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  Decoding using walsh space informationUSPTO Application #: 20060239182Title: Decoding using walsh space information Abstract: Methods and apparatus to improve the speed and reliability of decoders are presented herein. Namely, a priori knowledge of Walsh space information is used to increase the speed at which messages are decoded. In systems where control messages contain transmission parameters of concurrently transmitted packet data, a faster demodulation and decoding of control messages allows a receiver to demodulate the packet data sooner, so that a shorter buffer is needed to store the received packet data. The receiver uses the Walsh space from the previous successfully decoded message to first decode the current message. If the decoding attempt is unsuccessful, the receiver then uses a neighboring Walsh space to decode the current message. (end of abstract) Agent: Qualcomm Incorporated - San Diego, CA, US Inventor: Stein A. Lundby USPTO Applicaton #: 20060239182 - Class: 370209000 (USPTO) Related Patent Categories: Multiplex Communications, Generalized Orthogonal Or Special Mathematical Techniques, Particular Set Of Orthogonal Functions, Walsh Functions The Patent Description & Claims data below is from USPTO Patent Application 20060239182. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The present Application for Patent is a Continuation of patent application Ser. No. 10/027,637 entitled "Improved Decoding Using Walsh Space Information" filed Dec. 21, 2001, pending, and assigned to the assignee hereof and hereby expressly incorporated by reference herein. BACKGROUND [0002] 1. Field [0003] The present invention relates generally to communications, and more specifically, to decoding signals received on wireless communication systems. [0004] 2. Background [0005] The field of wireless communications has many applications including, e.g., cordless telephones, paging, wireless local loops, personal digital assistants (PDAs), Internet telephony, and satellite communication systems. A particularly important application is cellular telephone systems for mobile subscribers. As used herein, the term "cellular" system encompasses both cellular and personal communications services (PCS) frequencies. Various over-the-air interfaces have been developed for such cellular telephone systems including, e.g., frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). In connection therewith, various domestic and international standards have been established including, e.g., Advanced Mobile Phone Service (AMPS), Global System for Mobile (GSM), and Interim Standard 95 (IS-95). IS-95 and its derivatives, IS-95A, IS-95B, ANSI J-STD-008 (often referred to collectively herein as IS-95), and proposed high-data-rate systems are promulgated by the Telecommunication Industry Association (TIA) and other well known standards bodies. [0006] Cellular telephone systems configured in accordance with the use of the IS-95 standard employ CDMA signal processing techniques to provide highly efficient and robust cellular telephone service. Exemplary cellular telephone systems configured substantially in accordance with the use of the IS-95 standard are described in U.S. Pat. Nos. 5,103,459 and 4,901,307, which are assigned to the assignee of the present invention and incorporated by reference herein. An exemplary system utilizing CDMA techniques is the cdma2000ITU-R Radio Transmission Technology (RTT) Candidate Submission (referred to herein as cdma2000), issued by the TIA. The standard for cdma2000 is given in the draft versions of IS-2000 and has been approved by the TIA, and the 3rd Generation Partnership Project 2 "3GPP2". Another CDMA standard is the W-CDMA standard, as embodied in 3rd Generation Partnership Project "3GPP", Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214. [0007] The telecommunication standards cited above are examples of only some of the various communications systems that can be implemented. Within these various communications systems, multiple users must share limited system resources. In accordance with the actual system implementation, resources such as frequency bandwidth, time, transmission power, or spreading code assignments are typically shared by multiple users within the system. In a FDMA system, the system bandwidth is divided into many frequency channels and each frequency channel is allocated to a user. In a TDMA system, the system bandwidth is divided into many time slots and each time slot is allocated to a user. In a CDMA system, the system bandwidth is simultaneously shared among all users by using spreading codes, wherein each user is assigned a spreading code. [0008] User demand drives the development of higher transmission data rate systems. In systems that can transmit data traffic in packetized formats, such as TDMA and CDMA systems, control information is transmitted containing essential information, such as the identity of the addressee, the modulation format, the coding format, the transmission timing, and the orthogonal codes used to cover the data. Receivers that cannot decode this control information correctly will fail to receive the packet data. Furthermore, receivers that cannot decode this information in a timely manner will have to store portions or all of the possible orthogonal codes with sufficient resolution in a memory element, whereupon the stored codes can be used to de-modulate data information at a later time. Such an implementation would increase the complexity and cost of the receiver. [0009] It is therefore desirable to provide means for the control information to be decoded with a high probability of success and in a timely manner. Possible methods of increasing the probability of correctly decoding the control information are to increase the transmission power at which the control information is transmitted or to increase the duration of the transmission. [0010] However, these methods are undesirable due to the increased consumption of system resources, which in turn, decreases the amount of available resources for the transmission of data. Methods to increase transmission data rates are useless without the ability to quickly and accurately decode received information. Hence, there is a current need for improving the speed and accuracy at which decoders operate. SUMMARY [0011] Methods and apparatus are presented herein to address the above stated needs. In one aspect, an apparatus is presented for decoding an over-the-air transmission, the apparatus comprising: a memory element; and a processing element configured to execute a set of instructions stored in the memory element, the set of instructions for: setting a current set of transmission parameters equal to a previous set of transmission parameters; decoding a received message using the current set of transmission parameters; if the current set of transmission parameters fails to decode the received message, then: altering the previous set of transmission parameters by an increment to derive a new set of transmission parameters; setting the current set of transmission parameters equal to the new set of transmission parameters; and decoding the received message using the current set of transmission parameters. [0012] In another aspect, an apparatus is presented for decoding a control message that contains a set of transmission parameters associated with a data packet, the apparatus comprising: a memory element; and a processing element configured to execute a set of instructions stored in the memory element, the set of instructions for: receiving a new control message; attempting to decode the new control message using an old Walsh space that was used to decode a previous control message; and if the old Walsh space fails to decode the new control message, then attempting to decode the new control message using a new Walsh space, wherein the new Walsh space is generated by incrementing the old Walsh space. [0013] In another aspect, a method is presented for decoding an over-the-air transmission, the method comprising: receiving a new over-the-air transmission; [0014] attempting to first decode the new over-the-air transmission using an old Walsh space that was used to decode a previous over-the-air transmission; and if the old Walsh space fails to decode the new over-the-air transmission, then attempting to decode the new over-the-air transmission using a new Walsh space, wherein the new Walsh space is generated by incrementing the old Walsh space. [0015] In another aspect, a method is presented for decoding a transmission received over-the-air, the method comprising: setting a current set of transmission parameters equal to a previous set of transmission parameters; [0016] decoding a received transmission first using the current set of transmission parameters; if the current set of transmission parameters fails to decode the received transmission, then: altering the previous set of transmission parameters by an increment to derive a new set of transmission parameters; setting the current set of transmission parameters equal to the new set of transmission parameters; and decoding the received transmission using the current set of transmission parameters. BRIEF DESCRIPTION OF THE DRAWINGS [0017] FIG. 1 is a diagram of a wireless communication network. [0018] FIG. 2 is a flowchart of an embodiment for improving decoding speed. [0019] FIG. 3A is a diagram of a recursive tree structure for generating Walsh code sequences. [0020] FIG. 3B is a diagram of a bit representation of a Walsh code space. [0021] FIG. 3C is a diagram of a bit representation of another Walsh code space. Continue reading... Full patent description for Decoding using walsh space information Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Decoding using walsh space information patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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