Abstract:
Certain embodiments provide techniques for background scanning in a wireless communication device receiving signals from multiple base stations using a background scanning processor separate from a receive processor. The techniques generally include buffering raw signal data from multiple base stations, forwarding the raw signal data to a receive baseband processor for decoding data from a first one of the base stations that is currently designated as a serving base station with an active connection to the wireless communications device, forwarding the raw signal data to a background scanning processor, separate from the receive baseband processor, and generating channel characteristics corresponding to the multiple base stations with the background scanning processor without interrupting the exchange of data with the first base station designated as the serving base station.

Description:
TECHNICAL FIELD 
       [0001]    Certain embodiments of the present disclosure generally relate to wireless communication and, more particularly, to background scanning of base stations by a mobile communications device. 
       BACKGROUND 
       [0002]    OFDM and OFDMA wireless communication systems under IEEE 802.16 use a network of base stations to communicate with wireless devices (i.e., mobile stations) registered for services in the systems based on the orthogonality of frequencies of multiple subcarriers and can be implemented to achieve a number of technical advantages for wideband wireless communications, such as resistance to multipath fading and interference. Each base station (BS) emits and receives radio frequency (RF) signals that convey data to and from the mobile stations (MS). Such an RF signal from a BS includes an overhead load, in addition to the data load (voice and other data), for various communication management functions. Each MS processes the information in the overhead load of each received signal prior to processing the data. 
         [0003]    Under the current versions of the IEEE 802.16 standard for the OFDMA systems, every downlink subframe from a base station includes a preamble and a frame control header (FCH) following the preamble as part of the overhead load. The preamble includes information for searching a cell and a cell sector within a cell and for synchronizing a mobile station in both time and frequency with the received downlink signal. The FCH portion of the downlink subframe includes information on the downlink transmission format (e.g., the downlink media access protocol, or DL MAP) and control information for the downlink data reception (e.g., allocation of the subcarriers in the current downlink frame). Therefore, a receiver, such as a MS, first decodes the FCH to determine the position of the DL MAP, decodes the DL MAP of the corresponding position, and then extracts the data. 
         [0004]    If the communication quality falls below a certain threshold, a MS may start scanning for another BS with which to execute a hand-over (HO). However, under the 802.16e standard, a MS should stop transmission and reception of data to scan neighboring base stations. Accordingly, to scan for another BS, a MS may request a serving BS to allocate time intervals during which the MS may scan neighboring BSs. A MS may scan neighboring BSs by sending a MOB_SCN-REQ message in which requested scan duration, interleaving interval, and scan information may be included. 
         [0005]    A serving BS that has received a MOB_SCN-REQ may grant time intervals to the MS by sending a MOB_SCN-REP message which may include a scanning start frame and the values granted. Additionally, the BS may send unsolicited MOB_SCN-RSP messages to trigger the MS to begin neighbor BS scanning. 
         [0006]    Neighbor BS scanning is an essential function for a MS to effectuate a proper HO. It is evident that more frequent scanning of BS will improve HO performance. However, under the 802.16e standard, a MS should stop transmission and reception of data to scan neighbor base stations, meaning the BS should not send data to the MS during a scanning interval and the BS is not responsible for receiving data from the MS during a scanning interval. 
       SUMMARY 
       [0007]    Certain embodiments provide a method for background scanning in a wireless communication device receiving signals from multiple base stations. The method generally includes buffering raw signal data from multiple base stations, forwarding the raw signal data to a receive baseband processor for decoding data from a first one of the base stations that is currently designated as a serving base station with an active connection to the wireless communications device, forwarding the raw signal data to a background scanning processor, separate from the receive baseband processor, and generating channel characteristics corresponding to the multiple base stations with the background scanning processor without interrupting the exchange of data with the first base station designated as the serving base station. 
         [0008]    Certain embodiments provide a wireless communications device. The device generally includes logic for buffering raw signal data received from multiple base stations, a receive baseband processor for decoding, from the raw signal data, data from a first one of the base stations that is currently designated as a serving base station with an active connection to the wireless communications device, and a background scanning processor for generating channel characteristics corresponding to the multiple base stations without interrupting the exchange of data with the first base station designated as the serving base station. 
