PN sequence identifying device in CDMA communication system

• US 6,603,735 B1
• Filed: 08/30/1999
• Issued: 08/05/2003
• Est. Priority Date: 08/29/1998
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Hyun-Kyu, Park, Su-Won
• Primary Examiner(s): Yao, Kwang Bin
• Assistant Examiner(s): Emdadi, Kamran
• Application Number:
  US09/386,062
• Time in Patent Office: 1,436 Days
• Field of Search: 370/209, 370/335, 370/342, 370/441, 370/204, 370/205, 370/206, 370/207, 370/208, 370/210, 370/211, 375/130, 375/140, 375/146, 375/147, 375/149
• US Class Current: 370/208
• CPC Class Codes: H04B 1/708 Parallel implementation
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 2201/70702 Intercell-related aspects

Abstract

A PN sequence identifying device in a receiver in an asynchronous CDMA communication system. The receiver receives first OGCs on a primary sync channel and second OGCs on a secondary sync channel synchronized with the primary sync channel symbol by symbol. In the PN sequence identifying device, a first OGC detector detects the first OGCs and obtains a first symbol energy. A first synchronizer receives the first symbol energy, synchronizes chips, symbols, and slots, and outputs a first sync signal. A second OGC detector, upon reception of the first sync signal, detects the second OGCs each time the first sync signal is received, and obtains second symbol energies in base station identifying group units. A hopping pattern generator compares the first symbol energy with the second symbol energies, determines whether null signs are in the second OGCs, determines the order of the null signs if the null signs are present, and generates a hopping pattern of the second OGCs. A second synchronizer synchronizes frames based on the hopping pattern and outputs a second sync signal. A PN sequence generator receives the first and second signals and the hopping pattern and generates a PN sequence.

Claims

1. In an asynchronous CDMA communication system, which transmits and receives first orthogonal Gold codes (OGCs) on a primary sync channel and second OGCs on a secondary sync channel synchronized with the primary sync channel symbol by symbol, comprising:

a transmitter, comprising;

a PN sequence generating device for generating a PN sequence having one of the OGCs replaced with a null sign; and

a receiver, comprising;

a first OGC detector for detecting the first OGCs and obtaining a first symbol energy;

a first synchronizer for receiving the first symbol energy, synchronizing chips, symbols, and slots, and outputting a first sync signal;

a second OGC detector, upon reception of the first sync signal, detects the second OGCs each time the first sync signal is received, and obtaining second symbol energies in base station identifying group units;

a hopping pattern generator for comparing the first symbol energy with the second symbol energies, determining whether null signs are in the second OGCs, determining the order of the null signs if the null signs are present, and generating a hopping pattern of the second OGCs;

a second synchronizer for synchronizing frames based on the hopping pattern and outputting a second sync signal; and

a PN sequence generator for receiving the first and second signals and the hopping pattern and generating a PN sequence.

2. The device of claim 1, wherein the first OGC detector comprises:

a matched filter for detecting the first OGCs received on the primary sync channel; and

a first squarer for calculating the symbol energy of the first OGCs.

3. The device of claim 1, wherein the second OGC detector comprises:

a plurality of correlators for detecting second OGCs except for the null signs among the second OGCs received on the secondary sync channel; and

a plurality of second squarers for calculating the symbol energies of the second OGCs received from the correlators.

4. The device of claim 1, wherein the hopping pattern generator comprises:

a hopping pattern estimator for determining whether null signs exist, comparing the first symbol energy with each of the second symbol energies if the null signs are present, determining the order of the null signs, and estimating a hopping pattern of the second OGCs; and

a hopping pattern determiner for storing a comma free code table, comparing the estimated hopping pattern with the comma free code table, and determining a hopping pattern.

5. The device of claim 4, wherein the hopping pattern estimator comprises:

a maximum value detector for detecting the highest of the second symbol energies, and sequentially storing the highest symbol energy and the number of the correlator with the highest symbol energy;

an amplifier for amplifying the first symbol energy by the reciprocal of the ratio of the transmission power of the first symbol energy to that of the stored second symbol energy; and

a comparator for determining the presence and order of null signs by comparing the amplified first symbol energy with the stored second symbol energy, and generating an estimated hopping pattern.

6. The device of claim 4, wherein the hopping pattern determiner comprises:

a comma free code table for storing comma free codes; and

a hopping pattern determiner for receiving the estimated hopping pattern, comparing the estimated hopping pattern with the comma free code table, determining a hopping pattern, and outputting the hopping pattern to the second synchronizer and the PN sequence generator.

7. The device of claim 5, wherein the hopping pattern determiner comprises:

a comma free code table for storing comma free codes; and

a hopping pattern determiner for receiving the estimated hopping pattern, comparing the estimated hopping pattern with the comma free code table, determining a hopping pattern, and outputting the hopping pattern to the second synchronizer and the PN sequence generator.

8. The device of claim 5, wherein the comparator compares the first symbol energy with each of the second symbol energies in the detected order and inserts the second symbol energy smaller than the first symbol energy before the number of the correlator which outputs the second symbol energy.

9. The device of claim 6, further comprising a first switch for blocking information applied from the hopping pattern estimator to the hopping pattern determiner upon generation of the second sync signal.

10. The device of claim 7, further comprising a first switch for blocking information applied from the hopping pattern estimator to the hopping pattern determiner upon generation of the second sync signal.