Abstract:
A method and apparatus for optimization of a modem for high data rate applications comprise a plurality of hardware accelerators which are configured to perform data processing functions, wherein the hardware accelerators are parameterized, a processor is configured to selectively activate accelerators according to the desired function to conserve power requirements and a shared memory configured for communication between the plurality of hardware accelerators.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/980,826, filed Oct. 18, 2007 and U.S. Provisional Application No. 61/012,605, filed Dec. 10, 2007, which are incorporated by reference as if fully set forth. 
    
    
     FIELD OF INVENTION 
     This application is related to wireless communications. 
     BACKGROUND 
     With advances in wireless technology, 3G networks are enabling network operators to offer users a wider range of more advanced services while achieving greater network capacity through improved spectral efficiency. These services include not only improved voice calls, but multimedia messaging, and broadband wireless data, all in a mobile environment. The Third Generation Partnership Project (3GPP) Long Term Evolution (LTE), for example, may offer downlink peak rates of at least 100 Mbit/s, 50 Mbit/s in the uplink and RAN (Radio Access Network). 
     As wireless mobile equipment becomes more data centric, increases in required data rates are outpacing improvements in central processing unit (CPU) clock speeds (and power efficiency at the speeds). The 3GPP standards body continues to develop additional features and capabilities to provide these higher data rates. At the same time, users are demanding smaller and more power efficient designs. The modem footprint and power consumption must not grow in proportion with data rates. Accordingly, an extensible architecture is desired for supporting the 3GPP evolution while meeting the user requirements for efficient design. 
     SUMMARY 
     A method and apparatus for optimization of a wireless modem are disclosed. A plurality of hardware accelerators are configured to perform data processing functions, wherein the hardware accelerators are parameterized. A processor is configured to selectively activate the plurality of hardware accelerators according to the desired function, and a shared memory is selectively configured for communication between the plurality of hardware accelerators. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: 
         FIG. 1  shows a wireless communication system  100  including a plurality of WTRUs  110 , a base station  120 , and an RNC  130 ; 
         FIG. 1A  is a functional block diagram  200  of a WTRU  110  and the base station  120  of the wireless communication system  100  of  FIG. 1 ; 
         FIG. 2  is a block diagram of a modem; 
         FIG. 3  shows an embodiment of the modem of  FIG. 2 ; 
         FIG. 4  shows the Shared Memory Arbiter (SMA) of  FIG. 1 ; 
         FIG. 5  shows a flow diagram of method of HW acceleration of downlink data; 
         FIG. 6  shows a flow diagram of a method of HW acceleration in the uplink; and 
         FIGS. 7A and 7B  show a modem partitioned into different power domains to achieve more effective power management and power conservation. 
     
    
    
     DETAILED DESCRIPTION 
     When referred to hereafter, the terminology “wireless transmit/receive unit (WTRU)” includes but is not limited to a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. When referred to hereafter, the terminology “base station” includes but is not limited to a Node-B, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment. 
       FIG. 1  shows a wireless communication system  200  including a plurality of WTRUs  110 , a base station  120 , and an RNC  130 . As shown in  FIG. 1 , the WTRUs  110  are in communication with the base station  120 , which is in communication with the RNC  130 . Although three WTRUs  110 , one base station  120 , and one RNC  130  are shown in  FIG. 1 , it should be noted that any combination of wireless and wired devices may be included in the wireless communication system  100 . For example, although the RNC  130  is shown in the wireless communication system  100 , the RNC  130  may not be included in an LTE system. 
       FIG. 1A  is a functional block diagram of a WTRU  110  and the base station  120  of the wireless communication system  100  of  FIG. 1 . As shown in  FIG. 1A , the WTRU  110  is in communication with the base station  120  and both are configured to perform a method for optimizing a modem for high data rate applications. 
     In addition to the components that may be found in a typical WTRU, the WTRU  110  includes a processor  115 , a receiver  116 , a transmitter  117 , an antenna  118 , a hardware acceleration module  119 , a memory module  121 , and a modem  122 . The processor  115  is configured to perform a method for optimizing a modem for high data rate applications. The receiver  116  and the transmitter  117  are in communication with the processor  115 . The antenna  118  is in communication with both the receiver  116  and the transmitter  117  to facilitate the transmission and reception of wireless data. 
