System and method for coding in a telecommunications environment using orthogonal and near-orthogonal codes
AssigneeEricsson Inc.
InventorsKumar Balachandran, Rajaram Ramesh, Havish Koorapaty, Eric Wang, Sandeep Chennakeshu, Amer Hassan
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Abstract
A system and method for permitting variable information rates and improved error performance using orthogonal or near-orthogonal codes is disclosed. This is achieved by simultaneously transmitting two or more Walsh code words from a given orthogonal code set and/or by transmitting multiple shorter orthogonal codewords sequentially such that their combined length equals the original codeword. It should be emphasized that the present invention can be used with any orthogonal or near-orthogonal code set.
Claims57
A method of encoding an original information word having K bits that improves the coding efficiency and bandwidth utilization of a telecommunications channel using orthogonal codes, said method comprising the steps of:
- splitting the original information word into M part words, each of said M part words having K1, K2, . . . KM bits respectively;
- extending each of said M part words of the original information word by integrating each part word with an associated N-bit index word, said associated N-bit index word containing an unique identifier relating it to a specific part word, and the length of the index word being constrained by the relation N≧┌log2 M┐;
- encoding the Km+N bits of each of said extended part words using a (2Km+N, Km+N) Walsh code to obtain an extended Walsh codeword having 2Km+N symbols, where m takes successive integral values between 1 and M inclusive;
- and
- adding the M extended Walsh codewords to obtain a summed Walsh codeword having 2Kmax+N symbols, where Kmax=max [K1, K2, . . . , KM].
A method of encoding an original information word having 2K bits that improves the coding efficiency and bandwidth utilization of a telecommunications channel using orthogonal codes, said method comprising the steps of:
- splitting the original information word into a first part and a second part, each of said parts having K bits;
- concatenating said first part of the original information word with a single bit having the value zero;
- concatenating said second part of the original information word with a single bit having the value one;
- encoding the K+1 bits of said concatenated first part of the original information word using a (2K+1,K+1) Walsh code to obtain a first Walsh codeword having 2K+1 symbols;
- encoding the K+1 bits of said concatenated second part of the original information word using a (2K+1,K+1) Walsh code to obtain a second Walsh codeword having 2K+1 symbols;
- and
- adding said first Walsh codeword and said second Walsh codeword to obtain a summed Walsh codeword with 2K+1 symbols.
A method of decoding a demodulated composite Walsh codeword received over a telecommunications channel using orthogonal codes into an original information word, comprising the steps of:
- decomposing the received composite Walsh codeword into component Walsh codewords using the Fast Hadamard Transform;
- decoding each of said possibly transmitted component Walsh codewords to obtain associated possible information partwords;
- separating said decoded possible information partwords into a first list and a second list, said first list comprising decoded information partwords having a unity bit at a specified first position, and said second list comprising decoded information partwords having a zero bit at a specified second position;
- ordering said first list of decoded information partwords by decreasing value of correlation between the component Walsh codeword associated with an information partword in said first list and said received composite Walsh codeword;
- ordering said second list of decoded information partwords by decreasing value of correlation between the component Walsh codeword associated with an information partword in said second list and said received composite Walsh codeword;
- synthesizing a first data partword by selecting the highest ranking information partword from said first list and deleting the unity bit from said specified first position;
- synthesizing a second data partword by selecting the highest ranking information partword from said second list and deleting the zero bit from said specified second position;
- and
- concatenating said first and second data partwords in a specific order to obtain the original information word.
A method of encoding an original information word having M times K bits of binary information that improves the coding efficiency and bandwidth utilization of a telecommunications channel using orthogonal codes, said method comprising the steps of:
- splitting the original information word into M information partwords, each of said M information partwords having K bits;
- concatenating each of said M information partwords with N index bits, where N is not less than ┌log2 M┐ bits in length, and where the index bits for the mth information partword are the binary representation of m−1;
- encoding the K+N bits of said concatenated information partwords using a (2K+N,K+N) Walsh code to obtain a group of M Walsh codewords, each having 2K+N symbols;
- and
- summing the codewords of said set of M Walsh codewords to obtain a summed Walsh codeword with 2K+N symbols.
