Abstract:
Systems and methodologies are described that facilitate evaluating and utilizing timing updates in a wireless communications network. A base station can transmit timing adjustment commands to mobile devices as needed as opposed to a periodic timing update where timing adjustment commands are always sent within a certain period. However, the mobile devices need to stay awake to monitor the timing adjustment message resulting in high power consumption. On the other hand with periodic update, the mobile devices can wake up to check whether there is a timing adjustment for itself and, if not, return to a sleep mode. With the proposed method, a mobile device can sleep for a period of time to check for timing adjustment commands upon waking. Thus, both the mobile power consumption and downlink signaling overhead are reduced.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent application Ser. No. 60/895,695 entitled “UL TIMING CONTROL” which was filed Mar. 19, 2007. The entirety of the aforementioned application is herein incorporated by reference. 
    
    
     BACKGROUND 
     I. Field 
     The following description relates generally to wireless communications, and more particularly to uplink timing control. 
     II. Background 
     Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, . . . ). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), etc. 
     Generally, wireless multiple-access communication systems may simultaneously support communication for multiple mobile devices. Each mobile device may communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations. Further, communications between mobile devices and base stations may be established via single-input single-output (SISO) systems, multiple-input single-output (MISO) systems, multiple-input multiple-output (MIMO) systems, and so forth. In addition, mobile devices can communicate with other mobile devices (and/or base stations with other base stations) in peer-to-peer wireless network configurations. 
     MIMO systems commonly employ multiple (N T ) transmit antennas and multiple (N R ) receive antennas for data transmission. A MIMO channel formed by the N T  transmit and N R  receive antennas may be decomposed into N S  independent channels, which may be referred to as spatial channels, where N S ≦{N T ,N R }. Each of the N S  independent channels corresponds to a dimension. Moreover, MIMO systems may provide improved performance (e.g., increased spectral efficiency, higher throughout and/or greater reliability) if the additional dimensionalities created by the multiple transmit and received antennas are utilized. 
     MIMO systems may support various depleting techniques to divide forward and reverse link communications over a common physical medium. For instance, frequency division duplex (FDD) systems may utilize disparate frequency regions for forward and reverse link communications. Further, in time division duplex (TDD) systems, forward and reverse link communications may employ a common frequency region. However, conventional techniques may provide limited or no feedback related to channel information. 
     SUMMARY 
     The following presents a simplified summary of one or more embodiments in order to provide a basic understanding of such embodiments. This summary is not an extensive overview of all contemplated embodiments, and is intended to neither identify key or critical elements of all embodiments nor delineate the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later. 
     According to ail aspect, a method for acquiring a time adjustment is described herein. The method can comprise entering a sleep mode. In addition, the method can include waking from the sleep mode after a predetermined period of time passes. Moreover, the method can comprise determining whether a timing adjustment command issues. The method can also comprise adjusting uplink timing based at least in part on the issued timing adjustment command and reentering the sleep mode. 
     Another aspect relates to a wireless communications apparatus that can comprise a memory retains instructions related to sleeping until a timer expires, waking after the timer expires, assessing if a timing adjustment command issues and adjusting uplink timing based at least in part on the issued command. The wireless communications apparatus call also include a processor coupled to the memory and configured to execute the instructions retained in the memory. 
     Yet another aspect relates to a wireless communications apparatus that facilitates conserving power when acquiring a time adjustment. The apparatus can include means for entering a sleep mode. The apparatus can further comprise means for waking from the sleep mode after a predetermined period of time passes. In addition, the wireless communications apparatus can include means for determining whether a timing adjustment command issues. Moreover, the apparatus can comprise means for adjusting uplink timing based at least in part on the issued timing adjustment command and means for reentering the sleep mode. 
     Still another aspect relates to a machine-readable medium having stored thereon machine-executable instructions for entering a sleep mode and waking from the sleep mode after a predetermined period of time passes. In addition, the machine-readable medium can further comprise instructions for determining whether a timing adjustment command issues. Moreover, the machine-readable medium can include instructions for adjusting uplink timing based at least in part on the issued timing adjustment command and reentering the sleep mode. 
     According to another aspect an apparatus can comprise an integrated circuit in a wireless communication system. The integrated circuit can be configured to place the apparatus in a sleep mode. The integrated circuit can further be configured to wake the apparatus from the sleep mode after a predetermined period of time passes. In addition, the integrated circuit can be configured to determine whether a timing adjustment command issues. Moreover, the integrated circuit can, be configured to adjust uplink timing based at least in part on the issued timing adjustment command. 
     According to yet another aspect, a method for updating timing is described herein. The method can comprise receiving a transmission from at least one waking mobile device that provides uplink information. The method can further include determining whether at least one waking mobile device requires a timing update based upon the received transmission. In addition, the method can comprise evaluating a timing adjustment for the at least one waking mobile device. The method can also include issuing a timing adjustment command to the at least one waking mobile device. 
