Patent Publication Number: US-2021185665-A1

Title: Methods and apparatus for providing a demapping system to demap uplink transmissions

Description:
CLAIM TO PRIORITY 
     This application is a divisional of a US patent application having a Ser. No. 16/404,029 filed on May 6, 2019, entitled “Methods and Apparatus for Providing A Demapping System to Demap Uplink Transmissions,” which further claims priority from U.S. Provisional Application No. 62/667,215, filed on May 4, 2018, and entitled “METHOD AND APPARATUS FOR PROVIDING A SAMPLE SINGLE-SHOT PROCESSING SCHEME FOR DATA TRANSMISSION.” All mentioned U.S. patents and/or applications are hereby incorporated by reference. 
    
    
     FIELD 
     The exemplary embodiments of the present invention relates to telecommunications network. More specifically, the exemplary embodiments of the present invention relates to receiving and processing data streams using a wireless communication network. 
     BACKGROUND 
     With a rapidly growing trend of mobile and remote data access over a high-speed communication network such as Long Term Evolution (LTE), fourth generation (4G), fifth generation (5G) cellular services, accurately delivering and deciphering data streams become increasingly challenging and difficult. The high-speed communication network which is capable of delivering information includes, but not limited to, wireless network, cellular network, wireless personal area network (“WPAN”), wireless local area network (“WLAN”), wireless metropolitan area network (“MAN”), or the like. While WPAN can be Bluetooth or ZigBee, WLAN may be a Wi-Fi network in accordance with IEEE 802.11 WLAN standards. 
     In 5G systems, reference signals may be included in uplink transmissions. These signals are used to estimate channel conditions or for other purposes. However, these signals are mixed in with data so that the reference signals must be accounted for when the data is processed. For example, when processing data received in resource elements, special processing may be needed to skip over resource elements that contain the reference signals. Even if the reference signals are set to zero or empty, their resource elements still need to be accounted for when processing the data. 
     Therefore, it is desirable to have a system that can efficiently demap received uplink transmissions while overcoming the disadvantages of conventional systems. 
     SUMMARY 
     In various exemplary embodiments, methods and apparatus are provided for a demapping system that efficiently demaps 4G and 5G uplink transmissions. When a first type of processing is used, reference signals are removed from the received resource elements in an uplink transmission before layer demapping. After layer demapping, soft demapping is then performed prior to descrambling. When a second type of processing is used, the received resource elements are despread before the soft demapping process. In this second case, reference signal removal and layer demapping is bypassed. When a third type of processing is used, the received resource elements are input directly to the soft mapper and bypass the despreader. Thus, the demapping system operates to provide fast and resource efficient demapping of received uplink transmissions in 4G and 5G wireless networks. 
     In an embodiment, a method is provided that includes detecting a processing type associated with a received uplink transmission, and when the detected processing type is a first processing type then performing the following operations: removing resource elements containing reference signals from the uplink transmission; layer demapping remaining resource elements of the uplink transmission into two or more layers; soft-demapping the two or more layers to produce soft-demapped data. The method also comprises descrambling the soft-demapped data to produce descrambled data, and processing the descrambled data to generate uplink control information (UCI). 
     In an embodiment, an apparatus is provided that includes a detector that detects a processing type associated with a received uplink transmission, and a reference signal (RS) remover that removes resource elements containing reference signals from the uplink transmission, when the detected processing type is a first processing type. The apparatus also includes a layer demapper that demaps remaining resource elements of the uplink transmission into two or more layers, when the detected processing type is the first processing type, and a soft demapper that soft-demaps the two or more layers to produce soft-demapped bits, when the detected processing type is the first processing type. 
     Additional features and benefits of the exemplary embodiments of the present invention will become apparent from the detailed description, figures and claims set forth below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The exemplary aspects of the present invention will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the invention, which, however, should not be taken to limit the invention to the specific embodiments, but are for explanation and understanding only. 