     In addition to the components that may be found in a typical base station, the base station  120  includes a processor  125 , a receiver  126 , a transmitter  127 , and an antenna  128 . The processor  125  is configured to perform a method for optimizing a modem for high data rate applications. The receiver  126  and the transmitter  127  are in communication with the processor  125 . The antenna  128  is in communication with both the receiver  126  and the transmitter  127  to facilitate the transmission and reception of wireless data. 
     When referred to hereinafter, the term hardware accelerator  119  may be used to refer to any modules within the hardware accelerator  119 . 
     When referred to hereinafter, processor  115  may be used to refer to any of the modules within the processor  115 . 
       FIG. 2  shows a block diagram of a modem  200  including a processor  115 , a shared memory arbiter (SMA)  320 , shared memory (SM)  350 , and a plurality of HW accelerators  119 . The processor  115  may be configured to perform Layer 1 (L1), Layer 2 (L2), and Layer 3 (L3) processing. The HW accelerators  119  may be configured and activated by the processor  115 . The hardware accelerators  119  may be configured to handle modem data (i.e. voice and data traffic), while the processor  115  may be configured to provide control using parameters that control how the modem data passes through the hardware accelerators  119  and not through the processor  115 . Accordingly, as shown in  FIG. 2 , modem data primarily passes through the hardware accelerators  119 . The hardware accelerators  119  may further be configured to pass data to other hardware accelerators  119  through the SM  350 . The SMA  320  controls the hardware accelerators&#39;  119  access to the SM  350 . Accordingly modem data may be processed through the hardware accelerators  119  without requiring the modem data to pass through the processor  115 . 
     Each hardware accelerator  119  or sub-system (multiple hardware accelerators  119 ) may be semi-autonomous, meaning that a start signal may power-up the appropriate hardware accelerators  119  and initiate processing. As a result, processor  115  loading may grow only minimally with increasing data rate. Signal processing functions may also be implemented in the hardware accelerators  119 . Upon completion of a task, clocks and power domains may be turned off. Each of the hardware accelerators  119  may be programmed to signal an indication to other hardware accelerators  119  when they complete a particular task. By allowing each of the hardware accelerators  119  to start other hardware accelerators  119 , the processor  115  may be more autonomous from the hardware accelerators  119 . 
       FIG. 3  shows one example of the modem of  FIG. 2 . The functionality of the processor  115  shown in  FIG. 2  may be split up into multiple modules. The processor  115  may comprise an L23 protocol stack module  301 , an L1 manager and scheduler  302 , a Transmission (Tx) Frame software (SW) module  303 , a Tx Chip SW module  304 , a radio interface processor (RIP) and Digital Front End (DFE) SW module  305 , an L1 Debug Agent Module  306 , a Receive (Rx) Frame SW module  307 , an Rx Chip/Rake Manager  308  an Automatic Frequency Control (AFC) SW module  309 , a cell search (CS) module  310 , and an Automatic Gain Control (AGC) SW module  311 . The functionality of the hardware accelerators  119  as shown in  FIG. 2  may be further divided among a plurality of hardware accelerators shown in  FIG. 3 , the hardware accelerators  119  include a Protocol Engine (PE)  321 , a DRAM Shared Memory Arbiter (DSMA)  322 , a Memory Controller  323 , a Tx Frame HW module  324 , a Tx Chip HW module  325 , a DFE HW module  326 , a timing manager  327 , a sleep timer  328 , an AGC HW module  329 , an indicator channel (ICH) module  330 , a Path Search module  331 , an HS-SCCH/AGCH module  332 , an L1 Feedback Module  333 , a channel estimation enhanced normalized least mean squares (CE-NLMS) module  334 , a Rake module  335 , an Rx Frame HW and MAC-hs module  336 , an AFC HW module  337 , a cell search HW module  338 , and a universal serial interface (USIF) module  339 . The HW accelerators  119  may be configured and activated by the modules of the processor  115 . 
     The SM  350  may be configured to provide data connectivity between hardware accelerators  119 , to provide configuration of the hardware accelerators  119  via a processor  115 , and as an interface to a host processor. The SM  350  and the SMA  320  may allow efficient extensibility by allowing memory to be shared in support of functions that operate in mutually exclusive states. Buffer space is allocated in the SM  350 . Buffers may provide memory storage for component input and outputs. The SM  350  may be partitioned to provide reuse of buffers for processes that do not run at the same time. 
