OVSF code system and methods for CDMA stations
AssigneeInterDigital Technology Corporation
InventorsYounglok Kim, Jung-Lin Pan
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Abstract
A code indexing system for a CDMA communication station that uses orthogonal variable spreading factor (OVSF) codes has a single number mapped to each code. The new code number itself not only provides the code signature, but it is also used for the OVSF code generation. In addition, the system provides easy and fast generation of the available code list without the help of look-up table. This capability improves the dynamic code assignment.
Claims19
In a communications system where OVSF codes are selected from a set of Walsh codes represented as a binary tree having multiple layers such that a zeroth layer has one Walsh code and each successive layer has twice the number of Walsh codes as the layer it succeeds, a communication station comprising:
- a processor and associated memory device for selecting OVSF codes from the set of Walsh codes, said memory device having an index P of code values p where p represents the (p+1)−2ith Walsh code of the ith layer of Walsh codes where i is an integer such that 2i≦p<2i+1 and said processor configured to use said index to select OVSF codes.
In a communications system where OVSF codes are used and selected based upon a spreading factor SF where SF is a positive power of 2, a communication station comprising a processor and associated memory device for selecting OVSF codes, said memory device having an index P of code values p and said processor is configured to use said index to select OVSF codes from a set of codes where:
- for each integer p>3 the corresponding code is defined by C(p)=C(m+2){circle around (×)}C(k), with p=2·k+m, where k and m are integers with m=0 or 1, and
- the codes corresponding to p=1, 2, or 3 are C(1)=[1], C(2) =[1, 1], and C(3)=[1, −1]
- whereby each p represents the (p+1)−2ith code of an ith layer of codes for SF=2i where i is the unique integer such that 2i≦p<2i+1.
Dependencies are inferred from the claim text.