Method and apparatus for improving asynchronous transfer mode operation over noisy, high speed wireless links

Abstract

In an asynchronous transfer mode (ATM) system, an apparatus is used to improve the transmission and reception of encoded ATM information over a wireless link having an encoder for encoding the information, assembling the information into a frame format and interleaving of the information for transmission over the wireless link. In addition, the apparatus also has a decoder for decoding information received via the wireless link which was encoded by a similar apparatus transmitting the information over the wireless link. Further, methods utilized by the encoder and decoder to improve transmission include increasing the bandwidth efficiency by dropping a header byte from every ATM cell; assembling separate header and payload frames; utilizing and rearranging idle/unassigned cells in the payload frame for storing and, thereby, increasing error correction code in the frame; dynamically changing the coding of frame in real time from one payload frame to optimize utilization of the mumber of available idle/unassigned cells occurring in each frame; restoring the positions of all idle/unassigned cells to their original position at a receiving end in order to leave the Cell Delay Variation unaffected; interleaving the frames to reduce burst errors during transmission; preservation of overhead parity bits present in the original frames received from a wireline link; cell Header error detection and correction through the use of a generated syndrome; and a synchronization pattern detection method during decoding.

1 - 14 . (canceled)  
     
     
         15 . A method of transmitting ATM cells over a wireless link comprising the steps of: 
 receiving a plurality of ATM cells each having a header and a payload, said header including at least one Header Error Correction byte;    dropping said at least one Header Error Correction (HEC) byte from said header of each ATM cell to thereby leave an unoccupied byte space in said header;    inserting other non-HEC information into said unoccupied byte space; and    transmitting each of said plurality of ATM cells.    
     
     
         16 . A method according to  claim 15  further comprising the step of: 
 regenerating said Header Error Correction byte from the remaining bytes in said header of each ATM cell after transmission of each cell.    
     
     
         17 . A method according to  claim 15  further comprising: 
 generating a header syndrome; and    identifying bits in error using said header syndrome;    wherein when a single bit in error is identified in the header, correction of said bit in error is performed, and when multiple bits in error are identified in the header, an ATM containing said multiple bits in error is dropped and replaced by an idle/unassigned cell.    
     
     
         18 . (canceled)  
     
     
         19 . A method for encoding ATM cells for transmission over a wireless link comprising the steps of: 
 receiving an ATM cell stream comprised cells each including a header and payload;    assembling a header frame comprised of headers of said plurality of ATM cells.    
     
     
         20 . A method according to  claim 19 , wherein said step of assembling said header frame further comprises: 
 partitioning said header frame comprised of headers of said predetermined number of ATM cells into a first section and a second section;    said first section comprised of a second predetermined number of headers from said first predetermined number of ATM cells and an added cell made up of control bytes; and    said second section comprised of having a third predetermined number of headers from said first predetermined number of ATM cells.    
     
     
         21 . A method for encoding ATM cells for transmission over a wireless link comprising the steps of: 
 receiving an ATM cell stream comprised of a plurality of ATM cells;    assembling a payload frame comprised of payloads of said plurality of ATM cells.    
     
     
         22 . A method according to  claim 21  wherein said payload frame is comprised of a predetermined number of said plurality of ATM cells arranged in a matrix comprised of an i number of rows and a j number of columns.  
     
     
         23 . A method according to  claim 22 , wherein said step of assembling said payload frame further comprises: 
 adding a predetermined number of bytes of Payload Error Correction Code (PECC) to all i number of rows of said payload frame.    
     
     
         24 . A method according to  claim 23 , wherein said Payload Error Correction Code is generated by a Reed-Solomon coding scheme.  
     
     
         25 . A method for encoding ATM cells for transmission over a wireless link comprising the steps of: 
 receiving an ATM cell stream comprised of a plurality of ATM cells from a wireline interface;    detecting idle/unassigned cells within said cell stream;    assembling a payload frame comprised of payloads from said plurality of ATM cells; and    placing at least some of the detected idle/unassigned cells in a selected portion of the payload frame.    
     
     
         26 . A method according to  claim 25 , wherein said step of placing idle/unassigned cells further comprises: 
 adding extra Payload Error correction code in those idle/unassigned cells which are placed in the selected portion of said payload frame.    
     
     
         27 . A method according to  claim 25 , further comprising: 
 generating a header syndrome; and    identifying bits in error using said header syndrome;    wherein when a single bit in error is identified in the header, correction of said bit in error is performed, and when multiple bits in error are identified in the header, an ATM cell containing said multiple bits in error is dropped and replaced by an idle/unassigned cell.    
     
