Method and packet radio system for controlling link adaptation

• US 7,295,850 B2
• Filed: 11/20/2003
• Issued: 11/13/2007
• Est. Priority Date: 09/25/2003
• Status: Active Grant

• Current Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Pedersen, Klaus Ingemann
• Primary Examiner(s): Gesesse; Tilahun
• Application Number:
  US10/716,530
• Publication Number:
  US 20050070319A1
• Time in Patent Office: 1,454 Days
• Field of Search: 455/450, 455/452.2, 455/67.11, 455/63.1, 455/515
• US Class Current: 455/515
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 28/22 Negotiating communication rate
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information

Abstract

A method of controlling link adaptation in a packet radio system is described, the method comprising receiving (302) a CQI (channel quality indicator) report, the CQI report including the number of parallel multi-codes, the transport block size, TBS, and the modulation scheme to be used in link adaptation; and calculating an effective code rate, ECR, based on the received CQI report. The method comprises calculating (306) new estimates for the effective code rate (ECR) and the transport block size (TBS) based on a ratio of the number of multi-codes of the CQI report and the number of multi-codes that the packet radio system has available for transmission, and executing (308) link adaptation based on the new estimates for the effective code rate (ECR) and the transport block size (TBS).

Claims

1. A method, comprising:

controlling link adaptation in a packet radio system;

receiving a channel quality indicator report, the channel quality indicator report including a number of parallel multi-codes, a transport block size, and a modulation scheme to be used in link adaptation;

calculating an effective code rate based on the received channel quality indicator report;

when a number of parallel multi-codes of the channel quality indicator report exceeds a number of multi-codes available for transmission calculating new estimates for the effective code rate and the transport block size based on a ratio of the number of multi-codes of the channel quality indicator report and the number of multi-codes available for transmission, and executing link adaptation based on new estimates for the effective code rate and the transport block size.

2. The method of claim 1, further comprising, when calculating the new estimate for the effective code rate:

calculating an increase factor by taking a logarithm of the ratio between the number of multi-codes by the channel quality indicator report and the maximum number of multi-codes available for transmission and multiplying the result by the number of ten; and

calculating the new estimate for the effective code rate based on the calculated increase factor and the effective code rate of the channel quality indicator report.

3. The method of claim 2, further comprising:

forming a table with the function of an energy to symbol to noise ratio and the effective code rate; and

obtaining the new estimate for the effective code rate based on the table with the function of the energy per symbol to noise ratio and the effective code rate, the increase factor and the modulation scheme.

4. The method of claim 1, further comprising, when calculating the new estimate for the transport block size:

quantizing the product between the new estimate for the effective code rate, a number of bits per transmission time interval for each multi-code, and the maximum number of multi-codes that the base station has available for transmission, to the nearest possible transport block size.

5. The method of claim 1, further comprising:

calculating the effective code rate proposed by the channel quality indicator report based on the ratio of the transport block size of the channel quality indicator report to a product of the number of multi-codes and the number of bits per transport time interval for each multi-block.

6. The method of claim 1, further comprising:

selecting the modulation scheme to be used in link adaptation based on the received channel quality indicator report, the modulation scheme being quadrature phase shift keying or 16-quadrature amplitude modulation scheme.

7. The method of claim 6, further comprising:

selecting the 16-quadrature amplitude modulation scheme, when the number of multi-codes that the base station has available for transmission is smaller than the number of multi-codes of the channel quality indicator report.

8. The method of claim 1, further comprising:

configuring the packet radio system to be a high speed downlink packet access radio system.

9. A packet radio system, configured to:

receive a channel quality indicator report including the number of parallel multi-codes, the transport block size, and the modulation scheme to be used in calculating a link adaptation estimate;

calculate an effective code rate;

calculate new estimates for the effective code rate and the transport block size based on a ratio of the number of multi-codes of the channel quality indicator report and the number of multi-codes that the packet radio system has available for transmission, when the number of parallel multi-codes of the channel quality indicator report exceeds the number of multi-codes that the packet radio system has available for transmission; and

execute link adaptation based on the new estimates for the effective code rate, and the transport block size.

10. The packet radio system of claim 9, wherein the packet radio system is further configured to:

calculate the new estimate for the effective code rate by

calculating an increase factor by taking a logarithm of the ratio between the number of multi-codes by the channel quality indicator report and the maximum number of multi-codes that the packet radio system has available for high speed downlink packet access transmission and multiplying the result by the number of ten, and

calculating the new estimate for the effective code rate from a function of the calculated increase factor and the effective code rate of the channel quality indicator report.

11. The packet radio system of claim 10, wherein the packet radio system is further configured to:

form a table with the function of an energy to symbol to noise ratio and the effective code rate; and

obtain the new estimate for the effective code rate based on the table with the function of the energy per symbol to noise ratio and the effective code rate, the increase factor and the modulation scheme.

12. The packet radio system of claim 9, wherein the packet radio system is further configured to:

calculate the new estimate for the transport block size by

quantizing the product between the new estimate for the effective code rate, a number of bits per transmission time interval for each multi-code, and the maximum number of multi-codes that the packet radio system has available for transmission, to the nearest possible transport block size.

13. The packet radio system of claim 9, wherein the effective code rate proposed by the channel quality indicator report is based on a ratio of the transport block size of the channel quality indicator report to a product of the number of multi-codes and the number of bits per transport time interval for each multi-block.

14. The packet radio system of claim 9, wherein the packet radio system is further configured to:

select the modulation scheme to be used in link adaptation based on the received channel quality indicator report and the modulation scheme is one of quadrature phase shift keying and 16-quadrature amplitude modulation scheme.

15. The packet radio system of claim 14, wherein the packet radio system is further configured to:

select the 16-quadrature amplitude modulation scheme, when the number of multi-codes that the base station has available for transmission is smaller than the number of multi-codes of the channel quality indicator report.

16. The packet radio system of claim 9, wherein the packet radio system is a high speed downlink packet access radio system.

17. A packet radio system, comprising:

receiving means for receiving a channel quality indicator report, the channel quality indicator report including a number of parallel multi-codes, a transport block size, and a modulation scheme to be used in link adaptation;

first calculating means for calculating an effective code rate based on the received channel quality indicator report;

second calculating means for calculating new estimates for the effective code rate when the number of parallel multi-codes of the channel quality indicator report exceeds a number of parallel multi-codes available for transmission; and

executing means for executing link adaptation when the number of parallel multi-codes of the channel quality indicator report exceeds a number of parallel multi-codes available for transmission, based on new estimates for the effective code rate and the transport block size.