     In order to reduce or eliminate traffic data from entering the processor  115 , the HW accelerators  119  may be programmed and scheduled to autonomously process data. The timing manager  327  may be configured to issue start pulses when fine-grained timing is needed. A linked list of control blocks may be configured to de-couple setup and execution of the hardware accelerators  119 . Control of the components may be configured a frame ahead of time, wherein the hardware accelerators  119  may be configured to interrupt the processor  115  upon completion of a function, or at an end of the linked list of control blocks. Upon completion of a task, a hardware accelerator  119  may be configured to trigger operation of another hardware accelerator  119 . 
       FIG. 4  shows the SMA  320 . As shown in  FIG. 4 , the SMA  320  may be configured to communicate with a plurality of other modules including the Tx Frame HW module  324 , the Tx Chip SW module  304 , the CS module  338 , the timing manager  327 , a Layer 2 &amp; 3 CPU  405 , a Layer 1 CPU  406 , a host interface  407 , an Rx AGC module  408 , an Rx Transceiver 2  module  409 , an Rx Comp 2  module  410 , an Rx Transceiver 1  module  411 , an Rx Comp 1  module  412 , an Rx Chip  413 , a CAP/DAP memory  404 , a WAP memory  403 , an internal memory  402 , and an external memory  401 . The SMA  320  may be configured to control access to memory shared by any hardware accelerator  119 , the processor  115 , and a host interface. The SMA  320  may comprise address registers and sequencing logic. The SMA  320  may be configured to allow the hardware accelerators  119  and the processor  115  to efficiently share access to available memory  350 . The external memory  401  may be added to extend the amount of available SDRAM. 
     The SM  350  may comprise the WAP memory  403  and the CAP/DAP memory  404 . The SM  350  may be configured to store pointers that are written to the SMA  320 . The CAP/DAP memory  404  may be configured to store pointers for SMA channels that are used to read control information. The CAP/DAP memory  404  may further be configured to store pointers for SMA channels that are used to read/write data. 
     The timing manager  327  may be configured to maintain system time and to create pulses based on specific frame/slot/chip times. The pulses may be used to start modules and/or create interrupts. The timing manager  327  may also include controller, (e.g. ARM interrupt controllers). The signal output by the timing manager  327  may be used by the Layer 1 manager and scheduler  203  to synchronize the operation of all other modules. 
     The sleep timer  328  may be configured to provide the countdown and mechanism to power the modules of the modem  122  (e.g. when the L1 CPU  406  enters a sleep state). The sleep timer  328  may be configured to utilize a low-power, low-accuracy 32.768 kHz real-time clock (RTC) to count during sleep. Higher precision may be obtained by calibrating the RTC against a more accurate microcontroller when the 3G L1 CPU  406  is awake in-between sleep cycles. 
     Referring to  FIG. 4 , the L1 CPU  406  may be configured to enter sleep states if a cell search fails after initialization, in frequency division duplexing (FDD) discontinuous reception (DRX) mode, or in GSM mode. 
     Referring back to  FIG. 3 , the Tx Frame HW module  324  and the Tx Frame SW  303  may collectively be referred to as a Tx Frame component. The Tx Frame HW module  324  may be configured to perform symbol rate processing on transport and composite channels for FDD uplink (E-DCH and DCH). The Tx Frame HW module  324  may accept data in transport blocks from Layer 2/3 and map this data to physical channels. Data is sent to the Tx Chip HW module  325  via the SMA  320 . 
     The Tx Chip SW module  304  and the Tx Chip HW module  325  may be collectively referred to as the Tx Chip component. The Tx Chip HW module  325  may be configured to process coded binary data from Tx Frame HW module  324  along with control channel information to properly format data for uplink transmission through the Radio Interface. The Tx Chip component may be configured to handle transmit power control and transmit timing functions. The Tx Chip component may also be configured to processes data on a Physical Random Access Channel (PRACH), Dedicated Physical Data Channel (DPDCH)/Dedicated Physical Control Channel (DPCCH), High-Speed DPCCH (HS-DPCCH), and Enhanced DPCCH (E-DPDCH)/DPCCH. The Tx Chip component may be further configured to transmit data to the DFE HW module  326 . 
