Mobile communication system capable of transmitting and receiving a radio signal obtained by TDMA and CDMA without interference

• US 5,511,068 A
• Filed: 12/06/1994
• Issued: 04/23/1996
• Est. Priority Date: 12/08/1993
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Sato, Toshifumi
• Primary Examiner(s): MARCELO, MELVIN C
• Application Number:
  US08/349,885
• Time in Patent Office: 504 Days
• Field of Search: 370/18, 370/50, 370/84, 375/201, 375/203, 375/205, 375/207, 375/231
• US Class Current: 370/335
• CPC Class Codes: H04B 7/2618 using hybrid code-time division multiple access [CDMA-TDMA]
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713

Abstract

In a communication system from a mobile station to a base station, a transmitter of the mobile station subjects a sequence of transmission signals to both of time division multiple access (TDMA) and code division multiple access (CDMA) to produce a radio output signal located in a time slot of a frame. The radio output signal obtained by the TDMA and CDMA is filtered or inversely spread to remove interference and noise from the radio output signal by the use of an adaptive filter which has taps controlled by an adaptive controller.

Claims

1. A mobile station for use in a radio communication system to produce a radio output signal, said mobile station comprising a transmitter operable in response to a sequence of transmission signals which is divisible into a succession of frames and which has a predetermined rate, said transmitter comprising:

rate converting means supplied with said transmission signal sequence for successively rate converting said transmission signal sequence into a sequence of rate converted signals which has a second rate higher than said first rate and which lasts for a time slot shorter than each of said frames;

spread code producing means producing a preselected spread code which is assigned to said transmitter and which is divided into a plurality of chips;

code division multiple access means supplied with said preselected spread code and said rate converted signal sequence for carrying out code division multiple access operation of said rate converted signal sequence in accordance with said preselected spread code to produce a sequence of spread signals which is related to said preselected spread code; and

means producing said spread signal sequence as said radio output signal by allocating said spread signal sequence to at least one specific time slot predetermined for said transmitter.

2. A mobile station as claimed in claim 1, wherein said code division multiple access means comprises:

a multiplier for multiplying said rate converted signal sequence by said preselected spread code to produce a sequence of product signals representative of products of said rate converted signal sequence and said preselected spread code; and

means for producing said product signals as said spread signal sequence.

3. A mobile station as claimed in claim 1, each of said frames being divided into first through L-th ones of the time slots where L is an integer greater than unity, said mobile station being assigned with a predetermined one of the first through the L-th time slots, wherein said preselected spread code has a spread factor of M where M is an integer greater than unity and a chip rate equal to a product of L and M.

4. A mobile station as claimed in claim 1, each of said frames being divided into a plurality of the time slots, said mobile station being assigned with a plurality of the time slots.

5. A mobile station as claimed in claim 1, wherein said rate converting means is a rate converter.

6. A mobile station as claimed in claim 1, wherein said spread code producing means is a spread code generator.

7. A communication system comprising a transmitter and a receiver, said transmitter being operable in response to a sequence of transmission signals to produce a radio output signal, said transmission signal sequence being divisible into a succession of frames and having a first rate, said transmitter comprising:

rate converting means supplied with said transmission signal sequence for successively rate converting said transmission signal sequence into a sequence of rate converted signals which has a second rate higher than said first rate and which lasts for a time slot shorter than each of said frames;

spread code producing means producing a preselected spread code assigned to said transmitter and divided into a plurality of chips produced at a predetermined chip rate;

code division multiple access means supplied with said preselected spread code and said rate converted signal sequence for carrying out code division multiple access operation of said rate converted signal sequence in accordance with said preselected spread code to produce a sequence of spread signals which is related to said preselected spread code; and

means for producing said spread signal sequence as said radio output signal by allocating said spread signal sequence to at least one specific time slot predetermined for said transmitter.

8. A communication system as claimed in claim 7, said receiver being given said radio output signal as a reception input signal which conveys said spread signal sequence, to produce a sequence of reception output signals, said receiver comprising:

demodulating means supplied with said reception input signal for demodulating said reception input signal into a sequence of baseband signals concerned with said spread signal sequence;

adaptive filter means coupled to said demodulating means for adaptively filtering said baseband signal sequence to produce a sequence of reproduced signals corresponding to said transmission signal sequence; and

output means producing said reproduced signal sequence as said reception output signal sequence.