     
         28 . A method for encoding ATM cells in a frame for transmission over a wireless link comprising the steps of: 
 detecting idle/unassigned cells in an ATM cell stream;    inserting error correction code into some of said idle/unassigned cells;    setting a first information field within said frame at a first state when error correction code has been inserted into any idle/unassigned cells within said frame; and    setting said first information field at a second state when no error correction code has been inserted into idle/unassigned cells within said frame.    
     
     
         29 . A method according to  claim 28 , further comprising the step of: 
 storing a number of idle/unassigned cells used for extra error correction code in a second information field within said frame when said first information field has been set at said first state.    
     
     
         30 . A method of restoring an ATM cell stream sequence after transmission over a wireless link comprising the steps of: 
 recording the original positions of idle/unassigned cells in a cell stream sequence before being moved during assembly of an ATM frame prior to transmission of said frame over said wireless link; and    restoring said original positions of said idle/unassigned cells within said cell stream based upon said recorded original positions after transmission of said frame over said wireless link.    
     
     
         31 . An apparatus for receiving an ATM cell stream sequence via a wireline link, encoding said ATM cell stream for transmission of data via a wireless link, receiving and decoding encoded wireless data received via said wireless link and transmitting another ATM cell stream sequence via said wireline link, comprising: 
 a wireline link interface for receiving said cell stream sequence from said wireline link and transmitting said another cell stream sequence;    an encoder receiving cell stream data from said wireline interface, encoding said cell stream data and outputting encoded cell data;    a wireless interface for receiving said encoded cell data from said encoder, transmitting said encoded cell data via said wireless link and receiving previously encoded cell data;    a decoder receiving said previously encoded cell data from said wireless interface, decoding said previously encoded cell data and outputting said another cell stream sequence to said wireline interface; and    a control unit for controlling said interfaces, encoder and decoder.    
     
     
         32 . An apparatus according to  claim 31 , wherein said encoder further comprises: 
 a cell preprocessor for receiving said cell stream data, monitoring header bytes of incoming cells, detecting    idle/unassigned cells and outputting cell data;    a frame assembler for receiving said cell data from said cell preprocessor assembling said data in a frame and outputting said frame;    an encoder unit for receiving said frame and encoding said frame according to a predetermined coding scheme;    and an interleaver for interleaving and transmitting said frame to said wireless interface.    
     
     
         33 . An apparatus according to  claim 31 , wherein said decoder further comprises: 
 an acquisition and synchronization unit for receiving previously encoded cell data from said wireless interface,    searching for a predetermined synchronization pattern in said previously encoded cell data, declaring a synchronization pattern, and outputting interleaved cell data;    a byte deinterleaver for deinterleaving said interleaved cell data received from said acquisition and synchronization unit, deinterleaving said interleaved cell data and outputting deinterleaved cell data;    a decoder for decoding said deinterleaved cell data received from said byte deinterleaver according to a predetermined coding scheme and outputting decoded cell data;    and a cell assembler for receiving said decoded cell data; assembling the decoded cell data into said another cell stream sequence, and outputting said another cell stream data to said wireline interface for transmission via said wireline link.    
     
     
         34 . A method nor decoding interleaved and encoded data received over a wireless link comprising: 
 detecting a predetermined synchronization pattern in said encoded data received over said wireless link;    passing said data to a deinterleaver and decoder when said predetermined synchronization pattern has been detected;    determining a number of bytes in error in said data; and    declaring a synchronization mode when the number of bytes in error between successive synchronization patterns is less than a predetermined number.    
     
     
         35 . A method according to  claim 34 , wherein said step of detecting includes setting a pattern search window of a predetermined number of bytes.  
     
     
         36 . A method according to  claim 34  further comprising a step of declaring an identification of said synchronization pattern when a predetermined number of bytes of data are detected as matching said predetermined synchronization pattern.  
     
     
         37 . A method according to  claim 36 , wherein said predetermined number of bytes is two.  
     
     
         38 . A method for decoding interleaved and encoded data transmitted and received over a wireless link comprising: 
 deinterleaving said data and rearranging said data into a predetermined frame;    decoding said data according to a predetermined coding scheme;    detecting if any cells within a Header frame within said predetermined frame are uncorrectable; and    replacing detected uncorrectable cells with idle/unassigned cells.    
     
     
         39 . (canceled)