Path search method for CDMA communication systems
OwnerYan Zhang, Jingdong Lininventors
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Abstract
The embodiments of this invention relate generally to wireless telecommunication systems and, more particularly, to spread spectrum code division multiple access communication systems that employ a pilot-channel for path search and acquisition and for allocating fingers of a multifinger correlator, such as one found in a RAKE receiver. While the path search is an important part of the RAKE process, conventional path search methods require a large storage space for implementing the required correlation algorithms. One of the advantages of this invention is the noticeable reduction of the required storage space.
Claims15
A correlation system for the path search in a code division multiple access communication system, such as WCDMA or TD-SCDMA, employing a pilot-channel for path searching and acquisition and for allocating fingers of a multi-finger RAKE, the path search correlation system comprising:
- a multiplier;
- an adder;
- and
- a data storage for holding a local sequence and received data, where the local sequence is stored in a (W−1+N)-bit long storage area and the received data is stored in a [NK(Tc/t)]-bit long storage area, and wherein:
- W is the number of correlation results;
- N is the correlation algorithm (integral) length;
- K is the length of a data point in bits;
- Tc is one chip interval;
- and
- t is the sampling interval.
A path search correlator in a RAKE section of a CDMA (Code Division Multiple Access) communication system, comprising:
- a multiplier;
- an adder;
- a (W−1+N)-bit long first data storage for storing a local sequence, wherein W is the number of correlation results and N is the bit-length of a local sequence which is used to correlate with an incoming sampled signal, and wherein the local sequence is repeated as many times as necessary to fill the first data storage;
- a [NK(Tc/t)-bit long second data storage for storing the data bits of a portion of the sampled signal, wherein K is the length of a sampled data unit in bits, Tc is one chip interval, and t is the sampling interval;
- and
- a configuration in which the data in the second data storage is incrementally moved against the data in the first data storage, wherein each increment is equal to the sampling interval, and wherein at every increment each data bit of the second data storage is multiplied by the corresponding bit of the first data storage, and wherein the result of all multiplications, at each location, are added together.
A path search system in a spread spectrum code division multiple access communication system, the path search system comprising:
- a multiplier;
- an adder;
- a first data storage for storing a local sequence that is used to correlate with an incoming sampled signal, wherein the first storage area is longer than the local sequence, and wherein the local sequence is repeated as many times as necessary to fill the first data storage;
- and
- a [NK(Tc/t)-bit long second data storage for storing the data bits of a portion of the sampled signal, wherein N is the bit-length of the local sequence, K is the bit-length of a sampled data unit, Tc is one chip interval, and t is the sampling interval.
A path search structure in a CDMA system, the path search structure comprising:
- a multiplier;
- an adder;
- a first data storage area for storing a local sequence, wherein the first storage area is longer than the local sequence, and wherein the local sequence is repeated as many times as necessary to fill the first data storage;
- a second data storage area for storing the data bits of a portion of the sampled signal, wherein the second data storage area is shorter than the first data storage area;
- and
- an arrangement wherein the data residing in the first data storage area is correlated with the data residing in the second data storage area while sliding the data within the second data storage area against the data within the first data storage area and storing the results of the correlations.
A RAKE receiver structure in a CDMA system, the RAKE receiver comprising:
- a Radio Frequency receiver;
- an Analog-to-Digital converter;
- a RAKE finger;
- a RAKE combiner;
- and
- a path search system, further comprising:
- a multiplier;
- an adder;
- a first data storage area for storing a local sequence, wherein the first storage area is larger than the local sequence, and wherein the local sequence is repeated as many times as necessary to fill the first data storage;
- a second data storage area for storing the data bits of a portion of the sampled signal, wherein the second data storage area is shorter than the first data storage area;
- and
- a configuration wherein the data residing in the first data storage area is correlated with the data residing in the second data storage area while sliding the data within the second data storage area against the data within the first data storage area.
A RAKE receiver in a spread spectrum code division multiple access communication system employing a pilot-channel for path searching, the RAKE receiver comprising:
- a Radio-Frequency receiver;
- an Analog-to-Digital converter;
- a RAKE finger;
- a RAKE combiner;
- and
- a path search structure, further comprising:
- a multiplier;
- an adder;
- a (W−1+N)-bit long first data storage for storing a local sequence, wherein W is the number of correlation results and N is the bit-length of a local sequence which is used to correlate with an incoming sampled signal, and wherein the local sequence is repeated as many times as necessary to fill the first data storage;
- and
- a [NK(Tc/t)-bit long second data storage for storing the data bits of a portion of the sampled signal, wherein K is the length of a sampled data unit in bits, Tc is one chip interval, and t is the sampling interval.
A RAKE receiver structure in a CDMA system, the RAKE receiver structure comprising:
- a means for receiving a Radio-Frequency signal;
- a means for converting an analog signal to a digital signal;
- a RAKE finger;
- a RAKE combiner;
- and
- a path search system, further comprising:
- a means for multiplication;
- a means for addition;
- a means for holding a local sequence;
- and
- a means for holding the received data;
- and
- a means for correlating the local sequence with the received data.
A method of path searching in a CDMA system by correlating received data with a local sequence, the method comprising:
- a step of receiving sampled and quantized data;
- a step of holding at least a part of the received data in a buffer, wherein the buffer is [NK(Tc/t)] bits long, and wherein K is the length of a data unit in bits, Tc is one chip interval, t is the sampling interval, and N is the length of the local sequence;
- a step of holding the local sequence in a storage area, wherein the storage area is larger than the local sequence and the buffer, and wherein the local sequence is repeated until the storage area is filled;
- a step of sliding the buffer data, incrementally, against the local sequence data of the storage area, wherein each increment is equal to the sample interval of the received data;
- a step of multiplying, at each increment, each bit of the buffer data by the corresponding bit of the storage area;
- a step of adding the results of all multiplications at each increment;
- and
- a step of storing the results of the addition at each increment.
A path search method in a CDMA system, the method comprising:
- holding a repetition of a local sequence in a storage area larger than the local sequence;
- receiving a stream of sampled data;
- holding a part of the received data in a buffer shorter than the storage area, wherein the storage area is [NK(Tc/t)] bits long, and wherein K is the length of a received data unit in bits, Tc is one chip interval, t is the sampling interval, and N is the length of the local sequence;
- moving the data of the storage area, incrementally, against the data in the buffer;
- multiplying the buffer data, bit-by-bit at each increment, by the corresponding data in the storage area;
- and
- adding the results of all multiplications at each increment.
A correlation system for the path search of incoming signals in a code division multiple access communication system, the correlation system comprising:
- a multiplier;
- an adder;
- a first data storage area for holding a local sequence that is used for correlation with an incoming data sequence which itself is the result of sampling the incoming signals, wherein the first data storage area is larger than the length of the local sequence, and wherein the local sequence is repeated to fill the available storage area:
- a second data storage area which is smaller than the first data storage area, for holding a portion of the incoming data sequence;
- and
- a configuration in which the data in the second data storage area is incrementally moved against the data in the first data storage area, wherein each increment is equal to the sampling interval of the incoming signals, and wherein at every increment each data bit of the second data storage area are multiplied by the corresponding bit of the first data storage area, and wherein the result of all multiplications, at each location, are added together.
Dependencies are inferred from the claim text.