Patent
Method and apparatus for enhanced communication capability while maintaining standard channel modulation compatibility
| العنوان: | Method and apparatus for enhanced communication capability while maintaining standard channel modulation compatibility |
|---|---|
| Patent Number: | 5,987,068 |
| تاريخ النشر: | November 16, 1999 |
| Appl. No: | 08/744,913 |
| Application Filed: | November 08, 1996 |
| مستخلص: | In a radio communication system (100), enhanced communication capability is provided while maintaining standard channel modulation compatibility. At a transmitter (110, 200, 600), a first information signal is generated from data according to a predefined standard modulation scheme (212, 613). A second information signal is generated from data that provides supplemental information to the standard modulated data (213, 616). For transmission, the first and second information signals are combined into a composite signal (214, 619) that represents the first information signal when interpreted according to the predefined standard modulation scheme. |
| Inventors: | Cassia, Simon Hugh (Chandlers Ford, GBX); Aftelak, Andrew John (Thatcham, GBX); Tan, Boon Tiong (Kent Ridge, SGX); Lee, Kwan Yee (Basingstoke, GBX) |
| Assignees: | Motorola, Inc. (Schaumburg, IL) |
| Claim: | What is claimed is |
| Claim: | 1. A method for providing enhanced communication capability in a radio communication system while maintaining standard channel modulation compatibility, the radio communication system having a standard receiver, an enhanced transmitter, and an enhanced receiver, and a predefined modulation scheme that completely defines a standard for communications among the transmitter and receivers, the method comprising the steps of |
| Claim: | at the enhanced transmitter |
| Claim: | generating a first information signal from first data according to the predefined modulation scheme; |
| Claim: | generating a second information signal from second data that provides supplemental information to the first data, wherein the second information signal is modulated time coincidentally with the first information signal; |
| Claim: | combining the first and second information signal into a composite signal that represents only the first information signal when interpreted, according to the predefined modulation scheme, by the standard receiver, but that represents a combination of the first and second information signals when interpreted by the enhanced receiver; and |
| Claim: | transmitting the composite signal on a radio frequency communication channel. |
| Claim: | 2. The method of claim 1, further characterized in that |
| Claim: | the step of generating a first information signal comprises the step of modulating the first information signal on at least one carrier signal; and |
| Claim: | the step of combining comprises the step of modulating the second information signal using the first information signal as a carrier signal. |
| Claim: | 3. The method of claim 2, further characterized in that the step of modulating the first information signal comprises |
| Claim: | modulating the first information signal using .pi./4 differential quadrature phase shift keying (DQPSK). |
| Claim: | 4. The method of claim 3, further characterized in that the step of modulating the second information signal comprises |
| Claim: | modulating the second information signal using an amplitude modifier applied to the first information signal. |
| Claim: | 5. The method of claim 3, further characterized in that the step of modulating the second information signal comprises |
| Claim: | modulating the second information signal using a phase modifier applied to the first information signal. |
| Claim: | 6. The method of claim 3, further characterized by the step of, at the transmitter |
| Claim: | filtering the composite signal with a root raised cosine low-pass filter before the step of transmitting. |
| Claim: | 7. The method of claim 1, further characterized in that |
| Claim: | the step of generating a second information signal comprises the step of |
| Claim: | modulating the second information signal substantially orthogonal to the first information signal. |
| Claim: | 8. The method of claim 1, further characterized in that |
| Claim: | the step of generating a first information signal comprises the steps of |
| Claim: | modulating the first information signal using .pi./4 differential quadrature phase shift keying (DQPSK) to provide a modulated first information signal; |
| Claim: | filtering the modulated first information signal using a root raised cosine low-pass filter to provide a filtered modulated first information signal; |
| Claim: | modulating the second information signal using an orthogonal pulse shape filter to provide a filtered modulated second information signal substantially orthogonal to the filtered modulated first information signal; and |
| Claim: | the step of combining comprises the step of |
| Claim: | combining the filtered modulated first information signal with the filtered modulated second information signal to produce the composite signal. |
| Claim: | 9. The method of claim 8, further characterized in that |
| Claim: | the step of modulating the first information signal comprises the steps of |
| Claim: | mapping bit pairs representing the first data onto phase changes of the at least one carrier signal according to .pi./4 DQPSK modulation; |
| Claim: | differentially encoding the phase changes to a particular symbol value; and |
| Claim: | the step of modulating the second information signal comprises the step of |
| Claim: | differentially encoding data bits representing the supplemental information. |
| Claim: | 10. The method of claim 1, further characterized by the steps of |
| Claim: | at the enhanced receiver |
| Claim: | receiving the composite signal; |
| Claim: | recovering the first data from the composite signal; |
| Claim: | recovering the second data from the composite signal; and |
| Claim: | combining the second data with the first data to enhance quality of information provided by the first data. |