         FIG. 1  shows a block diagram of a communication network in which uplink transmissions from user equipment are demapped by exemplary embodiments of a demapping system. 
         FIG. 2  shows an exemplary embodiment of a demapping system. 
         FIG. 3  shows an exemplary embodiment of a layer demapper for use in the demapping system shown in  FIG. 2 . 
         FIG. 4  shows an exemplary method for performing demapping in accordance with exemplary embodiments of a demapping system. 
         FIG. 5  is a block diagram illustrating a processing system having an exemplary embodiment of a demapping system. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the present invention are described herein the context of methods and apparatus for demapping data received in 5G uplink transmission. 
     The purpose of the following detailed description is to provide an understanding of one or more embodiments of the present invention. Those of ordinary skills in the art will realize that the following detailed description is illustrative only and is not intended to be in any way limiting. Other embodiments will readily suggest themselves to such skilled persons having the benefit of this disclosure and/or description. 
     In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be understood that in the development of any such actual implementation, numerous implementation-specific decisions may be made in order to achieve the developer&#39;s specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be understood that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skills in the art having the benefit of embodiments of this disclosure. 
     Various embodiments of the present invention illustrated in the drawings may not be drawn to scale. Rather, the dimensions of the various features may be expanded or reduced for clarity. In addition, some of the drawings may be simplified for clarity. Thus, the drawings may not depict all of the components of a given apparatus (e.g., device) or method. The same reference indicators will be used throughout the drawings and the following detailed description to refer to the same or like parts. 
     The term “system” or “device” is used generically herein to describe any number of components, elements, sub-systems, devices, packet switch elements, packet switches, access switches, routers, networks, modems, base stations, eNB (eNodeB), computer and/or communication devices or mechanisms, or combinations of components thereof. The term “computer” includes a processor, memory, and buses capable of executing instruction wherein the computer refers to one or a cluster of computers, personal computers, workstations, mainframes, or combinations of computers thereof. 
     IP communication network, IP network, or communication network means any type of network having an access network that is able to transmit data in a form of packets or cells, such as ATM (Asynchronous Transfer Mode) type, on a transport medium, for example, the TCP/IP or UDP/IP type. ATM cells are the result of decomposition (or segmentation) of packets of data, IP type, and those packets (here IP packets) comprise an IP header, a header specific to the transport medium (for example UDP or TCP) and payload data. The IP network may also include a satellite network, a DVB-RCS (Digital Video Broadcasting-Return Channel System) network, providing Internet access via satellite, or an SDMB (Satellite Digital Multimedia Broadcast) network, a terrestrial network, a cable (xDSL) network or a mobile or cellular network (GPRS/EDGE, or UMTS (where applicable of the MBMS (Multimedia Broadcast/Multicast Services) type, or the evolution of the UMTS known as LTE (Long Term Evolution), or DVB-H (Digital Video Broadcasting-Handhelds)), or a hybrid (satellite and terrestrial) network. 
       FIG. 1  shows a block diagram of a communication network  100  in which uplink transmissions from user equipment are demapped by exemplary embodiments of a demapping system (DS)  152 . The network  100  includes packet data network gateway (“P-GW”)  120 , two serving gateways (“S-GWs”)  121 - 122 , two base stations (or cell sites)  102 - 104 , server  124 , and Internet  150 . P-GW  120  includes various components  140 , such as billing module  142 , subscribing module  144 , and/or tracking module  146  to facilitate routing activities between sources and destinations. It should be noted that the underlying concept of the exemplary embodiments of the present invention would not change if one or more blocks (or devices) were added to or removed from diagram  100 . 
     The network configuration  100  may also be referred to as a fourth generation (“4G”), Long Term Evolution (LTE), Fifth Generation (5G), New Radio (NR) or combination of 4G and 5G cellular network configurations. Mobility Management Entity (MME)  126 , in one aspect, is coupled to base stations (or cell site) and S-GWs capable of facilitating data transfer between 4G LTE and 5G. MME  126  performs various controlling/managing functions, network securities, and resource allocations. 