         [0009]    Certain embodiments provide an apparatus for wireless communications. The apparatus generally includes means for buffering raw signal data received from multiple base stations, means for decoding, from the raw signal data, data from a first one of the base stations that is currently designated as a serving base station with an active connection to the wireless communications device, and means for generating, based on the raw signal data, channel characteristics corresponding to the multiple base stations without interrupting the exchange of data with the first base station designated as the serving base station. 
         [0010]    Certain embodiments provide a computer-readable medium containing a program for background scanning in a wireless communication device receiving signals from multiple base stations. When executed by a processor, the program performs operations generally including receiving raw signal data from multiple base stations, and generating channel characteristics corresponding to the multiple base stations without interrupting the exchange of data between the wireless communications device and a first one of the base stations designated as a serving base station. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective embodiments. 
           [0012]      FIG. 1  illustrates an example wireless communication system, in accordance with certain embodiments of the present disclosure. 
           [0013]      FIG. 2  illustrates various components that may be utilized in a wireless device in accordance with certain embodiments of the present disclosure. 
           [0014]      FIG. 3  illustrates an example transmitter and an example receiver that may be used within a wireless communication system that utilizes orthogonal frequency-division multiplexing and orthogonal frequency division multiple access (OFDM/OFDMA) technology in accordance with certain embodiments of the present disclosure. 
           [0015]      FIG. 4  illustrates example operations of a MS that may maintain data throughput while performing neighboring BS scanning, in accordance with embodiments of the present disclosure. 
           [0016]      FIG. 4A  is a block diagram of means corresponding to the example operations of  FIG. 4  for maintaining data throughput while performing neighboring BS scanning, in accordance with embodiments of the present disclosure 
           [0017]      FIG. 5  illustrates an example MS with a BKG processor, in accordance with embodiments of the present disclosure. 
           [0018]      FIGS. 6A-6D  illustrate a block diagram of example operations, in accordance with embodiments of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Embodiments of the present disclosure enable a MS to perform background (BKG) scanning of neighboring BSs without stopping data exchange with a serving BS. The implementation of BKG scanning may eliminate the trade-off between HO performance and data throughput performance. 
       Exemplary Wireless Communication System 
       [0020]    The methods and apparatus of the present disclosure may be utilized in a broadband wireless communication system. As used herein, the term “broadband wireless” generally refers to technology that may provide any combination of wireless services, such as voice, Internet and/or data network access over a given area. 
         [0021]    WiMAX, which stands for the Worldwide Interoperability for Microwave Access, is a standards-based broadband wireless technology that provides high-throughput broadband connections over long distances. There are two main applications of WiMAX today: fixed WiMAX and mobile WiMAX. Fixed WiMAX applications are point-to-multipoint, enabling broadband access to homes and businesses, for example. Mobile WiMAX offers the full mobility of cellular networks at broadband speeds. 
         [0022]    Mobile WiMAX is based on OFDM (orthogonal frequency-division multiplexing) and OFDMA (orthogonal frequency division multiple access) technology. OFDM is a digital multi-carrier modulation technique that has recently found wide adoption in a variety of high-data-rate communication systems. With OFDM, a transmit bit stream is divided into multiple lower-rate substreams. Each substream is modulated with one of multiple orthogonal subcarriers and sent over one of a plurality of parallel subchannels. OFDMA is a multiple access technique in which users are assigned subcarriers in different time slots. OFDMA is a flexible multiple-access technique that can accommodate many users with widely varying applications, data rates, and quality of service requirements. 
         [0023]    The rapid growth in wireless internets and communications has led to an increasing demand for high data rate in the field of wireless communications services. OFDM/OFDMA systems are today regarded as one of the most promising research areas and as a key technology for the next generation of wireless communications. This is due to the fact that OFDM/OFDMA modulation schemes can provide many advantages such as modulation efficiency, spectrum efficiency, flexibility and strong multipath immunity over conventional single carrier modulation schemes. 
         [0024]    IEEE 802.16x is an emerging standard organization to define an air interface for fixed and mobile broadband wireless access (BWA) systems. These standards define at least four different physical layers (PHYs) and one media access control (MAC) layer. The OFDM and OFDMA physical layer of the four physical layers are the most popular in the fixed and mobile BWA areas respectively. 
