving sub-slot  476  to the first sub-slot  527   a , the stored sub-slot number  464  in the wake-up record  462  to the first sub-slot  527   c  and the count in the wake-up record  462  to  0 . In this manner, the wake-up record  462  may be updated. 
     If the wireless communication device  104  receives  531  a page message in the third sub-slot  527   c , the wireless communication device  104  may increment the count  466  in the wake-up record  462 . The wireless communication device  104  may employ decode page message procedures  537 . If the page message is an empty general page message (GPM)  488 , the wireless communication device  104  may enter sleep mode  525   d  immediately (e.g., in the fourth sub-slot  527   d ). If the page message is a direct page message  486 , the wireless communication device  104  may perform access procedures  539   d.    
     If the wireless communication device  104  subsequently receives a page message in the second sub-slot  527   b , the wireless communication device  104  may reset the count  466  in the wake-up record  462 . Additionally, the wireless communication device  104  may create a new wake-up record  462  indicating the stored sub-slot number  464  as the second sub-slot  527   b  rather that the third sub-slot  527   c . This is shown in greater detail below in  FIG. 6 . 
     It should be noted that the timing diagram of  FIG. 5  illustrates the timing for a page message received via the paging channel and not data or bits received on the quick paging channel (QPCH). The wireless communication device  104  described herein monitors the paging cannel, not the QPCH. In other words, the paging message is not received via a quick paging channel. 
     The embodiments of the present invention described herein may work with or without the presence of a QPCH. In the case of a QPCH, the QPCH may fail or miss a page indicator bit indicating a forthcoming paging message. In this case, the wireless communication device  104  will wake-up and monitor for a paging message based on the optimized wake-up module  460 . 
       FIG. 6  shows another timing diagram of the optimized wake-up mode of a wireless communication device  104  according to some embodiments of the present invention. The timing diagram of  FIG. 6  may include slot boundaries  629 , sub-slot boundaries  641 , sub-slots  627   a - d , warm-up procedures  633 , reacquire procedures  635  and decode page message procedures  637  similar to corresponding elements  529 ,  541 ,  527   a - d ,  533 ,  535  and  537  described above in connection with  FIG. 5 . The sub-slot  627   a - d  may correlate to a slot cycle index (SCI). 
     If the wireless communication device  104  subsequently receives a page message in the second sub-slot  527   b , the wireless communication device  104  may reset the count  466  in the wake-up record  462 . Additionally, the wireless communication device  104  may create a new wake-up record  462  indicating the stored sub-slot number  464  as the second sub-slot  527   b  rather that the third sub-slot  527   c.    
     In the timing diagram shown, the page message receiving sub-slot  476  may be set to sub-slot 2 (i.e., the second sub-slot  627   b ) when a page message is received in the second sub-slot  627   b . If the page message receiving sub-slot  476  was set to a sub-slot  627  other than the second sub-slot  627   b , the wireless communication device  104  may change the page message receiving sub-slot  476  to the second sub-slot  627   b.    
     However, in some instances, the wireless communication device  104  may not change the page message receiving sub-slot  476  to the second sub-slot  627   b  until the consecutive sub-slot threshold  474  has been met or exceeded. For example, the wireless communication device  104  may receive four subsequent page messages in the second sub-slot  627   b , making the count  466  in the wake-up record  462  for that record ID  472  equal to 4. The wireless communication device  104  may then receive a single page message in the fourth sub-slot  627   d . If the consecutive sub-slot threshold  474  is set to be greater than or equal to 3, the wireless communication device  104  may not change the page message receiving sub-slot  476 . 
     Then if the wireless communication device  104  again receives a subsequent page message in the second sub-slot  627   b , the count  466  for the original record may be incremented and the page message receiving sub-slot  476  may remain the second sub-slot  627   b . In this manner, if the base station  102  sends a limited number of page messages in different sub-slots  627   a - d , the wireless communication device  104  may still perform an optimized wake-up procedure when the base station  102  again sends page messages to the sub-slot  627   a - d  that correlates to the stored sub-slot number  464  in the wake-up record  462 . Further, periodic page messages received at different sub-slots  627   a - d  due to errors, reflections, etc., will have a minimal effect on the optimized wake-up procedure. 