     S-GW  121  or  122 , in one example, coupled to P-GW  120 , MME  126 , and base stations  102  or  104 , is capable of routing data packets from base station  102 , or eNodeB, to P-GW  120  and/or MME  126 . A function of S-GW  121  or  122  is to perform an anchoring function for mobility between 3G and 4G equipments. S-GW  122  is also able to perform various network management functions, such as terminating paths, paging idle UEs, storing data, routing information, generating replica, and the like. 
     P-GW  120 , coupled to S-GWs  121 - 122  and Internet  150 , is able to provide network communication between user equipment (“UE”) and IP based networks such as Internet  150 . P-GW  120  is used for connectivity, packet filtering, inspection, data usage, billing, or PCRF (policy and charging rules function) enforcement, et cetera. P-GW  120  also provides an anchoring function for mobility between 4G and 5G packet core networks. 
     Base station  102  or  104 , also known as cell site, node B, or eNodeB, includes one or more radio towers  110  or  112 . Radio tower  110  or  112  is further coupled to various UEs, such as a cellular phone  106 , a handheld device  108 , tablets and/or iPad®  107  via wireless communications or channels  137 - 139 . Devices  106 - 108  can be portable devices or mobile devices, such as iPhone®, BlackBerry®, Android®, and so on. Base station  102  facilitates network communication between mobile devices such as UEs  106 - 107  with S-GW  121  via radio towers  110 . It should be noted that base station or cell site can include additional radio towers as well as other land switching circuitry. 
     To improve efficiency and/or speed-up extracting uplink control information received from any of the user equipment, a demapping system  152  is provided that operates according to one of three processing types. When a first type of processing is used, reference signals are removed from the received resource elements of an uplink transmission before layer demapping. After layer demapping is completed, soft demapping is then performed prior to descrambling. When a second type of processing is used, the received resource elements are despread before the soft demapping process. In this second case, reference signal removal and layer demapping is bypassed. In a third processing type, the received resource elements bypass RE removal, layer demapping and despreading and are input directly to a soft demapper. A more detailed description of the demapping system  152  is provided below. 
       FIG. 2  shows an exemplary detailed embodiment of the demapping system  152  shown in  FIG. 1 .  FIG. 2  shows user equipment (“UE”)  224  having antenna  222  that allows wireless communication with base station  112  through wireless transmissions  226 . The UE  224  transmits uplink communications  230  that are received by base station front end (FE)  228 . In an embodiment, the base station includes gain normalizer  202 , inverse transform block (IDFT)  204 , configuration parameters  222 , the demapping system  152 , descrambler  218  and combiner/extractor  220 . In an exemplary embodiment, the demapping system  152  includes processing detector  208 , RS (reference signal or symbol) remover  210 , layer demapper  212 , despreader  214 , and soft demapper  216 . The output of the soft demapper  216  is input to the descrambler  218  and its output is input to the combiner/extractor  220  that produces decoded UCI information. 
     In an embodiment, the demapping system  152  processes 1 symbol at a time, which may come from multiple layers for NR, and the demapping system  152  processes the whole subframe or slot of a layer for LTE covering 1 ms transmission time interval (TTI), 7-OFDM symbol (OS) short (s) TTI, and 2/3-OS sTTI. The modulation order can be derived as follows. 
     1. (π/2) BPSK for NR 
     2. (π/2) BPSK for LTE sub-PRB, QPSK, 16QAM, 64QAM, and 256QAM 
     Furthermore, demapping rules apply to constellations as defined in LTE (4G) and/or NR (5G) standards. 
     Configuration Parameters (Block  222 ) 
     In an embodiment, the configuration parameters  222  comprise multiple fields that contain parameters for use by multiple blocks shown in  FIG. 2 . For example, some of the configuration parameters  222  control the operation of the gain normalizer  202 , IDFT  204  and demapping system  152 . In an embodiment, the configuration parameters  222  may indicate that the gain normalizer  202  and the IDFT  204  are to be bypassed. 
     Gain Normalizer (Block  202 ) 
     In an embodiment, the gain normalizer  202  performs a gain normalization function on the received uplink transmission. For example, the gain normalizer  202  is applicable to LTE and NR DFT-s-OFDM cases. Input samples will be normalized as follows per data symbol per subcarrier with a norm gain value calculated per symbol as follows. 
       Gainnorm_out[ Ds ][ sc ]=(Gainnorm_in[ Ds ][ sc ])/(Norm_Gain[ Ds ]) 
     IDFT (Block  204 ) 
     The IDFT  204  operates to provide an inverse transform to generate time domain signals. In an embodiment, the IDFT  204  is enabled only for LTE and NR DFT-s-OFDM and LTE sub-PRB. In an embodiment, the inputs and outputs are assumed to be 16 bits I and Q values, respectively. The DFT and IDFT operations are defined as follows. 
     