     Another aspect described herein relates to a wireless communications apparatus that can include a memory. The memory can retain instructions related to receiving a transmission from at least one waking mobile device that provides uplink information, determining whether at least one waking mobile device requires a timing update based upon the received transmission, evaluating a timing adjustment for the at least one waking mobile device; and issuing a timing adjustment command to the at least one waking mobile device. In addition, the wireless communications apparatus can include a processor coupled to the memory and configured to execute the instructions retained in the memory. 
     Yet another aspect relates to a wireless communications apparatus that facilitates updating timing with reduced overhead. The apparatus can comprise means for receiving a transmission from at least one waking mobile device that provides uplink information. The apparatus can also comprise means for determining whether at least one waking mobile device requires a timing update based upon the received transmission. In addition, the apparatus can include means for evaluating a timing adjustment for the at least one waking mobile device. Moreover, the apparatus can also include means for issuing a timing adjustment command to the at least one waking mobile device. 
     Still another aspect relates to a machine-readable medium having stored thereon machine-executable instructions for receiving a transmission from at least one waking mobile device that provides uplink information. The machine-readable medium can further include instructions related to determining whether at least one waking mobile device requires a timing update based upon the received transmission. In addition, the machine-readable medium can comprise instructions for evaluating a timing adjustment for the at least one waking mobile device. The machine-readable medium can also include instructions for issuing a timing adjustment command to the at least one waking mobile device. 
     A further aspect describe herein relates to an apparatus in a wireless communication, system comprising an integrated circuit. The integrated circuit can be configured, to receive a transmission from at least one waking mobile device that provides uplink information. The integrated circuit can be further configured to determine whether at least one waking mobile device requires a timing update based upon the received transmission. In addition, the integrated circuit can be configured to evaluate a timing adjustment for the at least one waking mobile device and to issue a timing adjustment command to the at least one waking mobile device. 
     To the accomplishment of the foregoing and related ends, the one or more embodiments comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the one or more embodiments. These aspects are indicative, however, of but a few of the various ways in which the principles of various embodiments may be employed and the described embodiments are intended to include all such aspects and their equivalents. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of a wireless communication system in accordance with various aspects set forth herein. 
         FIG. 2  is an illustration of an example communications apparatus for employment within a wireless communications environment. 
         FIG. 3  is an illustration of an example wireless communications system that facilitates uplink timing control. 
         FIG. 4  is at illustration of example sector in accordance with an aspect of the subject disclosure. 
         FIG. 5  is an illustration of an example methodology that facilitates providing timing updates in a wireless communications network. 
         FIG. 6  is an illustration of an example methodology that facilitates conserving power while acquiring timing updates. 
         FIG. 7  is an illustration of an example mobile device that facilitates acquiring and utilizing timing adjustments. 
         FIG. 8  is an illustration of an example system that facilitates evaluating, transmitting and receiving timing updates for uplink channels. 
         FIG. 9  is an illustration of an example wireless network environment that can be employed in conjunction with the various systems and methods described herein. 
         FIG. 10  is an illustration of an example system that utilizes timing adjustments to control uplink timing. 
         FIG. 11  is an illustration of an example system that evaluates and transmits timing adjustments. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) can be practiced without these specific, details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or snore embodiments. 
     As used in this application, the terms “component,” “module,” “system,” and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component can be, hut is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components can communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the Internet with other systems by way of the signal). 
     Furthermore, various embodiments are described herein in connection with a mobile device. A mobile device can also be called a system, subscriber unit, subscriber station, mobile station, mobile, remote station, remote terminal, access terminal, user terminal, terminal, wireless communication device, user agent, user device, or user equipment (UE). A mobile device can be a cellular telephone, a cordless telephone, a Session Initiation Protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device having wireless connection capability, computing device, or other processing device connected to a wireless modem. Moreover, various embodiments are described herein in connection with a base station. A base station can be utilized for communicating with mobile device(s) and can also be referred to as an access point, Node B, or some other terminology. 
     Moreover, various aspects or features described herein can be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques. The term “article of manufacture” as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. For example, computer-readable media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips, etc.), optical disks (e.g., compact disk (CD), digital versatile disk (DVD), etc.) smart cards, and flash memory devices (e.g., EPROM, card, stick, key drive, etc.). Additionally, various storage media described herein can represent one or more devices and/or other machine-readable media for storing information. The term “machine-readable medium” can include, without being limited to wireless channels and various other media capable of storing, containing, and/or carrying instruction(s) and/or data. 
     Referring now to  FIG. 1 , a wireless communication system  100  is illustrated in accordance with various embodiments presented herein. System  100  comprises a base station  102  that can include multiple antenna groups. For example, one antenna group can include antennas  104  and  106 , another group can comprise antennas  108  and  110 , and an additional group can include antennas  112  and  114 . Two antennas are illustrated for each antenna group; however, more or fewer antennas can be utilized for each group. Base station  102  can additionally include a transmitter chain and a receiver chain, each of which can in turn comprise a plurality of components associated with signal transmission and reception (e.g., processors, modulators, multiplexers, demodulators, demultiplexers, antennas, etc.), as will be appreciated by one skilled in the art. 