     Returning to  FIG. 6 , when the page message receiving sub-slot  476  is set to the second sub-slot  627   b , the wireless communication device  104  does not wake-up (e.g., is in sleep mode  625   a ) to receive page messages and perform page matching until the second sub-slot  627   b . Thus, the wireless communication device  104  may remain in sleep mode  625   a  during the first sub-slot  627   a . Prior to the second sub-slot  627   b , the wireless communication device  104  may wake-up in time to perform warm-up procedures  633  and reacquire procedures  635 . This optimized wake-up procedure allows the wireless communication device  104  to remain in sleep mode  625  for a longer period of time. 
     The wireless communication device  104  may receive a page message  631  during the second sub-slot  627   b . It is assumed for this example that the base station  102  is sending the page message during the second sub-slot  627   b . If the wireless communication device  104  receives a page message  631  in the second sub-slot  627   b , the wireless communication device  104  may increment the count  466  in the wake-up record  462 . The wireless communication device  104  may also employ decode page message procedures  637 . If the page message is an empty general page message (GPM)  488 , the wireless communication device  104  may enter sleep mode  625   c  immediately (e.g., in the third sub-slot  627   c ) and continue in sleep mode  625   d  in the fourth sub-slot  627   d.    
     If the page message is a direct page message  486 , the wireless communication device  104  may perform access procedures  639   c  in the third sub-slot  627   c  and, if necessary, perform access procedures  639   d  in the fourth sub-slot  627   d . If the wireless communication device  104  has completed the access procedures  639   c  in the third sub-slot  627   c , the wireless communication device  104  may enter sleep mode  625   d  in the fourth sub-slot  627   d . Overall, the optimized wake-up procedures as described in the embodiments of the present invention allow the wireless communication device  104  to remain in standby mode for less time, which leads to an increase in power savings. 
       FIG. 7  shows a flow diagram illustrating a method  700  for optimizing wake-up according to some embodiments of the present invention. The method  700  may be performed by a wireless communication device  104 . The wireless communication device  104  may receive  702  page messages at a page message receiving sub-slot  476 . As discussed above, the page message receiving sub-slot  476  may be one of the sub-slots (e.g., sub-slots  527   a - d ) corresponding to the slot cycle index (SCI) assigned to the wireless communication device  104 . The wireless communication device  104  may detect  704  an empty general page message (GPM)  488  and/or direct page message  486  in a sub-slot  527   a - d.    
     The sub-slot  527   a - d  may correspond to a sub-slot number. For example, the second sub-slot  527   b  may correspond to sub-slot number 2. The wireless communication device  104  may then determine  706  whether the sub-slot number matches the stored sub-slot number  464  in the active wake-up record  462 . 
     If the sub-slot number in which the page message was detected  704  is not the stored sub-slot number  464 , the wireless communication device  104  may reset  708  the page message receiving sub-slot  476  to the first sub-slot (e.g., first sub-slot  527   a ). The wireless communication device  104  may also reset  710  the count  466  for the wake-up record  462  to 0. The wireless communication device  104  may set  712  the sub-slot number as the stored sub-slot number  464 . Performing the steps of resetting  708  the page message, resetting  710  the count  466  and/or setting  712  the sub-slot number  464  may update the wake-up record  462 . 
     The wireless communication device  104  may determine  720  if the received page message is an empty general page message (GPM)  488  or a direct page message  486 . If the received page message is an empty general page message (GPM)  488 , the wireless communication device  104  may enter  722  sleep mode. In this case, the wireless communication device  104  may enter sleep mode until the next sub-slot defined by the page message receiving sub-slot  476 . The wireless communication device  104  may than begin the method  700  over again. 
     If the received page message is a direct page message  486 , the wireless communication device  104  may perform  724  access procedures. Once access procedures have been performed  724 , the wireless communication device  104  may enter  722  sleep mode. The wireless communication device  104  may than begin the method  700  over again. 
     If sub-slot number in which the page message was detected  704  is the stored sub-slot number  464 , the wireless communication device  104  may increment  714  the count  466  for the wake-up record  462 . In this manner, the wake-up record  462  is updated. The wireless communication device  104  may then determine  716  whether the count  466  is greater than or equal to a consecutive sub-slot threshold  474 . 