       
         
           
             
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     Processing Type Detector (Block  208 ) 
     In exemplary embodiments, the processing type detector  214  detects the type of processing to be performed by the system. For example, this information may be detected from the configuration parameters  222 . In an embodiment, the processing type detector  208  operates to detect one of three processing types, which cover the operation of the system as follows. 
     1. Type 1-5G NR DFT-s-OFDM 
     2. Type 1-5G NR CP-OFDM 
     3. Type 2-5G NR PUCCH Format 4 
     4. Type 3-4G LTE DFT-s-OFDM 
     5. Type 3-4G LTE sub-PRB allocation 
     RS Remover (Block  210 ) 
     In an embodiment, the RS remover  210  operates during Type 1 processing to remove RS resource elements from the received data stream to produce a stream of data that is input to the layer demapper. For example, the RE locations of the RS symbols are identified and the data is re-written into one or more buffers to remove the RS symbols to produce an output that contains only data. In an embodiment, Type 1 processing includes RS/DTX removal, layer demapping with an interleaving structure, soft demapping, and descrambling. A benefit of removal of RS before layering is to operate a single shot descrambling without any disturbance in a continuous fashion with no extra buffering. 
     Layer Demapper (Block  212 ) 
       FIG. 3  shows an exemplary embodiment of layer demapper  212 . In an embodiment, Data and signal to interference noise ratio (SINR) coming from multiple layers Data(L0-L3) and SINR(L0-L3) of a certain subcarrier will be transferred into a layer demapping circuit  304  via multi-threaded read DMA operation. In this case, each thread will point to the memory location of different layers for a certain symbol as shown in  FIG. 3 . The layer demapping circuit  304  produces demapped data and multiple SINR reports per layer. In an embodiment, for NR the DMRS/PTRS/DTX REs will be removed from the information stream prior to soft demapper both from I/Q and SINR samples. 
     Referring again to  FIG. 2 , additional blocks of the demapping system  152  are described in detail below. 
     Despreader (Block  214 ) 
     In an embodiment, the despreader  214  provides despreading for PUCCH Format 4 only. It consists of combining the repeated symbols along the frequency axis upon multiplying them with the conjugate of the proper spreading sequence. The spreading sequence index as well as the spreading type for combining the information in a correct way will be given by the configuration parameters  222 . This process is always performed over 12 REs in total. The number of REs that will be pushed into subsequent blocks will be reduced by half or ¼th after despreading depending upon the spreading type. Combined results will be averaged and stored as 16-bit before soft demapping. 
     Soft Demapper (Block  216 ) 
     The soft demapping principle is based on computing the log-likelihood ratio (LLR) of a bit that quantifies the level of certainty on whether it is logical zero or one. Under the assumption of Gaussian noise, LLR for the i-th bit is given by: 
     
       
         
           
             
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     where c j  and c k  are the constellation points for which i-th bit takes the value of 0 and 1, respectively. Note that for the gray mapped modulation schemes given in [R1], x may be taken to refer to a single dimension I or Q. Computation complexity increases linearly with the modulation order. A max-log MAP approximation has been adopted in order to reduce the computational complexity. Note that this approximation is not necessary for QPSK since its LLR has only one term on both numerator and denominator. 
     
       
         
           
             
               
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     This approximation is accurate enough especially in the high SNR region and simplifies the LLR calculation drastically avoiding the complex exponential and logarithmic operations. Given that I and Q are real and imaginary part of input samples, the soft LLR is defined as follows for (π/2) BPSK, QPSK, 16QAM, 64QAM, and 256QAM, respectively. 
     It should be noted that (π/2) BPSK is only applicable to NR DFT-s-OFDM and LTE sub-PRB cases. There are two flavors of this modulation format. For the first case, the constellation is shifted by (π/2) across subcarriers along the frequency axis. Hence, the demapper will change the demapping rule from subcarrier to subcarrier with the order specified below. For the other scenario, the demapping rule will stay the same along the frequency axis and soft demapper will always generate LLRs using the first rule specified below. This behavior of changing the LLR generation rule across frequencies or not will be controlled by a configuration parameter. 
     In an embodiment, the soft demapper  216  includes a first minimum function component (“MFC”), a second MFC, a special treatment component (“STC”), a subtractor, and/or an LLR generator. A function of soft demapper  216  is to demap or ascertain soft bit information associated to received symbols or bit streams. For example, soft demapper  216  employs soft demapping principle which is based on computing the log-likelihood ratio (LLR) of a bit that quantifies the level of certainty as to whether it is a logical zero or one. To reduce noise and interference, soft demapper  216  is also capable of discarding one or more unused constellation points relating to the frequency of the bit stream from the constellation map. 
     The STC, in one aspect, is configured to force an infinity value as one input to the first MFC when the stream of bits is identified and a special treatment is needed. For example, a predefined control signal with a specific set of encoding categories such as ACK with a set of predefined encoding categories requires a special treatment. One of the special treatments, in one aspect, is to force infinity values as inputs to MFCs. For example, STC force infinity values as inputs to the first and the second MFCs when the stream of bits is identified as ACK or RI with a predefined encoding category. The STC, in one instance, is configured to determine whether a special treatment (or special treatment function) is required based on received bit stream or symbols. In one aspect, the 1-bit and 2-bit control signals with predefined encoding categories listed in Table 1 require special treatments. It should be noted that Table 1 is exemplary and that other configurations are possible. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 No. 
                 Control Signal with Encoding Categories 
                 Renamed Categories 
               