     The CS HW module  338  and the CS Search SW  310  may be collectively referred to as a CS component. The CS HW module  338  may be configured to perform initial cell selection (ICS) procedure. The ICS procedure includes detecting the strongest cell when no cell identifier or timing information is known, and determining whether or not Space Time Transmit Diversity (STTD) is utilized on that cell. The CS HW module  338  may be configured to provide synchronization information for the found cell. The CS HW module  338  may further be configured to perform neighbor or serving cell measurements, which comprises detection, identification, and measurement of listed and unlisted intra-frequency neighbor cells and listed inter-frequency neighbor cells, and measurement of the serving cell. Measurements may include Common Pilot Channel (CPICH) Received Signal Code Power (RSCP); CPICH received pilot energy to total spectral density ratio (Ec/Io), and determination of the first significant path for each cell. As part of a CPICH Ec/Io determination procedure, the CS HW module  338  may be configured to measure a Received Signal Strength Indicator (RSSI) on each frequency. The CS HW module  338  may further be configured to perform a targeted cell search (TCS) procedure. The TCS procedure may comprise detection and synchronization to a particular cell (used for handover to cells that have not recently been measured). The CS HW module  338  may further be configured to perform a Public Land Mobile Network (PLMN) ID search on Universal Mobile Telecommunications System (UMTS) cell in a UMTS only mode. The CS HW module  338  may further be configured to perform GSM Inter-RAT Measurements and PLMN ID search in UMTS neighbors. 
     The AGC SW  311  and the AGC HW module  329  may be collectively referred to as an AGC component. The AGC HW module  329  may be configured to control the signal power level seen at an Analog to Digital Converter (ADC) input, which may be coupled to the DFE HW module  326 . Alternatively the AGC component may be configured to adhere to the DigRF standard. 
     The AFC HW module  337  and the AFC SW  309  may be collectively referred to as the AFC component. The AFC HW module  337  may be configured to provide an estimated carrier frequency offset error signal, between the base station  120  and the WTRU  110 , to a WTRU  110  radio interface. 
     The AGC HW module  329  and the AGC SW module  311  collectively may be referred to as the AGC component. The AGC component may be configured to support both a primary receive path and a diversity receive path. The AFC HW module  337  may be configured to estimate and cancel the carrier frequency offset on the received signal. The AFC HW module  337  operates only on a main radio temperature controlled crystal oscillator (a single clock is distributed to both radios). 
     The RIP and DFE SW module  305  and the DFE HW module  326  may collectively be referred to as the radio interface component. The radio interface component may be configured to connect 2G/3G radios to the modem front end. The radio interface component may be configured to provide parallel transmit and receive I/Q data paths over which data is transferred between the modem and the radio. Additional control interfaces may initialize the radios and transfer control information between the radio and the modem. The radio interface component may be configured for communication via three separate radio interfaces including a 3G main radio interface, a 3G diversity radio interface, and a 2G radio interface. The radio interface component may comprise a three-wire interface for programming and enabling the receiver for each radio interface. The three-wire interface (clock, data, and enable) is a bi-directional synchronous serial bus which provides the capability to access multiple devices using an address/data protocol. This three-wire interface provides separate enables for each radio. The radio interface component may further be configured to provide the capability of enabling a second radio (via the 3-wire interface) to provide a diversity path (or multi-path) in 3G mode on the receive side in order to increase performance with HSDPA. 
     The RIP  305  may be programmable and is compatible with a wide variety of radios. The RIP  305  may be configured to perform data transfers and logic operations and controls the three-wire interface to any 3G radios. The RIP  305  may also provide controls on the radio interface for frequency selection and gain control, transmit power control (TPC) and power amp bias control, and for switching the antenna at the radio output between 3G and GSM mode. 
     The DFE HW module  326  may comprise a receive DFE (Rx DFE) and a transmit paths DFE (Tx DFE). The DFE HW module  326  may be configured to filter and correct 3G digital signals on the Rx DFE and the Tx DFE. The modem  122  may include independent DFE chains for both primary and diversity radio receivers. The Rx DFE may be configured to perform for low-pass filtering and decimating over-sampled and noise-shaped signals from an analog front end (AFE), removing DC offsets, and performing final band-selection and pulse shaping. The Tx DFE may be configured to perform pulse shaping, DC offset and IQ-amplitude correction, up sampling, and noise shaping before applying the signal to the AFE. 