     Base station,  102  can communicate with one or more mobile devices such as mobile device  116  and mobile device  122 ; however, it is to be appreciated that base station  102  can communicate with substantially any number of mobile devices similar to mobile devices  116  and  122 . Mobile devices  116  and  122  can be, for example, cellular phones, smart phones, laptops, handheld communication devices, handheld computing devices, satellite radios, global positioning systems, PDAs, and/or any other suitable device for communicating over wireless communication system  100 . As depicted, mobile device  116  is in communication with antennas  112  and  114 , where antennas  112  and  114  transmit information to mobile device  116  over a forward link  118  and receive information from mobile device  116  over a reverse link  120 . Moreover, mobile device  122  is in communication with antennas  104  and  106 , where antennas  104  and  106  transmit information to mobile device  122  over a forward link  124  and receive information from mobile device  122  over a reverse link  126 . In a frequency division duplex (FDD) system, forward link  118  can utilize a different frequency band than that used by reverse link  120 , and forward link  124  can employ a different frequency band than that employed by reverse link  126 , for example. Further, in a time, division duplex (TDD) system, forward link  118  and reverse link  120  can utilize a common frequency band and forward link  124  and reverse link  126  can utilize a common frequency band. 
     Each group of antennas and/or the area in which they are designated to communicate can be referred to as a sector of base station  102 . For example, antenna groups can be designed to communicate to mobile devices in a sector of the areas covered by base station  102 . In communication over forward links  118  and  124 , the transmitting antennas of base station  102  can utilize beamforming to improve signal-to-noise ratio of forward links  118  and  124  for mobile devices  116  and  122 . Also, while base station  102  utilizes beamforming to transmit to mobile devices  116  and  122  scattered randomly through an associated coverage, mobile devices in neighboring cells can be subject to less interference as compared to a base station transmitting through a single antenna to all its mobile devices. Moreover, mobile devices  116  and  122  can communicate directly with one another using a peer-to-peer or ad hoc technology as depicted. 
     Turning to  FIG. 2 , illustrated is a communications apparatus  200  for employment within a wireless communications environment. The communications apparatus  200  can be a base station or a portion thereof, a mobile device or a portion thereof, or substantially any communications apparatus that receives data transmitted in a wireless communications environment. In communications systems, communication timing between transmitters and receivers can require adjustment. Thus, the communications apparatus,  200  employ components described below to maintain timing synchronization. The communications apparatus  200  can include a sleep timer  202  that can maintains the communications apparatus  200  in a sleep mode for a predetermined period of time, a timing adjustment receiver  204  that can determine if a timing adjustment command has issued, and a timing adjuster  206  that can execute the timing adjustment command, if it issues, to update communication timing of the communications apparatus  200 . The communications device  200  can receive adjustment commands and adjust timing accordingly without continuously monitoring a channel for the commands. Thus, the communications device  200  can conserver power. 
     According to an example, the communications apparatus  200  can require a timing update. This can occur, for example, as the communications apparatus  200  travels within a communication sector or cell, as another device in communication with the communications apparatus  200  traverse a sector, as propagation conditions change, etc. The communications apparatus  200  can enter a sleep mode that is monitored by the sleep timer  202 . The sleep timer  202  holds the communications apparatus  200  in the sleep mode until a predetermined time passes. Pursuant to all illustration, the sleep timer  202  can maintain a timer mechanism that expires after the predetermined time elapses. According to an aspect, the timer mechanism can initiate (e.g., start the clock) when the communications apparatus  200  enters the sleep mode. In one embodiment, the predetermined period of time can be on the order of seconds. Upon expiration of the sleep timer  202 , the communications apparatus wakes. 
     Upon waking, the timing adjustment receiver  204  checks if a timing adjustment command has been issued. For instance, the timing adjustment receiver  204  can read a downlink physical channel to determine if the timing adjustment command has been transmitted. If the timing adjustment receiver  204  ascertains that the timing adjustment command has not issued, the sleep timer  202  can reinitiated and place the communications apparatus  200  back into the sleep mode for another period defined by the predetermined time. If the timing adjustment receiver  204  discovers the timing adjustment command, the command can be forward to the timing adjuster  206 . The timing adjuster  206  can adjust timing of a communications link based upon the timing adjustment command. For example, the timing adjuster  206  can update uplink timing of a mobile device. Following adjustment, the communications device  200  can re-enter the sleep mode or proceed with other data transmissions. 
     Moreover, although not shown, it is to be appreciated that communications apparatus  200  can include memory that retains instructions with respect to maintaining a sleep timer, checking for timing adjustment commands, receiving-timing adjustment commands, making timing adjustments based upon timing adjustment commands, and the like. Further, communications apparatus  200  can include a processor that may be utilized in connection with executing instructions (e.g., instructions retained within memory, instructions obtained from a disparate source. 
