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Method and system for improving dynamic range for communication systems using upstream analog informationRelated Patent Categories: Multiplex Communications, Pathfinding Or Routing, Switching A Message Which Includes An Address Header, Having A Plurality Of Nodes Performing Distributed Switching, Bridge Or Gateway Between NetworksMethod and system for improving dynamic range for communication systems using upstream analog information description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080008198, Method and system for improving dynamic range for communication systems using upstream analog information. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE [0001] This application is a continuation of U.S. patent application Ser. No. 10/810,405 filed Mar. 26, 2004, which makes reference to, claims priority to, and claims the benefit of U.S. Provisional Application Ser. No. 60/551,267 filed Mar. 8, 2004. [0002] The above stated application is hereby incorporated herein by reference in its entirety. FIELD OF THE INVENTION [0003] Certain embodiments of the invention relate to packet based wireless communication systems. More specifically, certain embodiments of the invention relate to a method and system for improving dynamic range for communication systems such as 802.11 systems using upstream analog information. BACKGROUND OF THE INVENTION [0004] In packet-based wireless communication systems, a transmitted packet may be received with a large range of signal strengths, that is, a wide dynamic range. For example, in an 802.11 system, there may be as much as a 100 dB difference in signal strength between packets received at receiver A sent from transmitter B versus a packet received by receiver A sent from transmitter C. Factors accounting for this variation include path loss and fading characteristics of a RF propagation channel, for example. Path loss may include attenuation losses incurred due to the distance existing between a transmitter and a receiver. Fading characteristics of the RF propagation channel may include multipath interference destructively combining to reduce the strength of the signal received at the receiver. A well-designed communication transceiver must perform reliably given these impairments that are characteristic of wireless media. In this regard, a goal of a well-designed communication transceiver is to mitigate these characteristic impairments. In order to achieve this goal, a practical receiver may make use of automatic gain control (AGC). Automatic gain control can be described as an algorithm that may be adapted to automatically adjust signal size in order to maximize some parameter. [0005] FIG. 1 is a block diagram of a conventional receiver system that utilizes gain control. Referring to FIG. 1, the conventional receiver comprises a mixer 102, a gain block 104, analog-to-digital converter (ADC) 106 and gain control block 108. The conventional receiver may be part of a packet-based wireless system, which is adapted to receive a signal that is transmitted at a particular carrier frequency. [0006] In operation, the mixer 102 receives an input received signal and mixes the received signal with a tuning frequency to generate a baseband signal. The gain block 104 applies an initial gain G.sub.initial to the baseband signal, and the AGC algorithm will apply a final gain output gain G.sub.final to the data portion of the packet. The analog to digital converter (ADC) 106 converts the analog signal to digital samples, which are subsequently processed. [0007] A good AGC algorithm that may be implemented in the gain block 108, is adapted to choose or provide a final gain value G.sub.final dB to apply to the data portion of the packet such that the signal to quantization noise ratio out of the ADC is maximized. Additionally, the final gain value G.sub.final dB is chosen so that it is not too large as to cause an overflow to occur at the ADC during reception of the packet. The first criterion maximizes the signal to quantization noise ratio (SQNR) for the packet, and the second criterion prevents the packet from almost certainly being received with errors due to signal distortion. A well-designed gain block 108 is configured to execute an AGC algorithm that will accomplish this task. [0008] Referring to FIG. 1, in L.sub.1 and L.sub.2 represents the limits of the ADC 106. In case 1, G.sub.final is too small and the resulting analog signal, which is an input to the ADC 106, does not optimally utilize the limits L.sub.1 and L.sub.2 of the ADC 106. Accordingly, the AGC algorithm would have made a poor decision or choice. In case 2, G.sub.final is too large and the resulting analog signal, which is an input to the ADC 106, does not optimally utilize the limits L.sub.1 and L.sub.2 since these limits of the ADC 106 are exceeded. Since the limits L.sub.1, L.sub.2 of the ADC are exceeded, clipping of the signal occurs. Accordingly, the AGC algorithm would have made a poor decision or choice. In case 3, G.sub.final is ideal and the resulting analog signal, which is an input to the ADC 106, optimally utilizes the limits L.sub.1 and L.sub.2 Of the ADC 106. In this case, no clipping of the analog signal occurs. Accordingly, the AGC algorithm would have made an ideal decision or choice. [0009] For 802.11 orthogonal frequency division multiplexing (OFDM) systems, the gain G.sub.final is calculated and applied during the preamble portion of the packet. The preamble of the packet is relatively short in time compared to the overall packet length, and corrections for other system impairments such as frequency offset may also need to be calculated during this portion of the transmission. Thus, the amount of time needed to determine the proper gain setting for the received packet needs to be kept small. For a practical 802.11a/g orthogonal frequency division multiplexing system, this means it is likely at most one intermediate gain setting G.sub.intermediate is allowed during the preamble to determine the final gain G.sub.final. [0010] FIG. 2 is a diagram illustrating the application of gain to a packet. Referring to FIG. 2, there is shown a packet 200 having a preamble portion 202 and a data portion 204. The leftmost portion of the packet 200 