new non-blocking eovsf codes for multi-rate wcdma system
Orthogonal variable spreading factor (OVSF) codes are employed in the third generation (3G) wideband code division multiple access (WCDMA) wireless system as channelization codes. Any two codes OVSF of different levels are orthogonal if and only if one of two codes is not ancestor/descendant in each other. Therefore, when an OVSF code is assigned to a user, it blocks all of its ancestor and descendant codes. This results in a major drawback of OVSF codes, called blocking property: When an OVSF code is assigned, it blocks all of its ancestor and descendant codes from assignment because they are not orthogonal to each other. This paper presents a new extended orthogonal variable spreading factor (EOVSF) codes to support a quite large number code candidates for more user used in multi-rate next-generation wireless system. Thereby, no EOVSF code blocks the assignment of any other EOVSF code. It decreases more reject probability in WCDMA system.
eovsf codes ovsf codes wcdma third generation (3g)