     The Rx Chip/Rake Manager  308  may be configured to perform demodulation and channel estimation. The RX Chip/Rake Manager  308  may further be configured to decode transport channel control data, (transport format combination indicator (TFCI), HS-SCCH), indicator channels, (e.g. acquisition indicator channel (AICH), physical indicator channel (PICH), ICH), and High speed uplink packet access (HSUPA) Grant channels (E-AGCH, E-RGCH, E-HICH), and to compute feedback bits (feedback indicator (FBI), transmission power command (TPC), channel quality indicator (CQI)) to be transmitted on the uplink. The demodulated data may be provided to Rx Frame HW module  336  through SMA  320  memory. The Rx Chip/Rake Manager  308  may be configured to control hardware accelerators  330 - 335 . The Rx Chip/Rake Manager  308  may be configured to allocate and de-allocate fingers of the Rake. The Rx Chip/Rake Manager  308  may allocate Rake fingers to a cell for a path at a particular location (time delay) when the Path Searcher  331  reports the presence of a high-quality path that does not already have a Rake finger allocated to that path. Once initiated, the Rake module  335  may autonomously track the path as its location changes over time, periodically reporting the updated location and signal quality of the path to the Rx Chip/Rake Manager  308 . The Rx Chip/Rake Manager  308  may de-allocate allocated Rake fingers when the signal quality reported by the Rake finger sufficiently degrades (however, the Rx Chip/Rake Manager  308  may not drop fingers that are experiencing only relatively short fades) or are reallocated to stronger paths (and possibly to other cells). The Rx Chip/Rake Manager  308  may also be configured to detect the case of finger collision and either drop one of the two colliding fingers or organizes colliding fingers into clusters. 
     The Rake module  335  may be configured to demodulate data from the physical channels for dedicated, common, and shared type channels. The RX Chip/Rake manager  308  may comprise an alignment buffer for alignment of paths from the serving cell as well as from other Node-Bs in an active set and neighbor cells for measurement purposes. The Rake module  335  may perform de-scrambling and detection for multiple channelization codes. 
     The CE-NLMS equalizer  334  may be configured to mitigate multipath interference that may be introduced by the channel. The CE-NLMS equalizer  334  may comprise an adaptive finite impulse response (FIR) filter where the adaptation process is based on a CE-NLMS algorithm. The CE-NLMS algorithm is based on the standard LMS algorithm with a modification that is designed to combat gradient noise amplification when the magnitude of the input vector is large. The CE-NLMS equalizer  334  may be configured to support WTRU receiver diversity and Node-B transmit diversity. The CE-NLMS equalizer  334  may be configured to operate on the HS-DPDCH and HS-SCCH channels. 
     The ICH module  330  may be configured to detect the E-RGCH, E-HICH, AICH, PICH, and MICH channels. For the E-RGCH, the radio links in the E-DCH serving radio link set may be soft combined. For the E-HICH, for each Radio Link Set (RLS), all the radio links may be soft combined. The ICH module  330  may comprise shared hardware to support detection of these channels. 
     The Path Searcher  331  may be configured to detect path (multipath) locations and signal the path locations together with metrics indicating the normalized average magnitude to the Rx Chip/Rake Manager  308 . The Rx Chip/Rake Manager  308  may be configured to receive the path location information and assign Rake fingers to new paths. 
     The HS-SCCH/AGCH decoder  332  may be configured to perform decoding of the HS-SCCH channel. The HS-SCCH/AGCH decoder  332  may be reused for R6 upgrades to receive input from the Rake module  335  and demodulate the HSUPA DL E-AGCH channel. 
     The L1 Feedback module  333  may be configured to generate information that a Node-B may require from uplink channels to achieve certain link adaptation. For example, the information may comprise a downlink power control command, which is represented in TPC bits of uplink DPCCH; information for antenna weights, which is represented in the D field of FBI bits of an uplink DPCCH, that may be applied at the Node-B antennas when closed loop transmit diversity is applied; and channel quality, which may be represented in CQI bits of the uplink HS-DPCCH channel. In case of the closed loop transmit diversity (CLTD) mode, the L1 Feedback module  333  may also be configured to generate antenna weights that may be used for combining complex gains estimated by the Rake finger locations. 