     Now referring to  FIG. 3 , illustrated is a wireless communications system  300  that can provide timing control between communicative parties while reducing transmission overhead and conserving power. The system  300  includes a base station  302  that communicates with a mobile device  304  (and/or any number of disparate mobile devices (not shown)). Base station  302  can transmit information to mobile device  304  over a forward link channel; further base station  302  can receive information from mobile device  304  over a reverse link channel. Moreover, system  300  can be a MIMO system. Additionally, the system  300  can operate in an OFDMA wireless network a 3GPP LTE wireless network, etc. Also, the components and functionalities shown and described below in the base station  302  can be present in the mobile device  304  as well and vice versa, in one example; the configuration depicted excludes these components for ease of explanation. 
     Base station  302  includes a timing adjustment determiner  306  that can determine if mobile device  304  requires a timing update, a timing adjustment evaluator  308  that can ascertain a timing update amount needed and a timing adjustment transmitter  310  that can issue a timing adjustment command. Mobile device  304  includes a sleep timer  312  that can maintains the mobile device  304  in a sleep mode for a predetermined period of time, a timing adjustment receiver  318  that can determine if a timing adjustment command has issued, for example, by base station  302  and a timing adjuster  320  that can execute the timing adjustment command, if it issues, to update uplink timing of the mobile device  304 . Additionally, the mobile device  304  can include a period configurer  312  that can select a period of time to be employed by the sleep timer  312  and an uplink signaler  316  that can transmit a signal to the base station  302  on an uplink channel. 
     According to an example, the base station  302  can maintain synchronization with mobile device  304  and other mobile devices (not shown). In evolved UMTS terrestrial radio access (E-UTRA), transmission among mobile devices such as mobile device  304  or transmission between the mobile device  304  and base station  302  require alignment in time. Alignment in time facilitates maintaining orthogonality between mobile devices and reduces interference. Mobile devices, such as mobile device  304 , can move about within a cell or sector serviced by the base station  302 . Changes in distances between the mobile device  304  and the base station  302  can require an update in uplink timing of mobile device  304  to maintain orthogonality. Pursuant to an illustration, a mobile device moving toward or away from a base station at 350 kilometers per hour can create a change in uplink timing synchronization at a rate of 0.6 microseconds per second. In addition to pure distance changes, propagation conditions can change between a mobile device and base station due to relative movement. 
     Typically, a base station can employ a per-need mechanism or a periodic mechanism to maintain synchronization. With the per-need mechanism, the base station transmits timing adjustment to mobile devices when the base station determines an adjustment is required. With the periodic mechanism, the base station periodically sends adjustment to all active mobile devices. Active mobile devices include mobile devices actively sending data. It is to be appreciated that active mobile devices can also be mobile devices that are not quite active (e.g., sleeping or otherwise not sending data but retaining access to the system). 
     The mobile device  304  can enter a sleep mode that is monitored by the sleep timer  312 . The sleep timer  312  holds the mobile device in the sleep mode until a predetermined time passes. Pursuant to an illustration, the sleep timer  312  can maintain a timer mechanism that expires after the predetermined time elapses. According to an aspect, the timer mechanism can initiate (e.g., start the clock) when the mobile device enters the sleep mode. The period configurer  314  can select the predetermined time employed to configure the sleep timer  312 . According to one aspect, the period configurer  314  can select a period that is shorter than a period utilized by a base station in conventional periodic update mechanisms. The selected period or predetermined time is utilized by the sleep timer  312  to hold the mobile device  304  in the sleep mode for the duration of the selected period. 
     Upon waking, the uplink signaler  316  can transmit a signal to the base station  302 . In one embodiment, the signal can include uplink information. The timing adjustment determiner  306  can determine if the mobile device  304  requires a timing update based upon the signal sent by the uplink signal  316 . Pursuant to an illustration, the timing adjustment determiner  306  can measure a difference between local timing of the base station  302  and timing received in the signal. If a sufficient difference is discovered by the timing adjustment determiner  306 , the timing adjustment evaluator  308  can ascertain an appropriate update value. According to an aspect, the timing adjustment evaluator  308  can be any value required to synchronize the timing received in the signal to the local timing of the base station  302 . The timing adjustment transmitter  310  prepares a timing adjustment command based upon the value evaluated by the timing adjustment evaluator  310 . The timing adjustment transmitter  310  can send the timing adjustment command to the mobile device  304 . For example, the timing adjustment transmitter  310  can send the command on the FPACH channel. 
     The timing adjustment receiver  318  checks if the timing adjustment command has been issued. For instance, the timing adjustment receiver  318  can read the downlink physical channel to determine if the timing adjustment command has been transmitted by the base station  302 . If the timing adjustment receiver  318  ascertains that the timing adjustment command has not issued, the sleep timer  312  can reinitiated and place the mobile device  304  back into the sleep mode for another period defined by the predetermined time. If the timing adjustment receiver  318  discovers the timing adjustment command, the command can be forward to the timing adjuster  320 . The timing adjuster  320  can adjust timing of the uplink based upon the timing adjustment command. According to one aspect, the mobile device  304  can re-enter the sleep mode or proceed with other data transmission following the timing update. 
