Code-resource distribution method in CDMA communication system

Abstract

The method includes following steps: registering state of each node on code tree in code division multiple access (CDMA) system as idle or non-idle, inputting spread spectrum factor to be allotted; using four nodes with spread spectrum factor as 4 to be as root node to divide code tree to four groups, and to record remanent code resources in each layer under group; based on spread spectrum factor to be allotted and number of remanent code resources to decide specific branches to allot resources, and find out nodes under the branches to carry out allotting; modifying state of allotted node, and condition of remanent resources. Using complete binary tree of resources of CDMA system, the invention divides code resources to groups of allotting resource so as to reduce range to search resource effectively, and time complexity of implementation. Especially, when all nodes of code tree are idle, the method realizes allotment simply and quickly.

Description

technical field [0001] The present invention relates to a method for allocating code resources in the field of code division multiple access communication systems, in particular to a method for allocating orthogonal variable spread spectrum codes in WCDMA (Wideband Code Division Multiple Access) wideband code division multiple access communication systems . Background technique [0002] The existing CDMA communication system uses OVSF technology to ensure the orthogonality between different spreading codes of different lengths. The code tree structure of the OVSF code is shown in Figure 1. The length of the OVSF code word is equal to its spreading factor, which is an integer power of 2, that is, SF=2 K (K takes a positive integer). For an OVSF code group with a certain codeword length, the total number of codewords it includes is equal to its codeword length, that is, there are SF OVSF codes with a length of SF on the same layer of the code tree. In the code tree, the cod...

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Problems solved by technology

Although this can improve the utilization rate of code resources, it also increases the complexity of code resource allocation, especially when the allocated SF is larger, the number of layers that need to be traversed to search the code tree will be more, and the nodes to be searched will be smaller. more

The most extreme case is that when the entire code table is free, if a spreading code with SF=512 needs to be allocated, according to the above principles, it may be necessary to traverse all the nodes on the entire code tree to finally select a suitable code Words are allocated, which greatly increases the time complexity of the implementation

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