Code tree fragmentation in call admission control

• US 20050070295A1
• Filed: 12/31/2003
• Published: 03/31/2005
• Est. Priority Date: 09/30/2003
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Horanieh, Moussa
• Granted Patent: US 7,065,365 B2
• Time in Patent Office: Days
• US Class Current: 455/453
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• CPC Class Codes: H04B 2201/709709 Methods of preventing interference
• CPC Class Codes: H04J 13/0044 OVSF [orthogonal variable spreading factor]
• CPC Class Codes: H04J 13/20 having an orthogonal variable spreading factor [OVSF]
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 72/563 of the wireless resources
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02

Abstract

The invention provides various embodiments for radio resource management. In one embodiment, resources are assigned to users in a slotted wireless communication system having candidate timeslots. An interference level is determined for each candidate timeslot. An amount of resources available for assignment in each candidate timeslot is determined. A measurement of fragmentation of codes in an orthogonal variable spreading factor (OVSF) tree in each candidate timeslot is determined. A Figure of Merit for each time slot is determined using the determined interference level, the amount of available resources and the code fragmentation in the OVSF tree for each candidate timeslot. The resources are assigned from the candidate timeslot having a best Figure of Merit.

Claims

1. A method for assigning resources to users in a slotted wireless communication system having candidate timeslots, the method comprising:

an interference level is determined for each candidate timeslot;

an amount of resources available for assignment in each candidate timeslot is determined;

a measurement of fragmentation of codes in a orthogonal variable spreading factor (OVSF) tree in each candidate timeslot is determined;

a Figure of Merit for each time slot is determined using the determined interference level, the amount of available resources and the code fragmentation in the OVSF tree for each candidate timeslot; and

the resources are assigned from the candidate timeslot having a best Figure of Merit.

2. The method of claim 1 wherein the resources are resource units in a time division duplex/code division multiple access communication system.

3. The method of claim 1 wherein the determining the Figure of Merit for an ith timeslot is per

F_i=−

α

Δ

I_i+β

f(C_i)+FDi

where F_i is the Figure of Merit for the ith timeslot, a and B are weighting parameters, Δ

I_i is a difference between an interference signal code power (ISCP) measurement of the i^th timeslot and a minimum ISCP measurement of all the candidate timeslots, f(C_i) is an amount of resource units that can be used by a coded composite transport channel (CCTrCH) of interest in the ith timeslot and FDi is a measure of OVSF code tree fragmentation in the ith timeslot.

4. A radio network controller comprising:

a radio resource management device for assigning resources to users in a slotted wireless communication system having candidate timeslots, the radio resource management device determines an interference level for each candidate timeslot, determines an amount of resources available for assignment in each candidate timeslot, determines a measurement of fragmentation of codes in a orthogonal variable spreading factor (OVSF) tree in each candidate timeslot, determines a Figure of Merit for each time slot using the determined interference level, the amount of available resources and the code fragmentation in the OVSF tree for each candidate timeslot, and assigning the resources assigned from the candidate timeslot having a best Figure of Merit.

5. The radio network controller of claim 4 wherein the resources are resource units in a time division duplex/code division multiple access communication system.

6. The radio network controller of claim 4 wherein the determining the Figure of Merit for an ith timeslot is per

F_i=−

α

·

Δ

I_iβ

·

f(C_i)+FDi

where F_i is the Figure of Merit for the ith timeslot, α and

β

are weighting parameters, Δ

I_i is a difference between an interference signal code power (ISCP) measurement of the i^th timeslot and a minimum ISCP measurement of all the candidate timeslots, f(C_i) is an amount of resource units that can be used by a coded composite transport channel (CCTrCH) of interest in the ith timeslot and FDi is a measure of OVSF code tree fragmentation in the ith timeslot.

7. A radio network controller for assigning resources to users in a slotted wireless communication system having candidate timeslots, the radio network controller comprising:

means for determining an interference level for each candidate timeslot;

means for determining an amount of resources available for assignment in each candidate timeslot;

means for determining a measurement of fragmentation of codes in a orthogonal variable spreading factor (OVSF) tree in each candidate timeslot;

means for determining a Figure of Merit for each time slot using the determined interference level, the amount of available resources and the code fragmentation in the OVSF tree for each candidate timeslot; and

means for assigning the resources from the candidate timeslot having a best Figure of Merit.

8. The radio network controller of claim 7 wherein the resources are resource units in a time division duplex/code division multiple access communication system.

9. The radio network controller of claim 7 wherein the determining the Figure of Merit for an ith timeslot is per

F_i=−

α

Δ

I_i+β

f(C_i)+FDi

where F_i is the Figure of Merit for the i^th timeslot, α and

β

are weighting parameters, Δ

I_i is a difference between an interference signal code power (ISCP) measurement of the i^th timeslot and a minimum ISCP measurement of all the candidate timeslots, f(C_i) is an amount of resource units that can be used by a coded composite transport channel (CCTrCH) of interest in the ith timeslot and FDi is a measure of OVSF code tree fragmentation in the ith timeslot.

10. A method for determining an amount of orthogonal variable spreading factor (OVSF) code fragmentation, the method comprising:

determining a number of used codes and an actual number of blocked codes;

using a look-up table, determining a optimum number of blocked codes based on the number of used codes; and

subtracting the optimum number of blocked codes from the actual number of blocked codes as an indicator of the amount of OVSF code fragmentation.

11. A method for radio bearer release in a slotted communication system using orthogonal variable spreading factor (OVSF) code trees, the method comprising:

a radio bearer is released and resource units of the radio bearer are released in timeslots used by the radio bearer; and

pruning a OVSF code tree of each timeslot having released resource units only within that timeslot.

12. A method for reducing code tree pruning a slotted communication system using orthogonal variable spreading factor (OVSF) code trees, the method comprising:

determining when a user is blocked during call admission control; and

only performing code tree pruning when the user is blocked during call admission control.