     It is to be appreciated that the uplink signaler  316  can transmit an uplink signal with uplink information at any time other than upon waking so long as such signal is sent at least once within the predetermined time period established by the period configurer  314 . For example, the uplink signaler  316  can temporarily awaken the mobile device  304  during the middle of the timer to transmit the information. This enables the base station  302  additional time to determine if an update if necessary. In additional, the uplink signaler  316  can transmit the signal prior to entering the sleep mode. 
     Now referring to  FIG. 4 , an example wireless communications system  400  is illustrated according to one or more aspects of the subject disclosure. The system  400  can comprise an access point or base station  402  that receives, transmits, repeats, etc., wireless communication signals to other base stations (not shown) or to one or more terminals such as terminals  406  and  408 . The base station  402  can comprise multiple transmitter chains and receiver chains, e.g., one for each transmit and receive antenna, each of which can in turn comprise a plurality of components associated with signal transmission and reception (e.g., processors, modulators, multiplexers, demodulators, demultiplexers, antennas, etc.). The mobile devices  406  and  408  can be, for example, cellular phones, smart phones, laptops, handheld communication devices, handheld computing devices, satellite radios, global positioning systems, PDAs, and/or any other suitable device for communicating over wireless system  400 . In addition, the mobile devices  406  and  408  can comprise one or more transmitter chains and a receiver chains, such as used for a multiple input multiple output (MIMO) system. Each transmitter and receiver chain can comprise a plurality of components associated with signal transmission and reception (e.g., processors, modulators, multiplexers, demodulators, demultiplexers, antennas, etc.), as will be appreciated by one skilled in the art. 
     As illustrated in  FIG. 4 , the base station  402  provides communication coverage for a particular geographic area  404 . The term “cell” can refer to a base station and/or its coverage area, depending on context. To improve system capacity, an access point coverage area can be partitioned into multiple smaller areas. Each smaller area is served by a respective base transceiver subsystem (BTS). The term “sector” can refer to a BTS and/or its coverage area depending upon context. For a sectorized cell, the base transceiver subsystem for all sectors of the cell is typically co-located within the access point for the cell. 
     According to an example, a mobile device, such as mobile devices  406  and  408 , can detect the cell or sector that covers the geographic area  404  served by the base station  402 . The mobile device acquires timing and synchronization of the base station  402  via a synchronization channel (SCII). Subsequently, the mobile device can access and demodulate a broadcast channel (BCH) to acquire system information. Pursuant to an illustration, system information can include a set of parameters that define how the mobile devices should access and interact with the system  400 . The mobile device can transmit an access probe on a random access channel (RACH). The base station  402  can measure the difference between local reference timing and timing received on the uplink channel of the access problem sent by the mobile device. The base station  402  can transmit an access grant message to the mobile device on a downlink or forward link channel after successfully detecting the access probe. The access grant message can convey uplink resource assignment and/or uplink timing adjustment to the mobile device. 
     After the initial timing adjustment, mobile devices can requires further updates to maintain synchronization. In E-UTRA, uplink transmission among mobile devices should be aligned to maintain orthogonality between the mobile devices. Pursuant to the illustration in  FIG. 4 , the mobile device  406  can be a mobile device that is not moving relative to the base station  402 , a mobile device moving a small degree in terms of distance and/or a mobile device that is traveling at a low speed relative to the base station  402 . In addition, the mobile device  408  can be a moving mobile device that is frequently moving relative to the base station  402  and/or a mobile device that is traveling at a high speed. The base station  402  can employ at least one of a per-need update mechanism or a periodic update mechanism to update timing of the mobile devices  406  and  408 . The per-need update mechanisms reduces overhead by only sending timing adjustments to mobile devices when the base station  402  determines the mobile devices require timing updates. However, the mobile devices  406  and  408  typically need to be awake and monitoring the forward link channels for timing adjustments substantially all the time in order to receive messages containing timing updates. Thus, the mobile device  406  and  408  consume greater power with per-need update mechanisms. 
     The periodic update mechanisms can reduce power consumption on the part of mobile devices  406  and  408  at the cost of increased overhead. The base station  402  can transmit timing updates to all mobile devices once every period. However, to be effective, the period is defined by high speed mobile device such as mobile device  408 . The mobile device  408  requires more frequent timing updates than mobile device  406 . However, the base station  402  transmits updates to the mobile device  406  at the came frequency as updates to the mobile device  408 . Accordingly, overhead is increased. In accordance with one aspect, the base station  402  can transmit timing adjustments on a modified per-need basis to reduce overhead. Moreover, the mobile device  406  and  409  can enter a sleep mode to conserve power and periodically awaken to check for timing adjustments. 
     The techniques described herein may be used for a system  400  with sectorized cells as well as a system with un-sectorized cells. For clarity, the following description is for a system with sectorized cells. The terms “access point” and “base station” is used generically for a fixed station that serves a sector as well as a fixed station that serves a cell. The terms “terminal,” “user” and “user equipment” are used interchangeably, and the terms “sector,” “access point” and “base station” are also used interchangeably. A serving access point/sector is an access point/sector with which a terminal communicates. A neighbor access point/sector is an access point/sector with which a terminal is not in communication. 
