Radio receiver
AssigneeHitachi Communication Technologies, Ltd.
InventorsKiyoshi Kawamoto, Manabu Kawabe, Shiro Mazawa, Tomoyuki Ono
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Abstract
A radio receiver handles a transmitted Walsh sequence having a code length of “m” as a two-dimensional array of “a” rows and “b” columns, and performs a fast Hadamard transform process having a code length of “a” in the row direction. The absolute values of the results are added in the column direction, and a Walsh number having the maximum receiving power is selected to determine a Walsh sequence having a code length of “a.” Then, only the identified column is extracted, and a fast Hadamard transform process having a code length of “b” is applied in the column direction.
Claims15
A radio receiver in a radio mobile communication system using a code division multiple access (CDMA) communication method, comprising:
- means for calculating a first correlation between a received signal and a plurality of Walsh codes, each Walsh code having a code length of “a”, where a Walsh code having a code length of “m” is expressed as the Kronecker product of a Walsh code having a code length of “a” and a Walsh code having a code length of “b”, and “a” and “b” satisfy log2m=log2a+log2b;
- means for determining a first Walsh code having a code length “a” based on results of absolute-value additions of the first correlations for all Walsh numbers of the Walsh codes;
- means for further calculating a second correlation between the first correlations that corresponds to a Walsh number of the first Walsh code and a plurality of Walsh codes having a code length of “b”, to determine a first Walsh code having a code length of “b,” and for determining a Walsh code having a code length of “m” based on the first Walsh code having a code length of “a” and the first Walsh code having a code length of “b”.
A method for processing a received signal in a radio receiver used in a radio mobile communication system that employs a code division multiple access (CDMA) communication technique, comprising:
- producing a received sequence from the received signal;
- producing a plurality of first correlation values by correlating the received sequence with each of a plurality of Walsh codes that have a code length of “a”;
- determining a plurality of absolute-value sums from the first correlation values;
- determining a first Walsh code based on the absolute-value sums, including identifying a selected first correlation value based on the absolute-value sums, the first Walsh code corresponding to the selected first correlation value, the first Walsh code having a code length “a”;
- producing a plurality of second correlation values by correlating the selected first correlation value with each of a plurality of Walsh codes that have a code length of “b”;
- determining a second Walsh code based on the second correlation values, the second Walsh code having a code length “b”;
- and
- determining a final Walsh code that has a code length of “m” based on the first Walsh code and on the second correlation values,
- wherein the final Walsh code can be expressed as a Kronecker product of the first Walsh code and the second Walsh code, where “a”, “b”, and “m” are related by:
- log2m=log2a+log2b.
A radio receiver in a radio mobile communication system using a code division multiple access (CDMA) communication method, comprising:
- a first correlator having an input configured to receive a received sequence and having outputs for outputting a plurality of first correlation values, the first correlation values being a result of correlating the received sequence with a plurality of Walsh codes of code length “a”;
- an absolute-value adder component having inputs configured to receive the first correlation values and having outputs for outputting a plurality of absolute-value sums, the absolute-value sums being a result of a summation operation performed on the first correlation values;
- a maximum value detector having inputs configured to receive the absolute-value sums and an output for outputting a selection signal, the selection signal determined based on the absolute-value sums;
- a first selector having a first input configured to receive the first correlation values, having a second input configured to receive the selection signal, and having an output for outputting a signal representative of a selected one of the first correlation values, the selected one of the first correlation values being determined by the selection signal;
- a second correlator having an input configured to receive the signal from the selector and having outputs for outputting a plurality of second correlation values;
- and
- a second selector having inputs for receiving signals based on the second correlation values and having an output for outputting a signal representative of a second Walsh code of code length “b”,
- wherein the first Walsh code and the second Walsh code constitute a transmitted Walsh code of code length “m” expressed as a Kronecker product of the first Walsh code and of the second Walsh, where “a”, “b”, and “m” are related by:
- log2m=log2a+log2b,
- wherein the received sequence is obtained from the transmitted Walsh code.
Dependencies are inferred from the claim text.