Synchronous demodulation apparatus of base transceiver station in interim standard-2000 system

• US 7,167,716 B2
• Filed: 12/27/2002
• Issued: 01/23/2007
• Est. Priority Date: 02/08/2002
• Status: Active Grant

• Current Assignee: Pantech Corporation (Ideahub, Inc.)
• Original Assignee: Curitel Communications Incorporated
• Inventors: Kim, Jin-Il
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): NGUYEN, TUAN HOANG
• Application Number:
  US10/330,737
• Publication Number:
  US 20030152172A1
• Time in Patent Office: 1,488 Days
• Field of Search: 455/295, 455/296, 455/303, 455/304, 455/502, 455/561, 370/203, 370/319, 370/335, 370/342, 375/144, 375/148, 375/240.01, 375/240.29, 375/316, 375/346
• US Class Current: 455/502
• CPC Class Codes: H04B 1/71075 Parallel interference cancellation
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0224 using sounding signals

Abstract

The present invention provides a synchronous demodulation apparatus of a base transceiver station in an Interim Standard-2000 (IS-2000) system, including a first synchronous demodulation unit, a received signal delay unit, an interference signal regeneration unit and a second synchronous demodulation unit. In comparison with an asynchronous demodulation apparatus used in an Interim Standard-95 (IS-95), it is possible for the inventive apparatus to improve a reception function approximately 3dB and ultimately increase the number of subscribers.

Claims

1. A synchronous demodulation apparatus of a base transceiver station in a communication system, comprising:

a first synchronous demodulation unit for receiving received signals each of which includes a pilot channel signal and a traffic channel signal, demodulating the received signals to generate demodulated signals, and outputting the demodulated user signals;

a channel estimation unit for estimating channel parameters for each of the mobile stations based on the pilot channel signals transmitted from the mobile stations, and generating estimated channel parameters;

a received signal delay unit for delaying the received signal and outputting a delayed signal which is delayed in one symbol from the received signal;

an interference signal regeneration unit for generating interference signals based on the demodulated user signals and the estimated channel parameters, removing interference signals from the delayed signals, and outputting interference-cancelled-signals in which the interference signals are removed; and

a second synchronous demodulation unit for demodulating the interference-cancelled-signals and outputting demodulated signals,

wherein each of the channel parameters includes an amplitude distortion and a phase distortion.

2. The synchronous demodulation apparatus as recited in claim 1, wherein the interference signal regeneration unit includes:

multipliers, each of which multiplies the demodulated user signal (d'"'"'_{1,. . .,} d'"'"'_k) by the channel parameter (A₁(t−

T_b),. . . , A_k(t−

T_b) so as to generate and output a phase distorted signal;

despreaders, each of which despreads the phase distorted signal and generates a despread signal (s'"'"'₁(t−

T_b),. . ., s'"'"'_k(t−

T_b)) based on the phase distorted signal;

adders, each for adding the despread signals (s'"'"'₁(t−

T_b),. . ., s'"'"'(_k(t−

T_b)) except for the despread signal corresponding to its order so as to generate and output an interference signal; and

subtractors, each each of which removes the interference signal from the delayed signal (r(r−

T_b)) and outputs the interference-cancelled-signal to the second demodulation unit.

3. A synchronous demodulation method applied to a base transceiver station in a communication system, the method comprising the steps of:

a) receiving received signals each of which includes a pilot channel signal and a traffic channel signal, demodulating the received signals to generate demodulated signals, and outputting the demodulated user signals;

b) estimating channel parameters for each of the mobile stations based on the pilot channel signals transmitted from the mobile stations, and generating estimated channel parameters;

c) delaying the received signal and outputting a delayed signal which is delayed in one symbol from the received signal;

d) generating interference signals based on the demodulated user signals and the estimated channel parameters, removing interference signals from the delayed signals, and outputting interference-cancelled-signals in which the interference signals are removed; and

e) demodulating the interference-cancelled-signals and outputting demodulated signals,

wherein each of the channel parameters includes an amplitude distortion and a phase distortion.