     The Rx Frame HW module  336  and the Rx Frame SW  307  may be referred to collectively as the Rx Frame component. The Rx Frame HW module  336  may be configured to decode and de-multiplex the Coded Composite Transport Channel (CCTrCH), and process transport channels including Dedicated Channel (DCH), Broadcast Channel (BCH), Forward Access Channel (FACH), and the Paging Channel (PCH). The Rx Frame HW module  336  contains a high speed path (for HSDPA) and a regular speed path for DCH channels. The high speed path may be reused to support MBMS channels. 
     The Layer 1 Manager and Scheduler  302  may comprise a management and schedule entity. The management entity of the Layer 1 Manager and Scheduler  302  may be configured to perform control and status messaging to/from the higher layers (L2/3), and to indicate data availability, (e.g. data available in the SMA  320 ). The management entity may also comprise a layer 1 state machine. The scheduling entity of the Layer 1 Manager and Scheduler  302  may be configured to initiate the Layer 1 module functionality at the appropriate time and rate (e.g. slot rate scheduling, frame rate scheduling, etc.). The scheduling entity may also be configured to handle interrupts from the Layer 1 hardware and evaluate the cause of the interrupt to determine a next action. The Layer 1 Manager and Scheduler  302  may further be configured to perform power management of the Layer 1 subsystem by deciding which power islands may be enabled in which state, as will be discussed in greater detail hereafter. Power management may be used to reduce power in both active data and sleep states. 
     The PE  321  and DSMA  322  subsystem may be configured to provide Layer 2/3 hardware acceleration for modem transmit and receive operations. In one embodiment, the modem  122  may include three PEs  321 , each comprising a Dedicated Programmable Controller (DPC) and a specialized data path, but quantity may be scaled to support other data rates. The DPC may be programmable to operate on multiple channel types (e.g., HSDPA, HSUPA, DCH, and MBMS) and dynamically switch between processing of each type. The PE  321  data path may interface with the SMA  320  through an SMA Interface node, and the SDRAM  340  through a DSMA interface node. The DSMA  322  may be configured to provide access for multiple modules within the modem to the external SDRAM subsystem  340 . Each PE  321  may be configured to perform data movement, including the ability to gather data from various locations, perform bit alignment, and merge to a destination. Each PE  321  may also perform header interpretation, through the use of stream extract functionality. Each PE  321  may also perform header generation, through the use of cipher insert functionality. Each PE  321  may also perform cipher/de-cipher processing during data movement (when the ciphering engine option is enabled). Each PE  321  may also move data from SMA  320  to SDRAM  340  in downlink processing and move data from SDRAM  340  to SMA  320  in uplink processing 
     The Layer 1 Debug Agent  306  may be configured to provide a serial interface (USIF)  339  to an external processor. The processor  115  may transmit diagnostic data through the USIF module  339 . 
     The Layer 2/3 Protocol Stack module  301  may be configured to perform Radio Resource Control, Medium Access Control, Radio Link control, and Packet Data Convergence Protocol (PDCP) procedures. The Layer 2/3 Protocol Stack module  301  may also be configured to perform Non-Access Stratum procedures. 
     The Memory Controller  323  may be configured to connect on-chip controller cores, e.g., host processor, to a wide variety of external resources such as memories and peripherals, and allow flexible programming of the access parameters. The Memory Controller  323  may provide an Intel-style peripheral/device support and multiplexed access on the same bus. A plurality of memory devices may be connected to a host processor via one memory controller instance of an external bus unit. 
       FIG. 5  shows data flow for downlink data. Rx chip data is received in subframes or frames. The subframes or frames are demodulated into soft symbols and sent to the SMA, The SMA forwards the data to the Rx composite module, wherein the composite channels are then decomposed, de-ratematching, and de-interleaving are performed. The decomposed composite channels are then forwarded to the SMA. The SMA then forwards the data to the PE wherein the signal is then decoded, and CRC check is performed. The data may then be deciphered (if ciphering is enabled). The Headers are then stripped and PDU data is shifted from SMA to SDRAM. The PE then receives the data again and reorders and concatenates the data segments. If Point-to-Point Protocol (PPP) is being used, the data may be passed through a PPP Assist block, the PPP block may be configured to provide hardware support for some of the low-level functions required for PPP. The function of the PPP block may include byte stuffing, etc. If a “per bye” IO is needed, the signal may be passed through an Service Information Octet (SIO) assist module. The SIO assist module may be configured to handle low level interface between an application and the modem. In many cases this means that individual bytes must be manipulated. For example, many applications want to view the modem as though it is a Universal Asynchronous Receiver and Transmitter (UART). The SIO assist module may provide byte-to-word (word-to-byte) assist, monitor for access terminal command escape sequences, handle low level interface (i.e. USB) details, etc. These simple hardware assist functions may reduce the load on the main control processor. 