A method of decoding a demodulated composite Walsh codeword that is received over a telecommunications channel using orthogonal codes into an original information word, said composite Walsh codeword being 2K+N symbols in length and comprising M orthogonal Walsh codewords, said method comprising the steps of:
- decomposing the received composite Walsh codeword into M lists of component Walsh codewords having 2K+N symbols each using the Fast Hadamard Transform, each of said list comprising codewords containing a specified index;
- decoding each of said M lists of component Walsh codewords to obtain at least M information partwords each of which is K+N bits in length;
- sorting each of said decoded information partwords based upon the binary value in N specific index bits of each of the M decoded information partwords;
- ordering each of M lists of decoded information partwords by decreasing value of correlation between the component Walsh codeword associated with the decoded information partword in said list and said received composite Walsh codeword;
- synthesizing M data partwords by selecting the highest ranking decoded information partword from each of said M lists and deleting the N index bits contained in said decoded information partwords;
- and
- assembling said M data partwords in a specific order to obtain the original information word.
A method of encoding an original information word having └log2(22K−1+2K−1)┘ bits of binary information to improve the coding efficiency and bandwidth utilization of a telecommunications channel using orthogonal codes, said method comprising the steps of:
- creating an extended Walsh code set 2K symbols in length comprising all single Walsh codewords having 2K symbols and all combinations of two Walsh codewords having 2K symbols;
- mapping each distinct information word to a simple or composite codeword in said Walsh code set;
- and
- adding all codewords corresponding to said distinct information word to obtain a summed Walsh codeword 2K symbols in length.
A method of decoding a demodulated composite Walsh codeword that is received over a telecommunications channel using orthogonal codes into an original information word, said composite Walsh codeword being 2K symbols in length and comprising two or fewer orthogonal Walsh codewords, said method comprising the steps of:
- specifying a threshold value for the maximum acceptable difference in the correlation values of received Walsh codewords;
- decomposing the received composite Walsh codeword into one or more component Walsh codewords having 2K symbols each using the Fast Hadamard Transform;
- sorting the component Walsh codewords contained in said received composite Walsh codeword based upon the correlation between each component Walsh codeword and said received composite Walsh codeword;
- selecting the two highest ranking component Walsh codewords if the difference between their correlation values is less than said specified threshold value and otherwise selecting only the highest ranking component Walsh codewords;
- and
- determining the information word associated with said selected Walsh codewords using a mapping table.
A method of encoding an information word having 2K bits that improves the coding efficiency and bandwidth utilization of a telecommunications channel using orthogonal codes, said method comprising the steps of:
- splitting the information word into a first part having K+M bits and a second part having K−M bits;
- encoding the K+M bits of said first part of the information word using a (2K+M,K+M) Walsh code to obtain a first Walsh codeword having 2K+M symbols;
- encoding the K−M bits of said second part of the information word using a (2K−M,K−M) Walsh code to obtain a second Walsh codeword having 2K−M symbols;
- concatenating said first Walsh codeword and said second Walsh codeword to obtain a summed Walsh codeword with 2K+M+2K−M symbols;
- and
- modulating and transmitting said summed Walsh codeword having 2K+M+2K−M symbols over an air interface.
A method of decoding a demodulated concatenated Walsh codeword set that is received over a telecommunications channel using orthogonal codes into an original information word, said concatenated Walsh codeword set being 2K+M+2K−M symbols in length and comprising two sequentially transmitted Walsh codewords of length 2K+M symbols and 2K−M symbols, said method comprising the steps of:
- decatenating the received Walsh codeword set into a first component Walsh codeword having 2K+M symbols and a second component Walsh codeword having 2X−M symbols;
- translating each of said first component Walsh codewords into an information partword having K+M bits;
- translating each of said second component Walsh codewords into an information partword having K−M bits;
- and
- concatenating each of said two translated information partwords in the order in which they were received to recover the original information word having 2K bits.