               
                   
               
             
            
               
                 1 
                 O ACK  = 1 
                 ACK [1] 
               
               
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                 O ACK  = 1 ACK bundling 
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                 O ACK  = 2 ACK bundling 
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                 O RI  = 1 
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                 6 
                 O RI  = 2 
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     Table 1 illustrates six (6) exemplary control signals with predefined encoding categories. To simplify forgoing description, six (6) control signals are renamed or referred to as ACK [1], ACK[2], ACK[3], ACK[4], RI[1], and RI [2], respectively. For example, 1-bit ACK, “O ACK =1” is referred to as ACK[1] and 1-bit ACK bundling is referred to as ACK [2]. 2-bit ACK, “O ACK =2” is referred to as ACK[3] and 2-bit ACK bundling is referred to as ACK[3]. Similarly, 1-bit RI “O RI =1” is referred to as RI[1] and 2-bit RI “O RI =2” is referred to as RI [2]. Note that ACK [1] indicates that ACK control signal with one (1) bit to indicate its value and ACK [3] indicates that ACK control signal uses two (2) bits to indicate its value. ACK bundling reduces the number of ACKs to be transferred in TDD-LTE (Time Division Duplexing LTE) networks by a logical AND operation between the ACKs belonging to multiple downlink subframes. 
     Descrambler (Block  218 ) 
     The descrambler  218  is configured to generate a descrambling sequence of bits or a stream of bits. For example, after generating a sequence in accordance with the input value, the descrambler determines whether sequence modification is needed for certain categories of control information. The stream of bits or sequence is subsequently descrambled to produce a set of descrambled soft bits. 
     Combiner/Extractor (Block  220 ) 
     The combiner/extractor  220  provides a combining and extracting function to combine descrambled soft bits from the descrambler  218  and extract Uplink Control Information (“UCI”). 
       FIG. 4  shows an exemplary method  400  for performing demapping in accordance with exemplary embodiments of a demapping system. For example, the method  400  is suitable for use with the demapping system  152  shown in  FIG. 2 . In various exemplary embodiments, the method  400  operates to perform demapping operations for three processing types while reusing the same hardware of the demapping system  152 , thereby providing fast and efficient demapping of received 4G and 5G uplink transmissions. 
     At block  402 , uplink transmissions are received in a 4G/5G communication network. For example, the uplink communications are received at the front end  228  shown in  FIG. 2 . 
     At block  404 , gain normalization is performed. For example, the gain normalization is performed by the gain normalizer  202  shown in  FIG. 2 . 
     At block  406 , an inverse Fourier transform is performed to obtain time domain signals. For example, this process is performed by the IDFT block  204  shown in  FIG. 2 . 
     At block  408 , a determination is made as to a type of processing to be performed. For example, a description of three processing types is provided above. If a first type of processing is to be performed, the method proceeds to block  410 . If a second type of processing is to be performed, the method proceeds to block  420 . If a third type of processing is to be performed, the method proceeds to block  414 . For example, this operation is performed by the processing type detector  208  shown in  FIG. 2 . 
     At block  420 , when the processing type is Type 2, despreading is performed on the received resource elements. For example, this operation is performed by the despreader  214  shown in  FIG. 2 . The method then proceeds to block  414 . 
     When the processing type is Type 3, the method proceeds to block  414 . 
     When the processing type is Type 1, the follow operations are performed. 
     At block  410 , the reference signals are removed from the received resource elements. For example, resource elements containing RS/DTX are removed. This operation is performed by the RS remover  210  shown in  FIG. 2 . 
     At block  412 , layer demapping is performed. For example, the resource elements without RS/DTX are layer demapped. This operation is performed by the layer demapper  212 . 