         [0025]      FIG. 1  illustrates an example of a wireless communication system  100  in which embodiments of the present disclosure may be employed. The wireless communication system  100  may be a broadband wireless communication system. The wireless communication system  100  may provide communication for a number of cells  102 , each of which is serviced by a base station  104 . A base station  104  may be a fixed station that communicates with user terminals  106 . The base station  104  may alternatively be referred to as an access point, a Node B or some other terminology. 
         [0026]      FIG. 1  depicts various user terminals  106  dispersed throughout the system  100 . The user terminals  106  may be fixed (i.e., stationary) or mobile. The user terminals  106  may alternatively be referred to as remote stations, access terminals, terminals, subscriber units, mobile stations, stations, user equipment, etc. The user terminals  106  may be wireless devices, such as cellular phones, personal digital assistants (PDAs), handheld devices, wireless modems, laptop computers, personal computers, etc. 
         [0027]    A variety of algorithms and methods may be used for transmissions in the wireless communication system  100  between the base stations  104  and the user terminals  106 . For example, signals may be sent and received between the base stations  104  and the user terminals  106  in accordance with OFDM/OFDMA techniques. If this is the case, the wireless communication system  100  may be referred to as an OFDM/OFDMA system. 
         [0028]    A communication link that facilitates transmission from a base station  104  to a user terminal  106  may be referred to as a downlink  108 , and a communication link that facilitates transmission from a user terminal  106  to a base station  104  may be referred to as an uplink  110 . Alternatively, a downlink  108  may be referred to as a forward link or a forward channel, and an uplink  110  may be referred to as a reverse link or a reverse channel. 
         [0029]    A cell  102  may be divided into multiple sectors  112 . A sector  112  is a physical coverage area within a cell  102 . Base stations  104  within a wireless communication system  100  may utilize antennas that concentrate the flow of power within a particular sector  112  of the cell  102 . Such antennas may be referred to as directional antennas. 
         [0030]      FIG. 2  illustrates various components that may be utilized in a wireless device  202  that may be employed within the wireless communication system  100 . The wireless device  202  is an example of a device that may be configured to implement the various methods described herein. The wireless device  202  may be a base station  104  or a user terminal  106 . 
         [0031]    The wireless device  202  may include a processor  204  which controls operation of the wireless device  202 . The processor  204  may also be referred to as a central processing unit (CPU). Memory  206 , which may include both read-only memory (ROM) and random access memory (RAM), provides instructions and data to the processor  204 . A portion of the memory  206  may also include non-volatile random access memory (NVRAM). The processor  204  typically performs logical and arithmetic operations based on program instructions stored within the memory  206 . The instructions in the memory  206  may be executable to implement the methods described herein. 
         [0032]    The wireless device  202  may also include a housing  208  that may include a transmitter  210  and a receiver  212  to allow transmission and reception of data between the wireless device  202  and a remote location. The transmitter  210  and receiver  212  may be combined into a transceiver  214 . An antenna  216  may be attached to the housing  208  and electrically coupled to the transceiver  214 . The wireless device  202  may also include (not shown) multiple transmitters, multiple receivers, multiple transceivers, and/or multiple antennas. 
         [0033]    The wireless device  202  may also include a signal detector  218  that may be used in an effort to detect and quantify the level of signals received by the transceiver  214 . The signal detector  218  may detect such signals as total energy, pilot energy from pilot sub-carriers or signal energy from preamble symbol, power spectral density and other signals. The wireless device  202  may also include a digital signal processor (DSP)  220  for use in processing signals. 
         [0034]    The various components of the wireless device  202  may be coupled together by a bus system  222 , which may include a power bus, a control signal bus, and a status signal bus in addition to a data bus. 
         [0035]      FIG. 3  illustrates an example of a transmitter  302  that may be used within a wireless communication system  100  that utilizes OFDM/OFDMA. Portions of the transmitter  302  may be implemented in the transmitter  210  of a wireless device  202 . The transmitter  302  may be implemented in a base station  104  for transmitting data  306  to a user terminal  106  on a downlink  108 . The transmitter  302  may also be implemented in a user terminal  106  for transmitting data  306  to a base station  104  on an uplink  110 . 
         [0036]    Data  306  to be transmitted is shown being provided as input to a serial-to-parallel (S/P) converter  308 . The S/P converter  308  may split the transmission data into N parallel data streams  310 . 