     Referring to  FIGS. 5-6 , methodologies relating to providing uplink timing control while reducing overhead and power consumption are illustrated. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of acts, it is to be understood and appreciated that the methodologies are not limited by the order of acts, as some acts may, in accordance with one or more embodiments, occur in different orders and/or concurrently with other acts from that shown and described herein. For example, those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a methodology in accordance with one or more embodiments. 
     Turning to  FIG. 5 , illustrated is a methodology  500  that facilitates providing timing updates in a wireless communications network. In accordance with an aspect, the methodology  500  can be performed by a base station in a wireless communication environment. At reference numeral  502 , uplink information is received. For example, uplink information can be received via a transmission from a mobile device awaking from a sleep mode. In addition, the transmission can be sent while the mobile device is in the sleep mode and/or prior to entering the sleep mode. At reference numeral  504 , it is determined whether the mobile device sending the uplink information requires a timing adjustment. Pursuant to an illustration, local reference timing can be compared to the timing of the received signal carrying the uplink information. At reference numeral  506 , an appropriate timing adjustment is evaluated. For example, the timing adjustment value can be the difference between the local timing and the timing of the received uplink information. At reference numeral  508 , the timing adjustment is transmitted to the mobile device. Pursuant to an illustrative embodiment, the timing adjustment can be encapsulated in a timing adjustment command transmitted on a forward link channel. 
     Now referring to  FIG. 6 , a methodology  600  that facilitates conserving power while acquiring timing updates. In accordance with an aspect, the methodology  600  can be performed by a mobile device in a wireless communication environment. At reference numeral  602 , a sleep mode is entered. For instance, a mobile device can enter a sleep mode to conserve power and maintain only a minimal amount of signaling required to retain access to a communication system. At reference numeral  604 , a determination is made as to whether a sleep timer has expired. Pursuant to an illustration, the sleep mode is maintained for a predetermined amount of time. If the predetermined amount of time has not expired, the mobile device continues to sleep at reference numeral  602 . If, at reference numeral  604 , it is determined that the timer has expired, the methodology  600  proceeds to reference numeral  606  where the mobile device wakes up. In accordance with an embodiment, the mobile device transmits uplink information at reference numeral  606 . At reference numeral  608 , it is checked whether or not a timing adjustment command is received. If no, the methodology  600  returns to reference numeral  602  where the sleep mode is re-entered. If a timing adjustment command is received at reference numeral  608 , the methodology  600  proceeds to reference numeral  610  where uplink timing is adjust in accordance with the timing adjustment command. 
     It will be appreciated that, in accordance with one or more aspects described herein, inferences can be made regarding determining a sleep period, ascertaining a timing adjustment need, evaluating a timing adjustment values, etc. in a wireless communications network as described. As used herein, the term to “infer” or “inference” refers generally to the process of reasoning about or inferring states of the system, environment, and/or user from a set of observations as captured via events and/or data. Inference can be employed to identify a specific context or action, or can generate a probability distribution over states, for example. The inference can be probabilistic—that is, the computation of a probability distribution over states of interest based on a consideration of data and events. Inference can also refer to techniques employed for composing higher-level events from a set of events and/or data. Such inference results in the construction of new events or actions from a set of observed events and/or stored event data, whether or not the events are correlated in close temporal proximity, and whether the events and data come from one or several event and data sources. 
     According to an example, one or more methods or systems presented above can include making inferences pertaining to determining a sleep period. For example, a hopping pattern can be selected based on inferences made regarding past sleep periods and/or past timing adjustments, such as the situations in which a mobile device traveled rapidly in a sector and required more frequent adjustments. Additionally, inferences can be made with respect to determining a need for a timing update and/or evaluating a timing adjustment. 
       FIG. 7  is an illustration of a mobile device  700  that facilitates acquiring and utilizing timing adjustments. Mobile device  700  comprises a receiver  702  that receives a signal from, for instance, a receive antenna (not shown), performs typical actions on (e.g., filters, amplifies, downconverts, etc.) the received signal, and digitizes the conditioned signal to obtain samples. Receiver  702  can comprise a demodulator  704  that can demodulate received symbols and provide them to a processor  706  for channel estimation. Processor  706  can be a processor dedicated to analyzing information received by receiver  702  and/or generating information for transmission by a transmitter  716 , a processor that controls one or more components of mobile device  700 , and/or a processor that both analyzes information received by receiver  702 , generates information for transmission by transmitter  716 , and controls one or more components of mobile device  700 . 
     Mobile device  700  can additionally comprise memory  708  that is operatively coupled to processor  706  and that can store data to be transmitted, received data, information related to available channels, data associated with analyzed signal and/or interference strength, information related to an assigned channel, power, rate, or the like, and any other suitable information for estimating a channel and communicating via the channel. Memory  7018  can additionally store protocols and/or algorithms associated with estimating and/or utilizing a channel (e.g., performance based, capacity based, etc.). 