       FIG. 6  shows data flow for uplink data. Transport block sets (resident in SMA) are partitioned (when necessary). The Tx Frame component may attach CRCs, encode data, perform rate matching and interleave the signal. The resulting channel coded data is placed back into the SMA  320  (each radio frame or subframe). The Tx Chip component pulls encoded data from the SMA  320 , applies the appropriate scrambling code, spreads the data, etc. with the resulting data being streamed to the RF block (via the DFE HW module  326 ). As noted above, a PPP assist module and an SIO assist module may also be used in this procedure. 
       FIGS. 7A and 7B  show a modem partitioned into different power domains to achieve more effective power management and power conservation. The modem  122  may be partitioned into discrete power domains called power islands. The partitioning may be based on functionality.  FIGS. 7A and 7B  include six power domains including a Left ARM island  701 , a Base Island  702 , an R4 Chip Island  703 , an R4 Frame island  704 , an HSPA Island  705 , and a Stand-By Domain  706 . While six power domains are shown, more or less power domains may be used based on the embodiment. The processor  115  may be configured to turn on each power domain only when its associated functionality is desired. 
     Referring to the power islands of  FIGS. 7A and 7B , power management may be performed based on the operating mode of the modem. In a sleep mode, all power domains can be shut off during periods when no functionality is desired. The Sleep Timer  328 , which runs off of a low-frequency crystal, may remain continuously powered. The processor  115  may be configured to program when the Sleep Timer  328  will turn off the other power domains and it may program the length of time the Sleep Timer  328  may wait before turning the power domains back on (wake-up). At each wake-up event, the Timing Manager  327  may resynchronize any timing manager counters. If no activity is required, sleep can be re-initiated. In one embodiment, the memories may remain powered on in low retention modes during sleep mode. 
     In Deep Sleep Mode, during long periods inactivity, (where synchronization of the timing manager  327  counter is not required), the modem  122  may be configured to remain a reset state. This may be performed by asserting a reset pin. During Deep Sleep mode all power islands may be powered off. A Wake-up procedure is not activated until the reset pin is de-asserted. After a reset, the modem  122  may be re-booted from an image that is already loaded in the processor&#39;s  115  TCM memories. Thus avoiding the need for a complete re-boot. 
     For Active Mode/Coarse Clock Gating, the hardware accelerators  119  may be partitioned into discrete clock domains. Each discrete clock domain may be enabled/disabled by the processor  115 , a hardware accelerator  119 , or both. Each discrete clock domain may be turned on only when its associated functionality is desired. Hardware accelerators may autonomously gate their clocks (i.e. turn off) at completion of their scheduled process. 
     In another embodiment, in order to reduce the hardware, various components that are commonly used in a UMTS modem may be shared or reused during various modem operating modes. The components that are shared may include, for example, a High Speed-Shared Control Channel (HS-SCCH) decoder for HS-SCCH decoding and Enhanced Dedicated Channel (E-DCH) Absolute Grant Channel (E-AGCH) decoding; a Rake Annex which handles the E-DCH HARQ Acknowledgement Indicator Channel (E-HICH), E-DCH Relative Grant Channel (E-RGCH) and E-AGCH and Multimedia Broadcast Multicast Service (MBMS); a Low Speed Frame Processing which handles R4 and MBMS; High Speed Frame Processing for High Speed Downlink Packet Access (HSDPA) and MBMS; an IR Buffer for HSDPA and MBMS; a Protocol Engine for HSDPA/High Speed Uplink Packet Access (HSUPA)/DCH/MBMS; L1 Feedback (Continuous Quality Improvement (CQI) and Transmit Power Control (TPC) generation) (Common Signal to Interference Ratio (SIR) estimator), and/or ICH (MICH/PICH/AICH). 
     Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements. The methods or flow charts provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). 
     Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine. 
     A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated (FM) radio unit, a liquid crystal display (LCD) display unit, an organic light-emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB) module.