A method of decoding a demodulated concatenated Walsh codeword set that is received over a telecommunications channel using orthogonal codes into an original information word, said concatenated Walsh codeword set being M times 2K symbols in length and comprising M sequentially transmitted Walsh codewords each 2K symbols in length, said method comprising the steps of:
- decatenating the received Walsh codeword set into M component Walsh codewords each having 2K symbols;
- translating each of said M component Walsh codewords into an information partword having K bits;
- and
- concatenating each of said M translated information partwords in a prescribed order to recover the original information word having K times M bits.
A system for encoding an original information word having K bits that improves the coding efficiency and bandwidth utilization of a telecommunications channel using orthogonal codes, said system comprising:
- means for splitting the original information word into M part words, each of said M part words having K1, K2, . . . , KM bits respectively;
- means for extending each of said M part words of the original information word by integrating each part word with an associated N-bit index word, said associated N-bit index word containing an unique identifier relating it to a specific part word, and the length of the index word being constrained by the relation N≧┌log2 M┐;
- means for encoding the Km+N bits of each of said extended part words using a (2Km+N,Km+N) Walsh code to obtain an extended Walsh codeword having 2Km+N symbols , where m takes successive integral values between 1 and M inclusive;
- and
- means for adding the M extended Walsh codewords to obtain a summed Walsh codeword having 2Kmax+N symbols, where Kmax=max[K1, K2, . . . , KM].
A system for encoding an original information word having 2K bits that improves the coding efficiency and bandwidth utilization of a telecommunications channel using orthogonal codes, said system comprising:
- means for splitting the original information word into a first part and a second part, each of said parts having k bits;
- means for concatenating said first part of the original information word with a single bit having the value zero;
- means for concatenating said second part of the original information word with a single bit having the value one;
- means for encoding the K+1 bits of said concatenated first part of the original information word using a (2K+1,K+1) Walsh code to obtain a first Walsh codeword having 2K+1 symbols;
- means for encoding the K+1 bits of said concatenated second part of the original information word using a (2K+1, K+1) Walsh code to obtain a second Walsh codeword having 2K+1 symbols;
- and
- means for adding said first Walsh codeword and said second Walsh codeword to obtain a summed Walsh codeword with 2K+1 symbols.
A system of decoding a demodulated composite Walsh codeword received over a telecommunications channel using orthogonal codes into an original information word, comprising:
- means for decomposing the received composite Walsh codeword into component Walsh codewords using the Fast Hadamard Transform;
- means for decoding each of said component Walsh codewords to obtain associated information partwords;
- means for separating said decoded information partwords into a first list and a second list, said first list comprising decoded information partwords having a unity bit at a specified first position, and said second list comprising decoded information partwords having a zero bit at a specified second position;
- means for ordering said first list of decoded information partwords by decreasing value of correlation between the component Walsh codeword associated with an information partword in said first list and said received composite Walsh codeword;
- means for ordering said second list of decoded information partwords by decreasing value of correlation between the component Walsh codeword associated with an information partword in said second list and said received composite Walsh codeword;
- means for synthesizing a first data partword by selecting the highest ranking information partword from said first list and deleting the unity bit from said specified first position;
- means for synthesizing a second data partword by selecting the highest ranking information partword from said second list and deleting the zero bit from said specified second position;
- and
- means for concatenating said first and second data partwords in a specific order to obtain the original information word.
A system for encoding an original information word having M times K bits of binary information that improves the coding efficiency and bandwidth utilization of a telecommunications channel using orthogonal codes, said system comprising:
- means for splitting the original information word into M information partwords, each of said M information partwords having K bits;
- means for concatenating each of said M information partwords with N index bits, where N is not less than ┌log2 M┐ bits in length, and where the index bits for the mth information partword are the binary representation of m−1;
- means for encoding the K+N bits of said concatenated information partwords using a (2K+N,K+N) Walsh code to obtain a group of M Walsh codewords, each having 2K+N symbols;
- and
- means for summing the codewords of said set of M Walsh codewords to obtain a summed Walsh codeword with 2K+N symbols.