is the demarcation of the start of packet (SOP) and the rightmost portion of the packet 200 is the demarcation of the end-of-packet EOP. The gain G.sub.final is applied at reference A, which occurs during the preamble portion 202 of the packet 200. In this case, G.sub.final is greater than G.sub.initial (G.sub.final>G.sub.initial). [0011] FIG. 3 is a diagram illustrating the application of gain to a packet. Referring to FIG. 3, there is shown a packet 300 having a preamble portion 302 and a data portion 304. The leftmost portion of the packet 300 is the demarcation of the start of packet (SOP) and the rightmost portion of the packet 300 is the demarcation of the end-of-packet EOP. A gain G.sub.initial is in effect at the start-of-packet (SOP) where clipping is occurring. A gain G.sub.intermediate is applied at reference B where no clipping occurs but the signal is too small. A gain G.sub.final is applied at reference C where no clipping occurs and the signal is ideal. In this case, G.sub.initial, G.sub.intermediate and G.sub.final are applied during the preamble. [0012] In order for a receiver to detect small receiver signal input, the initial front-end gain G.sub.initial must necessarily be set to a large value. However, if the incoming signal is in fact large, the signal level at the output of the ADC will be clipped, making it difficult to determine the received signal power. That is, if a received signal power of X dBm is enough to cause a clip at the ADC, then all received signal powers greater than X dBm also cause a clip. [0013] Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings. BRIEF SUMMARY OF THE INVENTION [0014] Certain embodiments of the invention may be found in a method and system for improving dynamic range using upstream analog information. Aspects of the method may comprise generating a plurality of upstream analog signals for a received signal. Upstream analog information related to at least a portion of the generated plurality of upstream analog signals may be acquired. A gain for the received signal may be adjusted using at least a portion of the acquired upstream analog information to increase dynamic range of the received signal. [0015] The received signal is low pass filtered to generate a plurality of narrowband analog signals. At least one sample may be acquired from at least a portion of the generated plurality of upstream analog signals and a power for the received signal may be computed based on the acquired sample or samples. A determination may be made as to whether the generated plurality of upstream analog signals is clipped. An intermediate gain may be generated based on the computed power of the acquired sample and applied to one or more of the generated plurality of upstream analog signals if the signal is clipped. The computed power may be compared to a plurality of defined power values and a gain selected based on the comparison. The defined power values may be stored in lookup table, for example. A final gain may be applied to the received signal. The generated plurality of upstream analog signals may be converted to corresponding time domain signals. [0016] Another embodiment of the invention may provide a machine-readable storage, having stored thereon, a computer program having at least one code section executable by a machine, thereby causing the machine to perform the steps as described above for processing received signals in a communication system. [0017] Another embodiment of the invention provides a system for processing received signals. Aspects of the system may comprise a receiver that generates a plurality of upstream analog signals for a received signal. The generated plurality of upstream analog signals may be narrowband analog signals. At least one processor may acquire upstream analog information related to at least a portion of the generated plurality of upstream analog signals. At least one automatic gain controller may be adapted to adjust a gain for the received signal using at least a portion of the acquired upstream analog information to increase a dynamic range of the received signal. [0018] The system may further comprise at least one low pass filter that filters the received signal. The processor may acquire at least one sample from at least a portion the generated plurality of upstream analog signals and compute a power based on the acquired sample. The processor may be adapted to determine when at least one of the generated plurality of upstream analog signal is clipped. The automatic gain controller may generate an intermediate gain based on the computed power of the acquired sample. The processor may apply the generated intermediate gain to the generated plurality of upstream analog signals. After comparing the computed power to a plurality of defined power values, which may be stored in a lookup table, the processor may select a gain based on a comparable power value. The automatic gain controller may be utilized to apply a final gain to the received packet. The receiver may be adapted to convert the generated plurality of upstream analog signals to corresponding time domain signals. [0019] Another embodiment of the invention provides a receiver for processing received communication signals. The receiver may comprise a mixer, a low pass filter coupled to the mixer and a plurality of gain block serially coupled to an output of the low pass filter. The system may also comprise a plurality of analog to digital converters, wherein an input of a first of the analog-to-digital converters is coupled to the output of the low pass filter. An input of each of a remaining portion of the analog-to-digital converters is individually coupled to a corresponding output of each of the serially coupled gain blocks. An output path traced from the output of the low pass filter to an output of each of the analog-to-digital converters may be referred to as a processing path. Accordingly, each of the processing paths may comprise a gain controller and an analog to digital converter, except for the first processing path, which may have an ADC coupled directly to the output of the low pass filter. [0020] These and other advantages, aspects and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings. 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