Spread spectrum communication system

• US 5,432,814 A
• Filed: 01/24/1994
• Issued: 07/11/1995
• Est. Priority Date: 06/08/1993
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Hasegawa, Takaaki
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US08/185,053
• Time in Patent Office: 533 Days
• Field of Search: 375/1, 380/34, 370/18
• US Class Current: 375/133
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04J 13/0074 Code shifting or hopping

Abstract

A spread spectrum communication system in which a spectrum of a communication signal is spread by using a spreading signal includes PN code generators for generating a plurality of pseudo noise codes which differ from each other, and a selector for selecting the pseudo noise codes generated by the PN code generators in accordance with a predetermined hopping pattern, the pseudo noise codes selected by the selector being used as the spreading signal.

Claims

1. An apparatus, comprising:

PN code generating means for generating a plurality of pseudonoise codes which differ from each other; and

selecting means for selecting the pseudonoise codes in accordance with a predetermined hopping pattern, the pseudonoise codes selected by said selecting means being used as a spreading signal for a spread spectrum communication device.

2. The apparatus as claimed in claim 1, wherein said selecting means comprises:

switching means for switching the pseudonoise codes supplied from said PN generating means; and

control means, connected to said switching means, for controlling said switching means in accordance with the predetermined hopping pattern.

3. The apparatus as claimed in claim 1, wherein said selecting means selects N pseudonoise codes from among said plurality of pseudonoise codes for each bit of information data, where N is an integer greater than 1.

4. The apparatus as claimed in claim 3 further comprising:

first decision means for deciding a data value in each of the N pseudonoise codes and for obtaining N decision values; and

second decision means for selecting, as the data value, a decision value which is in the majority from among the N decision value.

5. The apparatus as claimed in claim 4, wherein N is an odd number equal to or greater than 3.

6. The apparatus as claimed in claim 1, wherein said PN generating means has memory means for storing said plurality of pseudonoise codes and wherein said selecting means has means for reading out the pseudonoise codes from said memory means in accordance with the predetermined hopping pattern.

7. The apparatus claimed in claim 1, further comprising:

a transmitter, connected to the selecting means, for transmitting a signal based on the spreading signal; and

a receiver including;

matched filters for processing a signal corresponding to a received signal, each of said matching filters corresponding to one of said plurality of pseudonoise codes; and

selecting means for carrying out a switching control of said matched filters in accordance with the predetermined hopping pattern,

wherein said received signal corresponds to said transmitted signal.

8. An apparatus according to claim 7, further comprising:

a power amplifier connected to the mixer.

9. An apparatus according to claim 8, further comprising:

a frequency converter, connected between the mixer and the power amplifier, for converting the frequency modulated signal output from the mixer to a signal having a frequency of a carrier.

10. An apparatus according to claim 9, further comprising:

an antenna connected to an output of the power amplifier.

11. An apparatus as claimed in claim 1, further comprising:

a mixer for combining the spreading signal with data items to generate a frequency modulated signal.

12. An apparatus according to claim 1, further comprising:

receiving means for receiving a signal which is combined with one of said pseudonoise codes selected by the selecting means in order to decode the received signal.

13. An apparatus according to claim 1, wherein said selecting means comprises a hopping controller for generating said predetermined hopping pattern, said hopping controller generating the predetermined hopping pattern independent of data to be transmitted.