Multi-channel spread spectrum communications system

• US 7,242,663 B2
• Filed: 06/19/2002
• Issued: 07/10/2007
• Est. Priority Date: 06/19/2002
• Status: Expired due to Fees

• Current Assignee: George L. Yang
• Original Assignee: George L. Yang
• Inventors: Yang, George L.
• Primary Examiner(s): Kizou; Hassan
• Assistant Examiner(s): O CONNOR, BRIAN T
• Application Number:
  US10/174,768
• Publication Number:
  US 20030235148A1
• Time in Patent Office: 1,847 Days
• Field of Search: 370/206, 370/335, 370/342, 370/208, 370/329, 375/140, 375/141, 375/143, 375/146, 375/147, 375/152
• US Class Current: 370/206
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04J 13/0077 Multicode, e.g. multiple codes assigned to one user

Abstract

A multi-channel spread spectrum communications system utilizes the combination of spreading codes to represent and transfer information. On the transmitter side, every block of data bits is divided into two sub-blocks of data bits. One sub-block is mapped to a number of spreading codes, while another sub-block is separated further into several smaller sub-blocks with each of them mapped into an M-ary phase. Each selected spreading code is modulated by the corresponding M-ary phase. On the receiver side, first determine the most likely transmitted spreading codes and their respective phases, then reverse map the set of estimated transmitted spreading codes into a block of bits and each of the phases into another block of data bits, and finally combine all these blocks to a single block of data bits.

Claims

1. A communication system having a plurality of transmittable signals with each subset of said plurality of transmittable signals is an element of a power set of said plurality of transmittable signals, said system comprising:

a mapping device at a transmitter for mapping a first block of data bits into an element of said power set according to a predefined mapping scheme, wherein said transmitter transmits said element into a transmission link;

a detection device at a receiver for determining a likely transmitted element of said power set from said transmission link; and

a reverse mapping device at said receiver for reversely mapping said likely transmitted element into a second block of data bits according to said predefined mapping scheme,

whereby said first block of data bits is identical to said second block of data bits in a noise-free and interference-free environment.

2. The communication system as in claim 1, wherein said plurality of transmittable signals is a plurality of spreading codes.

3. The communication system as in claim 1, wherein said plurality of transmittable signals is a plurality of signals centered at different frequencies.

4. The communication system as in claim 1, wherein said plurality of transmittable signals is a plurality of signals transmitted at different time slots.

5. The communication system as in claim 1, wherein said plurality of transmittable signals are a plurality of signals different from each other at least at one category selected from a group consisting of frequency and time slot.

6. The communication system as in claim 1, wherein said plurality of transmittable signals are a plurality of signals different from each other at least at one category selected from a group consisting of orthogonal code, frequency, and time slot.

7. The communication system as in claim 1, wherein each transmittable signal has a same amount of power, said predefined mapping scheme letting a block of data bits having higher probability of usage correspond to an element of said power set with a smaller number of transmittable signals for saving power.

8. The communication system as in claim 1, wherein each element of said power set has a same amount of power, said predefined mapping scheme letting a block of data bits corresponding to an important message be associated with an element of said power set with a smaller number of transmittable signals for increasing probability to detect said important message correctly.

9. The communication system as in claim 1, wherein said predefined mapping scheme specifies a particular subset of said power set, each element of said particular subset comprising a same number of transmittable signals.

10. A communication system having a plurality of orthogonal codes, said system transmitting a block of data bits by sending an element of a power set of said plurality of orthogonal codes over a communication link, wherein said element belongs to a subset of said power set with each element of said subset having a same number of orthogonal codes, said system comprising:

a transmitting subsystem, said transmitting subsystem including,

a first bit separating device for dividing said block of data bits into a first block of data bits and a second block of data bits;

a first mapping device for generating a selecting signal according to said first block of data bits and a predefined mapping scheme;

an orthogonal code selection device for selecting a particular element from said power set according to said selecting signal;

a second bit separating device for dividing said second block of data bits into a plurality of smaller blocks of data bits;

a plurality of second mapping devices with each second mapping device for mapping each smaller block of data bits into a modulating signal;

a plurality of sub-modulators for generating a plurality of modulated signals with each sub-modulator modulating a corresponding orthogonal code of said particular element by a corresponding modulating signal; and

a signal combiner for combining said plurality of modulated signals, and

a receiving subsystem, said receiving subsystem including,

a correlation device for determining energy associated with each orthogonal code;

a detection device for determining most likely a plurality of active orthogonal codes according to energy associated with each orthogonal code and said predefined mapping scheme;