         [0037]    The N parallel data streams  310  may then be provided as input to a mapper  312 . The mapper  312  may map the N parallel data streams  310  onto N constellation points. The mapping may be done using some modulation constellation, such as binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), 8 phase-shift keying (8PSK), quadrature amplitude modulation (QAM), etc. Thus, the mapper  312  may output N parallel symbol streams  316 , each symbol stream  316  corresponding to one of the N orthogonal subcarriers of the inverse fast Fourier transform (IFFT)  320 . These N parallel symbol streams  316  are represented in the frequency domain and may be converted into N parallel time domain sample streams  318  by an IFFT component  320 . 
         [0038]    A brief note about terminology will now be provided. N parallel modulations in the frequency domain are equal to N modulation symbols in the frequency domain, which are equal to N mapping and N-point IFFT in the frequency domain, which is equal to one (useful) OFDM symbol in the time domain, which is equal to N samples in the time domain. One OFDM symbol in the time domain, N s , is equal to N cp  (the number of guard samples per OFDM symbol)+N (the number of useful samples per OFDM symbol). 
         [0039]    The N parallel time domain sample streams  318  may be converted into an OFDM/OFDMA symbol stream  322  by a parallel-to-serial (P/S) converter  324 . A guard insertion component  326  may insert a guard interval between successive OFDM/OFDMA symbols in the OFDM/OFDMA symbol stream  322 . The output of the guard insertion component  326  may then be upconverted to a desired transmit frequency band by a radio frequency (RF) front end  328 . An antenna  330  may then transmit the resulting signal  332 . 
         [0040]      FIG. 3  also illustrates an example of a receiver  304  that may be used within a wireless device  202  that utilizes OFDM/OFDMA. Portions of the receiver  304  may be implemented in the receiver  212  of a wireless device  202 . The receiver  304  may be implemented in a user terminal  106  for receiving data  306  from a base station  104  on a downlink  108 . The receiver  304  may also be implemented in a base station  104  for receiving data  306  from a user terminal  106  on an uplink  110 . 
         [0041]    The transmitted signal  332  is shown traveling over a wireless channel  334 . When a signal  332 ′ is received by an antenna  330 ′, the received signal  332 ′ may be downconverted to a baseband signal by an RF front end  328 ′. A guard removal component  326 ′ may then remove the guard interval that was inserted between OFDM/OFDMA symbols by the guard insertion component  326 . 
         [0042]    The output of the guard removal component  326 ′ may be provided to an S/P converter  324 ′. The S/P converter  324 ′ may divide the OFDM/OFDMA symbol stream  322 ′ into the N parallel time-domain symbol streams  318 ′, each of which corresponds to one of the N orthogonal subcarriers. A fast Fourier transform (FFT) component  320 ′ may convert the N parallel time-domain symbol streams  318 ′ into the frequency domain and output N parallel frequency-domain symbol streams  316 ′. 
         [0043]    A demapper  312 ′ may perform the inverse of the symbol mapping operation that was performed by the mapper  312  thereby outputting N parallel data streams  310 ′. A P/S converter  308 ′ may combine the N parallel data streams  310 ′ into a single data stream  306 ′. Ideally, this data stream  306 ′ corresponds to the data  306  that was provided as input to the transmitter  302 . Note that elements  308 ′,  310 ′,  312 ′,  316 ′,  320 ′,  318 ′ and  324 ′ may all be found on a in a baseband processor  340 ′. 
       Neighbor Base Station Scanning 
       [0044]    As a MS moves within a cell, or between cells, the characteristics of one or more of the signals received by the MS may change. Since the data being received is not bound to a specific BS, the MS may utilize a handoff mechanism that determines the ideal BS with which to communicate. 
         [0045]    In accordance with the 802.16e standard, a conventional MS may request a scanning period from the serving BS to decode and evaluate the channel characteristics of signals from neighboring BSs. A conventional MS will typically cease data transmission and reception during the scanning period, thereby reducing overall throughput. Consequently, a trade-off may develop between ensuring high signal quality by performing neighboring BS scanning to properly effectuate handoffs and maintaining data throughput performance. In other words, more frequent scanning of neighboring BSs will improve HO performance and signal quality, but performing the scanning and associated HO operations may significantly hinder the data throughput. 