A system for decoding a demodulated composite Walsh codeword that is received over a telecommunications channel using orthogonal codes into an original information word, said composite Walsh codeword being 2K+N symbols in length and comprising M orthogonal Walsh codewords, said system comprising:
- means for decomposing the received composite Walsh codeword into at least M component Walsh codewords having 2K+N symbols each using the Fast Hadamard Transform;
- means for decoding each of said at least M component Walsh codewords to obtain at least M information partwords each of which is K+N bits in length;
- means for sorting said at least M decoded information partwords into M lists based upon the binary value in N specific bits of each of the M decoded information partwords;
- means for ordering each of M lists of decoded information partwords by decreasing value of correlation between the component Walsh codeword associated with the decoded information partword in said list and said received composite Walsh codeword;
- means for synthesizing M data partwords by selecting the highest ranking decoded information partword from each of said M lists and deleting the N index bits contained in said decoded information partwords;
- and
- means for concatenating said M data partwords in a specific order to obtain the original information word.
A system for encoding an original information word having 2K+1 bits of binary information to improve the coding efficiency and bandwidth utilization of a telecommunications channel using orthogonal codes, said system comprising:
- means for creating a Walsh code set 2K symbols in length comprising all single Walsh codewords having 2K symbols and all combinations of two Walsh codewords having 2K symbols;
- means for mapping each distinct information word to a simple or composite codeword in said Walsh code set;
- and
- means for adding all codewords corresponding to said distinct information word to obtain a summed Walsh codeword 2K symbols in length.
A system for decoding a demodulated composite Walsh codeword that is received over a telecommunications channel using orthogonal codes into an original information word, said composite Walsh codeword being 2K symbols in length and comprising two or fewer orthogonal Walsh codewords, said system comprising:
- means for specifying a threshold value for the maximum acceptable difference in the correlation values of received Walsh codewords;
- means for decomposing the received composite Walsh codeword into one or more component Walsh codewords having 2K symbols each using the Fast Hadamard Transform;
- means for sorting the component Walsh codewords contained in said received composite Walsh codeword based upon the correlation between each component Walsh codeword and said received composite Walsh codeword;
- means for selecting the two highest ranking component Walsh codewords if the difference between their correlation values is less than said specified threshold value and otherwise selecting only the highest ranking component Walsh codewords;
- and
- means for determining the information word associated with said selected Walsh codewords using a mapping table.
A system for encoding an information word having 2K bits that improves the coding efficiency and bandwidth utilization of a telecommunications channel using orthogonal codes, said system comprising:
- means for splitting the information word into a first part having K+M bits and a second part having K−M bits;
- means for encoding the K+M bits of said first part of the information word using a (2K+M,K+M) Walsh code to obtain a first Walsh codeword having 2K+M symbols;
- means for encoding the K−M bits of said second part of the information word using a (2K−M,K−M) Walsh code to obtain a second Walsh codeword having 2K−M symbols;
- means for concatenating said first Walsh codeword and said second Walsh codeword to obtain a summed Walsh codeword with 2K+M+2K−M symbols;
- and
- means for modulating and transmitting said summed Walsh codeword having 2K+M+2K−M symbols over an air interface.
A system of decoding a demodulated concatenated Walsh codeword set that is received over a telecommunications channel using orthogonal codes into an original information word, said concatenated Walsh codeword set being 2K+M+2K−M symbols in length and comprising two sequentially transmitted Walsh codewords of length 2K+M symbols and 2K−M symbols, said system comprising:
- means for decatenating the received Walsh codeword set into a first component Walsh codeword having 2K+M symbols and a second component Walsh codeword having 2K−M symbols;
- means for translating each of said first component Walsh codewords into an information partword having K+M bits using a mapping table;
- means for translating each of said second component Walsh codewords into an information partword having K−M bits using a mapping table;
- and
- means for concatenating each of said two translated information partwords in the order in which they were received to recover the original information word having 2K bits.
A system for decoding a demodulated concatenated Walsh codeword set that is received over a telecommunications channel using orthogonal codes into an original information word, said concatenated Walsh codeword set being M times 2K symbols in length and comprising M sequentially transmitted Walsh codewords each 2K symbols in length, said system comprising:
- means for decatenating the received Walsh codeword set into M component Walsh codewords each having 2K symbols;
- means for translating each of said M component Walsh codewords into an information partword having K bits using a mapping table;
- and
- means for concatenating each of said M translated information partwords in the order in which they were received to recover the original information word having K times M bits.
Dependencies are inferred from the claim text.