     At block  414 , soft demapping is performed. For example, the soft demapper  216  soft-demaps bits for each processing type. During processing Type 3, the soft demapper  216  receives the resource elements and soft demaps these bits to produce a soft-demapped output. During processing Type 2, the soft demapper  216  receives the despread bits from the despreader  214  and soft demaps these bits to produce a soft-demapped output. During processing Type 1, the soft demapper  216  receives the layer demapped bits from the layer demapper  212  and soft demaps these bits to produce a soft-demapped output. 
     At block  416 , descrambling is performed. For example, the descrambler  218  receives the soft demapped bits from the soft demapper  216  and generates descrambled bits. 
     At block  418 , combining and extraction of UCI information is performed. For example, the combiner/extractor  220  receives the descrambled bits, combines these bits, and extracts the UCI information. 
     Thus, the method  400  operates to provide demapping in accordance with the exemplary embodiments. It should be noted that the operations of the method  400  can be modified, added to, deleted, rearranged, or otherwise changed within the scope of the embodiments. 
       FIG. 5  is a block diagram illustrating a processing system  500  having an exemplary embodiment of a demapping system  530 . It will be apparent to those of ordinary skill in the art that other alternative computer system architectures may also be employed. 
     The system  500  includes a processing unit  501 , an interface bus  512 , and an input/output (“IO”) unit  520 . Processing unit  501  includes a processor  502 , main memory  504 , system bus  511 , static memory device  506 , bus control unit  505 , and mass storage memory  508 . Bus  511  is used to transmit information between various components and processor  502  for data processing. Processor  502  may be any of a wide variety of general-purpose processors, embedded processors, or microprocessors such as ARM® embedded processors, Intel® Core™2 Duo, Core™2 Quad, Xeon®, Pentium™ microprocessor, AMD® family processors, MIPS® embedded processors, or Power PC™ microprocessor. 
     Main memory  504 , which may include multiple levels of cache memories, stores frequently used data and instructions. Main memory  504  may be RAM (random access memory), MRAM (magnetic RAM), or flash memory. Static memory  506  may be a ROM (read-only memory), which is coupled to bus  511 , for storing static information and/or instructions. Bus control unit  505  is coupled to buses  511 - 512  and controls which component, such as main memory  504  or processor  502 , can use the bus. Mass storage memory  508  may be a magnetic disk, solid-state drive (“SSD”), optical disk, hard disk drive, floppy disk, CD-ROM, and/or flash memories for storing large amounts of data. 
     I/O unit  520 , in one example, includes a display  521 , keyboard  522 , cursor control device  523 , decoder  524 , and communication device  525 . Display device  521  may be a liquid crystal device, flat panel monitor, cathode ray tube (“CRT”), touch-screen display, or other suitable display device. Display  521  projects or displays graphical images or windows. Keyboard  522  can be a conventional alphanumeric input device for communicating information between computer system  500  and computer operators. Another type of user input device is cursor control device  523 , such as a mouse, touch mouse, trackball, or other type of cursor for communicating information between system  500  and users. 
     Communication device  525  is coupled to bus  512  for accessing information from remote computers or servers through wide-area network. Communication device  525  may include a modem, a router, or a network interface device, or other similar devices that facilitate communication between computer  500  and the network. In one aspect, communication device  525  is configured to perform wireless functions. Alternatively, demapping system  530  and communication device  525  perform the demapping functions in accordance with one embodiment of the present invention. 
     The demapping system  530 , in one aspect, is coupled to bus  511  and is configured to demap received uplink communications as described above to improve overall receiver performance. The demapping system  530  comprises hardware, firmware, or a combination of hardware and firmware. 
     While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from this exemplary embodiments of the present invention and its broader aspects. Therefore, the appended claims are intended to encompass within their scope all such changes and modifications as are within the true spirit and scope of this exemplary embodiments of the present invention.