a first reverse mapping device for generating an estimated first block of data bits according to said plurality of active orthogonal codes and said predefined mapping scheme;

a plurality of sub-demodulators for generating a plurality of estimated modulating signals with each sub-modulator demodulating an active orthogonal code;

a plurality of second reverse mapping devices for generating a plurality of estimated smaller blocks of data bits with each second reverse mapping device reversely mapping a corresponding estimated modulating signal;

a first bit combination device for combining said plurality of estimated smaller blocks of data bits into an estimated second block of data bits; and

a second bit combination device for combining said estimated first block of data bits with said estimated second block of data bits to generate estimated block of data bits,

whereby said estimated block of data bits is identical to said block of data bits in a noise-free and interference-free environment.

11. The communication system as in claim 10, wherein each sub-modulator comprises an M-ary PSK modulator and wherein each sub-demodulator comprises an M-ary PSK demodulator.

12. The communication system as in claim 10, wherein each sub-modulator comprises a QAM modulator and wherein each sub-demodulator comprises a QAM demodulator.

13. The communication system as in claim 10, wherein each sub-modulator comprises a PAM modulator and wherein each sub-demodulator comprises a PAM demodulator.

14. A communication system having a plurality of transmittable signals and sending a stream of data bits over a communication link by transmitting a plurality of working elements of a power set of said plurality of transmittable signals, wherein said plurality of working elements are a predefined subset of said power set for conducting transmission, said system comprising:

a mapping scheme for linking each working element with a different first block template, for associating said each working element with a second block template, and for connecting each transmittable signal of said each working element with a corresponding portion of said second block template, wherein said second block template has a plurality of portions with each portion corresponding to a respective transmittable signal of said each working element and with a blocksize determined by number of transmittable signals of said each working element and a modulation scheme to be used, and wherein each first block template has a same blocksize;

a transmitting subsystem, said transmitting subsystem including,

a means for taking a first block of data bits from said stream of data bits with a blocksize being equal to said same blocksize;

a first mapping device for mapping said first block of data bits into an element of said power set according to said mapping scheme;

a means for taking a second block of data bits with a blocksize determined by said mapping scheme and said element;

a bit separation device for separating said second block of data bits into a plurality of smaller blocks of data bits according to said mapping scheme;

a plurality of second mapping device for mapping said plurality of smaller blocks of data bits into a plurality of modulating signals according to said modulation scheme;

a plurality of sub-modulators for modulating each transmittable signal of said element by a corresponding modulating signal to generate a plurality of modulated signals; and

a signal combiner for combining said plurality of modulated signals into a compound signal, wherein said compound signal is transmitted over said communication link;

a receiving subsystem, said receiving subsystem including,

a detection device for determining energy associated with every possible transmittable signal and determining an estimated element of said power set;

a first reverse mapping device for reversely mapping said estimated element into a first estimated block of data bits according to said mapping scheme;

a plurality of sub-demodulators for demodulating each transmittable signal of said estimated element of said power set into a plurality of estimated smaller blocks of data bits;

a first bit combination device for combining said plurality of estimated smaller blocks of data bits into a second estimated block of data bits according to said mapping scheme;

a second bit combination device for combining said first estimated block of data bits and said second estimated block of data bits to generate an estimated block of data bits, whereby said estimated block of data bits is identical to combination of said first block of data bits and said second block of data bits in a noise-free and interference-free environment.

15. The communication system as in claim 14, wherein said plurality of transmittable signals is a plurality of signals centered at different frequencies.

16. The communication system as in claim 14, wherein said plurality of transmittable signals is a plurality of signals transmitted at different time slots.

17. The communication system as in claim 14, wherein said plurality of transmittable signals are a plurality of signals different from each other by at least one category selected from a group consisting of frequency and time slot.

18. The communication system as in claim 14, wherein said plurality of transmittable signals are a plurality of signals different from each other by at least one category selected from a group consisting of orthogonal code, frequency, time slot.

19. The communication system as in claim 14, wherein said predefined mapping scheme lets a block of data bits having higher probability of usage correspond to an element of said power set with a smaller number of transmittable signals for saving power when each transmittable signal has a same amount of power and wherein said predefined mapping scheme lets a block of data bits corresponding to an important message be associated with an element of said power set with a smaller number of transmittable signals for increasing probability to detect said important message correctly when each element of said power set has a same amount of power.

20. The communication system as in claim 14, wherein each modulating device and each demodulating device are for modulating and demodulating respectively a signal belonging to a same category selected from a group consisting of M-ary PSK, M-ary QAM, and M-ary PAM.