     It will be appreciated that the data store (e.g., memory  709 ) described herein can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. By way of illustration, and not limitation, nonvolatile memory can include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable PROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM), which acts as external cache memory. By way of illustration and not limitation, RAM is available in many forms such as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM). The memory  708  of the subject systems and methods is intended to comprise, without being limited to, these and any other suitable types of memory. 
     Processor  706  can further be operatively coupled to a sleep timer  710  that holds the mobile device  700  in the sleep mode until a predetermined time passes as described supra, for instance. Pursuant to an illustration, the sleep timer  710  can maintain a timer mechanism that expires after the predetermined time elapses. According to an aspect, the timer mechanism can initiate (e.g., start the clock) when the mobile device enters the sleep mode. Upon expiration of the sleep timer  710 , the mobile device  700  can awaken and determine if a timing adjustment command has issued from, for example, a base station. According to an example, the receiver  702  can read a fast physical access channel to receive a timing adjustment command if issued. 
     Mobile device  700  still further comprises a modulator  714  and transmitter  716  that respectively modulate and transmit signals to, for instance, a base station, another mobile device, etc. Pursuant to illustration, the transmitter  716  can transmit uplink information while the mobile device  700  is in a sleep mode, before the mobile device  700  enters sleep mode and/or immediately upon waking. The processor  706  can also be operatively coupled to a timing adjuster  712  that can increase, reduce, and/or configure uplink timing utilized by the transmitter  716  to transmit the uplink signals. According to an example, the mobile device  700  can receive a timing adjustment command from a base station and the timing adjuster  712  can adjust uplink timing based at least in part on the received timing adjustment command. Although depicted as being separate from the processor  706 , it is to be appreciated that the sleep timer  710 , timing adjuster  712 , demodulator  704 , and/or modulator  714  call be part of the processor  706  or multiple processors (not shown). 
       FIG. 8  is an illustration of a system  800  that facilitates evaluating, transmitting and receiving timing updates for uplink channels as described supra. The system  800  comprises a base station  802  (e.g., access point, . . . ) with a receiver  810  that receives signal(s) from one or more mobile devices  804  through a plurality of receive antennas  806 , and a transmitter  824  that transmits to the one or more mobile devices  804  through a transmit antenna  808 . Receiver  810  can receive information from receive antennas  806  and is operatively associated with a demodulator  912  that demodulates received information. Demodulated symbols are analyzed by a processor  814  that can be similar to the processor described above with regard to  FIG. 7 , and which is coupled to a memory  816  that stores information related to estimating a signal (e.g., pilot) strength and/or interference strength, data to be transmitted to or received from mobile device(s)  804  (or a disparate base station (not shown)), and/or any other suitable information related to performing the various actions and functions set forth herein. Processor  814  is further coupled to a timing adjustment determiner  818  that can ascertain if mobile devices  804  require timing updates. Moreover, the processor  814  can be coupled to a timing adjustment evaluator  820  that can generate timing adjustment commands that update timing of mobile device  804  according to the identified need. 
     According to an example, the base station  802  can receive communication from one or more mobile devices  804  and can determine a timing update need for the device  804  based on the communication. For example the timing adjustment determiner  818  can compare local reference timing of the base station  802  with timing included in the received communication. Subsequently, if uplink timing of the device  804  requires updating as described supra, the timing adjustment evaluator  820  can generate an appropriate timing adjustment command. The timing adjustment command can be transmitted to a respective mobile device  804 . Subsequently, the mobile device  804  can utilize the timing adjustment command to update uplink timing. Furthermore, although depicted as being separate from the processor  914 , it is to be appreciated that the timing adjustment determiner  818 , timing adjustment evaluator  820 , demodulator  812 , and/or modulator  822  can be part of the processor  814  or multiple processors (not shown). 
       FIG. 9  shows an example wireless communication system  900 . The wireless communication system  900  depicts one base station  910  and one mobile device  950  for sake of brevity. However, it is to be appreciated that system  900  can include more than one base station and/or more than one mobile device, wherein additional base stations and/or mobile devices can be substantially similar or different from example base station  910  and mobile device  950  described below. In addition, it is to be appreciated that base station  910  and/or mobile device  950  can employ the systems ( FIGS. 1-3  and  7 - 8 ), techniques/configurations ( FIG. 4 ) and/or methods ( FIGS. 5-6 ) described herein to facilitate-wireless communication there between. 
     At base station  910 , traffic data for a number of data streams is provided from a data source  912  to a transmit (TX) data processor  914 . According to an example, each data stream can be transmitted over a respective antenna. TX data processor  914  formats, codes, and interleaves the traffic data stream based on a particular coding scheme selected for that data stream to provide coded data. 
     The coded data for each data stream can be multiplexed with pilot data using orthogonal frequency division multiplexing (OFDM) techniques. Additionally or alternatively, the pilot symbols can be frequency division multiplexed (FDM), time division multiplexed (TDM), or code division multiplexed (CDM). The pilot data is typically a known data pattern that is processed in a known manner and can be used at mobile device  950  to estimate channel response. The multiplexed pilot and coded data for each data stream can be modulated (e.g., symbol mapped) based on a particular modulation scheme (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM), etc.) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream can be determined by instructions performed or provided by processor  930 . 