     If the count  466  is greater than or equal to the consecutive sub-slot threshold  474 , the wireless communication device  104  may adjust  718  the page message receiving sub-slot  476  to the stored sub-slot number  464 , which updates the wake-up record  462 . Based on the determination  720 , the wireless communication device  104  either enters  722  sleep mode or performs  724  access procedures, as described above. The wireless communication device  104  may than begin the method  700  over again. 
     If the count  466  is not greater than or equal to the consecutive sub-slot threshold  474 , the wireless communication device  104  may make no adjustments to the page message receiving sub-slot  476 . The wireless communication device  104  may then determine  720  if the received page message is an empty general page message (GPM)  488  or a direct page message  486 . Based on the determination  720 , the wireless communication device  104  either enters  722  sleep mode or performs  724  access procedures, as described above. The wireless communication device  104  may than begin the method  700  over again. 
       FIG. 8  shows a flow diagram illustrating a method  800  for optimized wake-up during a switch of pseudonoise (PN) codes  470  according to some embodiments of the present invention. The method  800  may be performed by a wireless communication device  104 . The wireless communication device  104  may have an established wake-up record  462  for a first PN code. The wireless communication device  104  move  802  from the first PN code to a second PN code of the home system. The wireless communication device  104  may store  804  the wake-up record  462  for the first PN code. For example, the wake-up record  462  for the first PN code may be stored  804  for future use. 
     The wireless communication device  104  may determine  806  whether the second PN code has a corresponding wake-up record  462 . In other words, the wireless communication device  104  may determine whether a wake-up record  462  for the second PN code is established. If a wake-up record  462  for the second PN code is established, the wireless communication device  104  may use  816  the wake-up record  462  for the second PN code. In this manner, the wireless communication device  104  may switch from the wake-up record  462  for the first PN code to the wake-up record  462  for the second PN code. 
     If a wake-up record  462  for the second PN code is not established, the wireless communication device  104  may generate  808  a new wake-up record  462  for the second PN code. The wireless communication device  104  may set  810  the stored sub-slot number  464  for the wake-up counter for the second PN code to the first sub-slot (e.g., first sub-slot  527   a ). 
     The wireless communication device  104  may initialize  812  the page message receiving sub-slot  476  to the first sub-slot (e.g., first sub-slot  527   a ). The wireless communication device  104  may initialize  814  the count  466  for the wake-up record  462  for the second PN code to 0. 
       FIG. 9  shows certain components that may be included within a wireless communication device  904  according to some embodiments of the present invention. The wireless communication device  904  may be an access terminal, a mobile station, a user equipment (UE), etc. The wireless communication device  904  includes a processor  903 . For example the wireless communication device  904  may be the wireless communication device  104  of  FIG. 1  and/or the wireless communication device  404  of  FIG. 4 . 
     The processor  903  may be a general purpose single- or multi-chip microprocessor (e.g., an ARM), a special purpose microprocessor (e.g., a digital signal processor (DSP)), a microcontroller, a programmable gate array, etc. The processor  903  may be referred to as a central processing unit (CPU). Although just a single processor  903  is shown in the wireless communication device  904  of  FIG. 9 , in an alternative configuration, a combination of processors (e.g., an ARM and DSP) could be used. 
     The wireless communication device  904  also includes memory  905 . The memory  905  may be any electronic component capable of storing electronic information. The memory  905  may be embodied as random access memory (RAM), read-only memory (ROM), magnetic disk storage media, optical storage media, flash memory devices in RAM, on-board memory included with the processor, EPROM memory, EEPROM memory, registers and so forth, including combinations thereof. 
     Data  907   a  and instructions  909   a  may be stored in the memory  905 . The instructions  909   a  may be executable by the processor  903  to implement the methods disclosed herein. Executing the instructions  909   a  may involve the use of the data  907   a  that is stored in the memory  905 . When the processor  903  executes the instructions  909 , various portions of the instructions  909   b  may be loaded onto the processor  903 , and various pieces of data  907   b  may be loaded onto the processor  903 . 