         [0046]    Embodiments of the present disclosure, however, provide a receiver architecture that may allow background scanning to be performed with a reduced impact on data throughput. The background scanning may be performed in accordance with the operations  400  shown in  FIG. 4  utilizing the architecture. As illustrated in  FIG. 5 , the architecture may include a separate baseband processor for background scanning, in addition to a receiver baseband processing. By “offloading” scanning operations to this separate processor, a connection with a serving base station may be maintained while scanning neighboring base stations. 
         [0047]    Referring to  FIG. 4 , the example operations  400  for background scanning that may be performed by an MS with a separate baseband processor will be described. The operations may help maintain data throughput while performing neighboring BS scanning. The operations  400  may be described with reference to components found in  FIG. 5 . 
         [0048]    The operations begin, at  402 , with an MS receiving OFDM(A) transmission signals from multiple base stations. The transmission signals may correspond to one or more frames of data and, thus, may include a frame control header (FCH) and corresponding data bursts. As illustrated, the architecture may utilize a conventional RF front end  328 ′ to downconvert the received signal to a baseband signal and then remove the accompanying guard interval. 
         [0049]    At  404 , raw data received by the MS, which may include all “over the air” information captured by the receiver, is stored in a sample buffer. For example, the architecture may include a sample buffer  510  that may be any suitable type buffer, such as an in-phaser, quadrature-phaser (IQ) or intermediate frequency (IF) sample buffer which may be accessed from multiple decoder blocks. 
         [0050]    At  406 , the stored data may then be forwarded to a conventional reception (Rx) baseband processor  540 , as well as a background (BKG) processor  520 . Utilizing the sample buffer  510  and separate baseband processor  520 , a connection with the serving base station may be maintained, allowing the exchange of data while performing background scanning operations in parallel. 
         [0051]    At  408 , the MS continues to exchange data with a serving BS, using the RX processor  540  to process the received signal. After decoding the stored data, at  410 , the Rx processor  540  may forward data packet received from the serving BS to additional logic or applications downstream. The exchange of data between the BS and the MS may require the RX processor  540  to perform one or more conventional processing functions (e.g., fast Fourier transforms (FFT), demodulation and decoding). Note that conventional processing functions typically filter out a majority of the information from neighboring (non-serving) BSs in an effort to improve Rx performance. 
         [0052]    As data is being exchanged with the RX processor  540 , at  412 , BKG processor  520  may process the raw buffered data to generate and/or extract channel information for the serving base station and one or more neighboring BSs may be extracted. The BKG processor  520  may perform any suitable operations to process the buffered data and generate information useful in performing a handoff between base stations. 
         [0053]    For example, the BKG processor  520  may measure the received signal strength indicator (RSSI), the carrier-to-interference plus noise ratio (CINR), and any suitable type measurements that may prove useful for characterizing each segment of the RF sub-carriers while the Rx processor  540  is decoding the data received from the serving BS. 
         [0054]    The BKG processor  520  may then send the channel characteristics for the various BSs being monitored to additional logic (e.g., the HO mechanism) for additional processing. For some embodiments, the HO mechanism may use the channel information forwarded from the BKG processor  520  to determine the preferred BS to use as a serving BS with which to exchange data. 
         [0055]    Because the sample buffer  510  includes all the information received by the MS, the BKG processor  520  may examine the buffered raw data and extract any information deemed necessary. In fact, the BKG processor  520  may perform any required processing with the exclusion of decoding the data received from the serving BS, which is performed by the Rx processor  540 . 
         [0056]    For example, in some embodiments the BKG processor  520  may contain the necessary logic to act as the HO mechanism. In other words, the BKG processor  520  may also evaluate the channel information from the serving and neighboring BSs, determine if a HO is desirable, and, if so, effectuate a HO. In other embodiments, the BKG processor  520  may update an HO trigger metric table to reflect the channel characteristic information. The HO trigger metric table may be used by a separate HO mechanism to determine if a HO is desirable, and, if so, effectuate a HO. The HO mechanism may evaluate characteristics (e.g., CINR, RSSI, and bit error rates) of the various signals and determine when the MS should effectuate a HO. 