9. A communication system as claimed in claim 8, wherein:

said receiver further comprises;

a timing generator for producing first and second clock sequences having first and second clock rates which are higher than said chip rate and equal to said second rate, respectively; and

an adaptive controller coupled to said adaptive filter means and said timing generator for controlling said adaptive filter means by a control signal to make said adaptive filter means produce said reproduced signal sequence;

said adaptive filter means comprises;

a first sampler, which is supplied with said baseband signal sequence and which is operable in response to said first clock sequence, for sampling said baseband signal sequence at said first clock rate into a sequence of sampled signals;

a shift register having a plurality of states and taps derived from the respective stages for successively storing said sample signal sequence to produce stored sampled signals as tap output signals through the respective taps;

multiplying means multiplying said tap output signals by said control signal to produce a plurality of product signals representative of products of said control signal and said tap output signals;

summing means for summing up said product signals into a sum signal representative of a sum of said product signals; and

a second sampler, which is supplied with said sum signal and said second clock sequence, for sampling said product signals at said second clock rate to produce said reproduced signal sequence.

10. A communication system as claimed in claim 9, wherein said timing generator is supplied with said reception output signal and said reproduced signal sequence and is operated in accordance with predetermined algorithm to produce tap coefficient signals as said control signal such that an error signal becomes minimum between said reception output signal sequence and said reproduced signal sequence.

11. A communication system as claimed in claim 8, wherein:

said receiver further comprises;

a timing generator for producing first and second clock sequences having first and second clock rates which are higher than said chip rate and equal to said second rate, respectively; and

an adaptive controller coupled to said adaptive filter means and said timing generator for controlling said adaptive filter means by a control signal to make said adaptive filter means produce said reproduced signal sequence;

said adaptive filter means comprises;

a first sampler, which is supplied with said baseband signal sequence and which is operable in response to said first clock sequence, for sampling said baseband signal sequence at said first clock rate into a sequence of sampled signals;

rearranging means rearranging said sampled signal sequence into a sequence of rearranged signals;

a shift register having a plurality of stages and taps derived from the respective stages for successively storing said rearranged signal sequence to produce stored rearranged signals as tap output signals through the respective taps;

multiplying means multiplying said tap output signals by said control signal to produce a plurality of product signals representative of products of said control signal and said tap output signals;

summing means for summing up said product signals into a sum signal representative of a sum of said product signals; and

a second sampler, which is supplied with said sum signal and said second clock sequence, for sampling said product signals at said second clock rate to produce said reproduced signal sequence.

12. A communication system as claimed in claim 11, wherein said adaptive controller is supplied with said reception output signal sequence and said reproduced signal sequence and is operated in accordance with predetermined algorithm to produce tap coefficient signals as said control signal such that an error signal becomes minimum between said reception output signal sequence and said reproduced signal sequence.

13. A communication system as claimed in claim 12, wherein said adaptive controller is further supplied with said tap output signals which includes a training signal and initially trains said adaptive filter means by the use of said training signal.

14. A communication system as claimed in claim 13, wherein said training signal is included in said rearranged signal sequence and is initially given to said shift register by rearranging said sampled signal sequence by said rearranging means.

15. A communication system as claimed in claim 14, wherein said training signal in said sampled signal sequence is located between information signals carried by said reception input signal.

16. A communication system as claimed in claim 8, wherein said demodulating means is a demodulator.

17. A communication system as claimed in claim 8, wherein said adaptive filter means is an adaptive filter.

18. A communication system as claimed in claim 7, wherein said rate converting means is a rate converter.

19. A communication system as claimed in claim 7, wherein said spread code producing means is a spread code generator.

20. A receiver for use in a radio communication system to produce a sequence of reception output signals in response to a radio input signal which is divisible into a succession of frames and which conveys a spread signal sequence in a predetermined time slot formed by dividing each frame, said receiver comprising:

demodulating means being provided with said radio input signal for demodulating said radio input signal into a sequence of baseband signals concerned with said spread signal sequence;

adaptive filter means, which is coupled to said demodulating means and which has a plurality of taps for adaptively filtering said baseband signal sequence to produce a sequence of reproduced signals by adaptively controlling said taps; and

output means producing said reproducing signal sequence as said reception output signal sequence.

21. A receiver as claimed in claim 20, wherein said demodulating means is a demodulator.

22. A receiver as claimed in claim 20, wherein said adaptive filter means is an adaptive filter.