     The wireless communication device  904  may also include a transmitter  911  and a receiver  913  to allow transmission and reception of signals to and from the wireless communication device  904  via an antenna  917 . The transmitter  911  and receiver  913  may be collectively referred to as a transceiver  915 . The wireless communication device  904  may also include (not shown) multiple transmitters, multiple antennas, multiple receivers and/or multiple transceivers. 
     The wireless communication device  904  may include a digital signal processor (DSP)  921 . The wireless communication device  904  may also include a communications interface  923 . The communications interface  923  may allow a user to interact with the wireless communication device  904 . 
     The various components of the wireless communication device  904  may be coupled together by one or more buses, which may include a power bus, a control signal bus, a status signal bus, a data bus, etc. For the sake of clarity, the various buses are illustrated in  FIG. 9  as a bus system  919 . 
     The techniques described herein may be used for various communication systems, including communication systems that are based on an orthogonal multiplexing scheme. Examples of such communication systems include Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems and so forth. An OFDMA system utilizes orthogonal frequency division multiplexing (OFDM), which is a modulation technique that partitions the overall system bandwidth into multiple orthogonal sub-carriers. These sub-carriers may also be called tones, bins, etc. With OFDM, each sub-carrier may be independently modulated with data. An SC-FDMA system may utilize interleaved FDMA (IFDMA) to transmit on sub-carriers that are distributed across the system bandwidth, localized FDMA (LFDMA) to transmit on a block of adjacent sub-carriers, or enhanced FDMA (EFDMA) to transmit on multiple blocks of adjacent sub-carriers. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDMA. 
     The term “determining” encompasses a wide variety of actions and, therefore, “determining” can include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” can include resolving, selecting, choosing, establishing and the like. 
     The phrase “based on” does not mean “based only on,” unless expressly specified otherwise. In other words, the phrase “based on” describes both “based only on” and “based at least on.” 
     The term “processor” should be interpreted broadly to encompass a general purpose processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a controller, a microcontroller, a state machine, and so forth. Under some circumstances, a “processor” may refer to an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), etc. The term “processor” may refer to a combination of processing devices, e.g., a combination of a digital signal processor (DSP) and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor (DSP) core, or any other such configuration. 
     The term “memory” should be interpreted broadly to encompass any electronic component capable of storing electronic information. The term memory may refer to various types of processor-readable media such as random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable PROM (EEPROM), flash memory, magnetic or optical data storage, registers, etc. Memory is said to be in electronic communication with a processor if the processor can read information from and/or write information to the memory. Memory that is integral to a processor is in electronic communication with the processor. 
     The terms “instructions” and “code” should be interpreted broadly to include any type of computer-readable statement(s). For example, the terms “instructions” and “code” may refer to one or more programs, routines, sub-routines, functions, procedures, etc. “Instructions” and “code” may comprise a single computer-readable statement or many computer-readable statements. 
     The functions described herein may be implemented in software or firmware being executed by hardware. The functions may be stored as one or more instructions on a computer-readable medium. The terms “computer-readable medium” or “computer-program product” refers to any tangible storage medium that can be accessed by a computer or a processor. By way of example, and not limitation, a computer-readable medium may 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 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), floppy disk and Blu-Ray® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. It should be noted that a computer-readable medium may be tangible and non-transitory. The term “computer-program product” refers to a computing device or processor in combination with code or instructions (e.g., a “program”) that may be executed, processed or computed by the computing device or processor. As used herein, the term “code” may refer to software, instructions, code or data that is/are executable by a computing device or processor. 
     Software or instructions may also be transmitted over a transmission medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of transmission medium. 
     The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is required for proper operation of the method that is being described, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. 
     Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein, such as those illustrated by  FIG. 7  and  FIG. 8 , can be downloaded and/or otherwise obtained by a device. For example, a device may be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via a storage means (e.g., random access memory (RAM), read-only memory (ROM), a physical storage medium such as a compact disc (CD) or floppy disk, etc.), such that a device may obtain the various methods upon coupling or providing the storage means to the device. 
     It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the systems, methods, and apparatus described herein without departing from the scope of the claims.