     The modulation symbols for the data streams can be provided to a TX MIMO processor  920 , which can further process the modulation symbols (e.g., for OFDM). TX MIMO processor  920  then provides N T  modulation symbol streams to N T  transmitters (TMTR)  922   a  through  922   t . In various embodiments, TX MIMO processor  920  applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted. 
     Each transmitter  922  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. Further, N T  modulated signals from transmitters  922   a  through  922   t  are transmitted from N T  antennas  924   a  through  9241 , respectively. 
     At mobile device  950 , the transmitted modulated signals are received by N R  antennas  952   a  through  952   r  and the received signal from each antenna  952  is provided to a respective receiver (RCVR)  954   a  through  954   r . Each receiver  954  conditions (e.g., filters, amplifies, and downconverts) a respective signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream. 
     An RX data processor  960  can receive and process the N R  received symbol streams from N R  receivers  954  based on a particular receiver processing technique to provide N T  “detected” symbol streams. RX data processor  960  can demodulate, deinterleave, and decode each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor  960  is complementary to that performed by TX MIMO processor  920  and TX data processor  914  at base station  910 . 
     A processor  970  can periodically determine which preceding matrix to utilize as discussed above. Further, processor  970  can formulate a reverse link message comprising a matrix index portion and a rank value portion. 
     The reverse link message can comprise various types of information regarding the communication link and/or the received data stream. The reverse link message can be processed by a TX data processor  938 , which also receives traffic data for a number of data streams from a data source  936 , modulated by a modulator  980 , conditioned by transmitters  954   a  through  954   r , and transmitted back to base station  910 . 
     At base station  910 , the modulated signals from mobile device  950  are received by antennas  924 , conditioned by receivers  922 , demodulated by a demodulator  940 , and processed by a RX data processor  942  to extract the reverse link message transmitted by mobile device  950 . Further, processor  930  can process the extracted message to determine which precoding matrix to use for determining the beamforming weights. 
     Processors  930  and  970  can direct (e.g., control, coordinate, manage, etc.) operation at base station  910  and mobile device  950 , respectively. Respective processors  930  and  970  can be associated with memory  932  and  972  that store program codes and data. Processors  930  and  970  can also perform computations to derive frequency and impulse response estimates for the uplink and downlink, respectively. 
     It is to be understood that the embodiments described herein can be implemented in hardware, software, firmware, middleware, microcode, or any combination thereof. For a hardware implementation, the processing units can be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. 
     When the embodiments are implemented in software, firmware, middleware or microcode, program code or code segments, they can be stored in a machine-readable medium, such as a storage component. A code segment can represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment can be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. can be passed, forwarded, or transmitted using any suitable means including memory sharing, message passing, token passing, network transmission, etc. 
     For a software implementation, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes can be stored in memory units and executed by processors. The memory unit can be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via various means as is known in the art. 
     With reference to  FIG. 10 , illustrated is a system  1000  that utilizes timing adjustments to control uplink timing. For example, system  1000  can reside at least partially within a base station, mobile device, etc. It is to be appreciated that system  1000  is represented as including functional blocks, which can be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System  1000  includes a logical grouping  1002  of electrical components that can act in conjunction. The logical grouping  1002  can include an electrical component for waking from a sleep mode after a predetermined period of time passes  1004 . In addition, the logical grouping  1002  can comprise an electrical component for determining whether a timing adjustment command issued  1006 . Moreover, the logical grouping  1002  can include an electrical component for adjusting uplink timing based upon the issued timing adjustment command  1008 . Additionally, system  1000  can include a memory  1010  that retains instructions for executing functions associated with electrical components  1004 ,  1006 , and  1008 . While shown as being external to memory  1010 , it is to be understood that one or more of electrical components  1004 ,  1006 , and  1008  can exist within memory  1010 . 
     Turning to  FIG. 11 , illustrated is a system  1100  that evaluates and transmits timing adjustments in a wireless communications network. System  1100  can reside within a base station, mobile device, etc., for instance. As depicted, system  1100  includes functional blocks that can represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System  1100  includes a logical grouping  1102  of electrical components that facilitate evaluating timing adjustments. Logical grouping  1102  can include an electrical component for receiving a transmission from a waking mobile device  1104 . Moreover, logical grouping  1102  can include an electrical component for determining if the waking mobile device requires a timing update  1106 . Further, logical grouping  1102  can comprise an electrical component for evaluating a timing adjustment for the waking mobile  1108 . In addition, logical grouping  1102  can include an electrical component for issuing a timing adjustment command to the waking mobile  1110 . Additionally, system  1100  can include a memory  1112  that retains instructions for executing functions associated with electrical components  1104 ,  1106 ,  1108  and  1110 . While shown as being external to memory  1112 , it is to be understood that electrical components  1104 ,  1106 ,  1108  and  1110  can exist within memory  1112 . 
     What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the tem “comprising” as “comprising” is interpreted when employed as a transitional word in a, claim.