         [0057]    If the BKG processor  520  is too slow or if there is too much information to process before the arrival of a subsequent frame, an additional sample buffer  510 ′ may be employed to hold a copy of the received data for one or more additional frames. In such embodiments, source selection logic may also be employed for use with the BKG processor  520 . 
         [0058]      FIGS. 6A-6C  illustrate the parallel processing flow that may be performed by the architecture shown in  FIG. 5  to when background scanning using the BKG baseband processor  520 . The Figures assume an initial serving Base Station (BS A ) and two neighboring Base Stations (BS B  and BS C ) and that BS A  initially has the best signal quality of the three. 
         [0059]    As illustrated in  FIG. 6A , signals from all three BSs are received by the MS. The sample buffer  510  may be used to store all the “raw data” information  604  received by the MS, which may then be forwarded in parallel to the RX processor  540  and the BKG processor  520 . Because BS A  is the serving station, RX BB Processor  540  will filter out data from the other base stations, and decode the data received from BS A . BKG processor  520 , on the other hand, will perform background scanning by processing data from all three base stations to generate corresponding channel condition information that may be used to affect a handoff. 
         [0060]    As illustrated in  FIG. 6B , as long as the BKG processor indicates channel conditions for BS A  are better than channel conditions for BS B  and BS C , BS A  will remain the serving station. Thus, as illustrated Rx processor  540  will continue to process data from BS A  and forward data packets  606  from BS A  to additional logic or applications downstream. In the present example, the initial serving BS is BS A . BS A  may be selected as the initial serving BS based on default settings of the MS, by signal analysis during the BS/MS registration process, or any other suitable technique. 
         [0061]    As channel conditions change, for example, due to movement by the mobile station, BKG processor  520  will continue to process raw data  604  received from multiple base stations to determine updated channel conditions in the background. At some point, BKG processor  520  may evaluate the channel information from the serving and neighboring BSs and determine that channel conditions for a neighboring station are better than for a current serving station. For some embodiments, BKG processor  520  may update HO trigger metric tables used by a separate HO mechanism to determine if a HO is desirable. 
         [0062]    As illustrated in  FIG. 6C , the BKG processor  520  may determine that channel conditions for a neighboring station BS B  are better than the current serving station BS B  and may update channel information to inform the HO mechanism accordingly. Until the HO mechanism affects the handoff and communicates to the RX processor  540 , however, the RX processor  540  may continue to process data from BS A . 
         [0063]    As illustrated in  FIG. 6D , however, after the HO mechanism processes the updated channel information that indicates better channel conditions for BS B , the HO mechanism may signal the RX processor  540  to affect a handoff (e.g., via a message/signal  608 ). Thus, after the HO has been performed to switch to BS B  as the serving station Rx processor  540  begins to filter out data from neighboring stations BS A  and BS C . RX processor  540  will process data from new serving station BS B  and forward the data packets  606  from BS B  to additional logic or applications downstream. The handoff procedure described herein may take place, for example, when a user terminal  106  moves across boundaries of cells  102  serviced by different base stations  104 . 
         [0064]    The various operations of methods described above may be performed by various hardware and/or software component(s) and/or module(s) corresponding to means-plus-function blocks illustrated in the Figures. Generally, where there are methods illustrated in Figures having corresponding counterpart means-plus-function Figures, the operation blocks correspond to means-plus-function blocks with similar numbering. For example, blocks  402 - 414  illustrated in  FIG. 4  correspond to means-plus-function blocks  402 A- 414 A illustrated in  FIG. 4A . 
         [0065]    As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may 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” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like. 
         [0066]    Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals and the like that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles or any combination thereof. 
         [0067]    The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array signal (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
         [0068]    The steps of a method or algorithm described in connection with the present disclosure may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in any form of storage medium that is known in the art. Some examples of storage media that may be used include random access memory (RAM), read only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM and so forth. A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. A storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. 
         [0069]    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 specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. 
         [0070]    The functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as instructions or as one or more sets of instructions on a computer-readable medium or storage medium. A storage media may be any available media that can be accessed by a computer or by one or more processing devices. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, include 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. 
         [0071]    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. 
         [0072]    Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can 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 storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.), such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized. 
         [0073]    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 methods and apparatus described above without departing from the scope of the claims.