Method for compensating for time dispersion in a communication system

• US 5,907,555 A
• Filed: 10/18/1995
• Issued: 05/25/1999
• Est. Priority Date: 10/18/1995
• Status: Expired due to Fees

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Raith, Alex Krister
• Primary Examiner(s): Chan, Jason
• Assistant Examiner(s): Corrielus, Jean B
• Application Number:
  US08/544,493
• Time in Patent Office: 1,315 Days
• Field of Search: 375/232, 375/261, 375/219, 375/222, 375/225, 375/227, 375/235, 375/285, 375/296, 375/341, 375/346, 375/347, 375/349, 375/350, 375/356, 375/368, 375/200, 375/377 , 375/240-242, 370/278, 370/465, 370/468, 370/335, 370/342, 370/321, 370/347, 455/54.1, 455/54.2, 455/422, 455/507, 455/67.1, 455/67.4, 371/32, 371/33, 371/5.5
• US Class Current: 370/468
• CPC Class Codes: H04B 7/005 Control of transmission; Equalising

Abstract

A method for correcting the adverse affects of time dispersion in a communication system is disclosed. A mobile station is assigned a first rate of transmission. The mobile station can then detects time dispersion in transmissions. The mobile station can then request a lower rate of transmission when the time dispersion can not be compensated by a compensator in the mobile station within a predetermined period of time. In response to the request, the system can send an indication of a second rate of transmission, which is lower than the first rate of transmission, to the mobile station. The mobile station also decreases the complexity of the compensator.

Claims

1. A method for correcting the adverse affects of time dispersion in a communication system, comprising the steps of:

assigning a mobile station a first number of timeslots or number of codes for transmission;

detecting at said mobile station time dispersion in transmissions;

sending a request, for a lower number of timeslots or number of codes for transmission, from said mobile station when said time dispersion can not be compensated by a compensator in said mobile station within a predetermined period of time;

sending an indication of a second number of timeslots or number of codes for transmission, which is lower than said first number of timeslots or number of codes for transmission, to said mobile station; and

compensating detected time dispersion based on said second number of timeslots or number of codes for transmission.

2. A method according to claim 1, wherein said compensator is a RAKE receiver.

3. A method according to claim 2, wherein a complexity of said compensator is reduced by reducing the number of taps used in said RAKE receiver.

4. A method according to claim 1, wherein said compensator is an equalizer.

5. A method according to claim 1, wherein said compensator is a Viterbi equalizer.

6. A method according to claim 5, wherein a complexity of said compensator is reduced by reducing the number of states used in said Viterbi equalizer.

7. The method of claim 1, wherein said request for a lower number of timeslots or number of codes is sent to a base station, and said indication of a second number of timeslots or number of codes is sent from the base station.