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The invention includes a system and methods for orthogonal variable spreading factor (OVSF) code assignment, de-allocation and code tree pruning. The invention also includes OVSF code identification and storage schemes. Embodiments are provided for code tree pruning, code assignment and de-allocatio

The invention includes a system and methods for orthogonal variable spreading factor (OVSF) code assignment, de-allocation and code tree pruning. The invention also includes OVSF code identification and storage schemes. Embodiments are provided for code tree pruning, code assignment and de-allocation. These embodiments apply to both slotted and non-slotted code division multiple access systems.

대표청구항 ▼

What is claimed is: 1. A method for reassigning codes of an orthogonal variable spreading factor code tree in code division multiple access communications to a new call, the code tree having a plurality of codes at differing spreading factors and having a plurality of branches between the codes of

What is claimed is: 1. A method for reassigning codes of an orthogonal variable spreading factor code tree in code division multiple access communications to a new call, the code tree having a plurality of codes at differing spreading factors and having a plurality of branches between the codes of different spreading factors, if a particular code of the code tree is assigned, a lower spreading factor code of the code tree connected to that code by one of the branches is blocked from assignment, if a code of the code tree is blocked, a code of the tree of a lower spreading factor connected to that code by one of the branches is blocked from assignment, the method comprising: finding a code of a highest spreading factor in a time slot; determining if a leftward code of the highest spreading factor code in the time slot is available; relocating the new call into the leftmost available code in the time slot; and repeating, for a next lower spreading factor, finding a code of the next lower spreading factor in the time slot, determining if a leftward code is available in the time slot, and relocating the new call to the leftward available code. 2. The method of claim 1 in wireless communications using multiple time slots, and further comprising: for another time slot: finding a code of a highest spreading factor in the other time slot; determining if a leftward code of the highest spreading factor code in the other time slot is available; relocating the new call into the leftmost available code in the other time slot; and repeating, for a next lower spreading factor, finding a code of the next lower spreading factor in the other time slot, determining if a leftward code is available in the other time slot, and relocating the new call to the leftward available code in the other time slot. 3. The method of claim 2 wherein the other time slot is a time slot adjacent to the first time slot in a rightward direction. 4. The method of claim 1 further comprising: stopping the method if the number of relocations reaches a predetermined number. 5. The method of claim 1 wherein the method is invoked when a predefined number of new call arrivals is received. 6. A method for reassigning codes of an orthogonal variable spreading factor code tree used in code division multiple access communications to a new call, comprising: selecting a first code in the code tree of a highest spreading factor in a timeslot to be evaluated and assigning the first code to the new call; searching a subsequent time slot if there are no available codes of that spreading factor in the first timeslot; determining if the new call can be relocated to a different code in the spreading factor; relocating the new call to the different code in the spreading factor, if possible; selecting the next code in the spreading factor and repeating the determining; and selecting a first code in the next lower spreading factor if there are no more codes in a current spreading factor, and repeating the determining. 7. The method according to claim 6, wherein the first code is a leftmost code in the tree. 8. The method according to claim 7, wherein the relocating includes relocating the new call to a code to the left in the tree. 9. The method according to claim 7, wherein the relocating includes relocating the new call to a code to the right in the tree. 10. The method according to claim 6, wherein the first code is a rightmost code in the tree. 11. The method according to claim 10, wherein the relocating includes relocating the new call to a code to the left in the tree. 12. The method according to claim 10, wherein the relocating includes relocating the new call to a code to the right in the tree. 13. The method according to claim 6, wherein the searching is not performed, whereby the method only reassigns the new call to a code within a single timeslot. 14. The method according to claim 6, wherein the method is performed for each new call. 15. The method according to claim 6, wherein the method is performed periodically. 16. The method according to claim 6, wherein the method limits the number of code reassignments to the new call. 17. The method according to claim 6, further comprising: evaluating a fragmentation parameter of the code tree; and performing the method if the fragmentation parameter exceeds a threshold.