| Claim: | 11. The method of claim 10, further characterized in that |
| Claim: | the step of recovering the first data comprises the steps of |
| Claim: | filtering the composite signal using root raised cosine low-pass filtering to provide a first filtered composite signal; |
| Claim: | decoding the first filtered composite signal with a .pi./4 DQPSK differential decoder; |
| Claim: | generating the first data with a first symbol detector; |
| Claim: | the step of recovering the second data comprises the steps of |
| Claim: | filtering the composite signal using root raised cosine low-pass filtering to provide a second filtered composite signal; |
| Claim: | decoding he second filtered composite signal with a differential decoder; |
| Claim: | generating the second data from the second filtered composite signal with a second symbol detector. |
| Claim: | 12. The method of claim 10, further characterized in that |
| Claim: | filtering the composite signal with an orthogonal pulse shape filter to provide a second filtered composite signal; |
| Claim: | decoding the second filtered composite signal with a differential decoder; |
| Claim: | 13. The method of claim 10, further characterized in that the first data comprises encoded speech. |
| Claim: | 14. The method of claim 13, further characterized in that the second data comprises speech parameters that support enhancement of the encoded speech. |
| Claim: | 15. The method of claim 10 or 13, further characterized in that the second data comprises error mitigation information for the first data. |
| Claim: | 16. A radio communication system having a plurality of transmitters and receivers, and providing for standard communications using a predefined channel modulation scheme among the plurality of transmitters and receivers, and for enhanced communications between selected units of the plurality of transmitters and receivers while maintaining standard channel modulation compatibility, the plurality of transmitters and receivers comprising |
| Claim: | a standard receiver; |
| Claim: | an enhanced receiver; and |
| Claim: | an enhanced transmitter apparatus that provides a composite signal to the standard receiver and to the enhanced receiver, such that when interpreted by the standard receiver, the composite signal provides a standard set of information that is complete according to the predefined channel modulation scheme that governs communication among transmitters and receivers in the radio communication system, and when interpreted by the enhanced receiver, contains supplemental information not affecting the standard receiver but used by the enhanced receiver for enhanced communications, the transmitter apparatus, comprising |
| Claim: | means for modulating a first symbol set from first data to provide a first modulated signal according to the predefined channel modulation scheme; and |
| Claim: | means, coupled to said first modulated signal, for superimposing a second modulated signal from second data on said first modulated signal to provide the composite signal that represents the first modulated signal within permissible variation, according to the predefined channel modulation scheme, wherein the second data supplements the first data. |
| Claim: | 17. The radio communication system of claim 16, further characterized in that the means for modulating comprises a .pi./4 DQPSK differential encoder. |
| Claim: | 18. The radio communication system of claim 17, further characterized in that the means for superimposing comprises means for varying amplitude of the first modulated signal to modulate the second modulated signal. |
| Claim: | 19. The radio communication system of claim 17, further characterized in that the means for superimposing comprises means for varying phase of the first modulated signal to modulate the second modulated signal. |
| Claim: | 20. The radio communication system of claim 16, further characterized in that the means for superimposing comprises means for generating the second modulated signal orthogonal to, and time coincidental with, the first modulated signal. |
| Claim: | 21. The radio communication system of claim 20, wherein the transmitter apparatus further comprises |
| Claim: | apparatus for generating the second modulated signal, comprising |
| Claim: | differential encoder coupled to the second data and providing second encoded data; |
| Claim: | an orthogonal pulse shape filter coupled to the second encoded data and providing second filtered data, wherein the second modulated signal is derived from the second filtered data; and |
| Claim: | wherein |
| Claim: | the means for modulating comprises |
| Claim: | a .pi./4 DQPSK differential encoder coupled to the first data and providing first encoded data in response to the first data; |
| Claim: | a root raised cosine low-pass filter coupled to the first encoded data and providing first filtered data in response to the first encoded data, wherein the first modulated signal is derived from the first filtered data; and |
| Claim: | the means for superimposing comprises |
| Claim: | a combiner coupled to the first modulated signal and to the second modulated signal and providing the composite signal as an output. |
| Claim: | 22. The radio communication system of claim 16, further characterized in that the second data comprises error mitigation information for the first data. |
| Current U.S. Class: | 375/281; 375/283; 375/285; 375/308; 375/331; 455/501; 455/102; 455/132; 455/143; 329/316; 329/348; 332/108; 332/119; 332/151 |
| Current International Class: | H04L 2732 |
| Patent References Cited: | 4211996 July 1980 Nakamura 4481640 November 1984 Chow et al. 4663768 May 1987 Ryu 4731800 March 1988 Motley et al. 5157693 October 1992 Lemersal, Jr. et al. 5222103 June 1993 Gross 5233630 August 1993 Wolf |
| Primary Examiner: | Le, Amanda |
| Attorney, Agent or Firm: | Fuller, Andrew S. |
| رقم الانضمام: | edspgr.05987068 |
| قاعدة البيانات: | USPTO Patent Grants |
| الوصف غير متاح. |