METHOD FOR DATA COMMUNICATION VIA A VOICE CHANNEL OF A WIRELESS COMMUNICATION NETWORK

• US 20070258398A1
• Filed: 10/31/2006
• Published: 11/08/2007
• Est. Priority Date: 10/24/2005
• Status: Active Grant

• Current Assignee: General Motors LLC (General Motors Company)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Surti, Iqbal, Chesnutt, Elizabeth, Madhavan, Sethu, Yin, Jijun
• Granted Patent: US 8,194,779 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04L 27/2071 in which the data are represented by the carrier phase, e.g. systems with differential coding
• CPC Class Codes: H04L 27/2075 in which the data are represented by the change in carrier phase
• CPC Class Codes: H04L 27/2331 wherein the received signal is demodulated using one or more delayed versions of itself
• CPC Class Codes: H04L 27/36 Modulator circuits; Transmitter circuits

Abstract

A system and method for data communication over a cellular communications network that allows the transmission of digital data over a voice channel using a vocoder that operates in different modes depending upon characteristics of the inputted signal it receives. To prepare the digital data for transmission, one or more carrier signals are encoded with the digital data using one of a number of modulation schemes that utilize differential phase shift keying to give the modulated carrier signal certain periodicity and energy characteristics that allow it to be transmitted by the vocoder at full rate. The modulation schemes include DPSK using either a single or multiple frequency carriers, combined FSK-DPSK modulation, combined ASK-DPSK, as well as PSK with a phase tracker in the demodulator. These modulation schemes permit data communication via a CDMA, GSM, or other type of voice traffic channel at a low bit error rate.

Claims

1. A method of communicating digital data via a wireless telecommunications network, comprising the steps of:

modulating one or more carrier signals with digital data using differential phase shift keying modulation of the one or more carrier signals, thereby producing a modulated carrier signal;

transmitting the modulated carrier signal across a voice channel of a wireless telecommunications network;

receiving the modulated carrier signal transmitted via the wireless telecommunications network; and

demodulating the received modulated carrier signal back into the digital data.

2. The method of claim 1, wherein the modulating step further comprises modulating a single frequency carrier signal at a selected bit rate with the digital data using differential binary phase shift keying modulation.

3. The method of claim 2, wherein the bit rate is within the range of 250 bits/sec to 3,000 bits/sec, and the carrier frequency is within the range of 400 Hz to 2,500 Hz.

4. The method of claim 1, wherein the modulating step further comprises generating the modulated carrier signal as a composite modulated carrier signal by carrying out the steps of:

modulating a plurality of carrier signals, each carrier signal having a different frequency and being modulated with a portion of the digital data using differential phase shift keying modulation; and

combining the plurality of modulated carrier signals into a composite modulated carrier signal.

5. The method of claim 1, wherein the modulating step further comprises generating the modulated carrier signal as a composite modulated carrier signal by carrying out the steps of:

modulating a first carrier signal having a first frequency with a portion of the digital data using differential binary phase shift keying modulation;

modulating a second carrier signal having a second frequency with the remainder of the digital data using differential binary phase shift keying modulation; and

combining the two modulated carrier signals into a composite modulated carrier signal.

6. The method of claim 1, wherein the modulating step comprises modulating a carrier signal using both frequency shift keying modulation and differential phase shift keying modulation.

7. The method of claim 6, wherein the modulating step further comprises generating the modulated carrier signal by the steps of:

(a) generating an FSK modulated carrier signal by modulating the carrier signal with a portion of the digital data using frequency shift keying modulation; and

(b) modulating the FSK modulated carrier signal with the remainder of the digital data using differential phase shift keying modulation.

8. The method of claim 7, wherein the differential phase shift keying modulation comprises differential binary phase shift keying modulation.

9. The method of claim 1, wherein the modulating step comprises modulating a carrier signal using both amplitude shift keying modulation and differential phase shift keying modulation.

10. The method of claim 9, wherein the modulating step further comprises generating the modulated carrier signal by the steps of:

(a) generating an ASK modulated carrier signal by modulating the carrier signal with a portion of the digital data using amplitude shift keying modulation; and

(b) modulating the ASK modulated carrier signal with the remainder of the digital data using differential phase shift keying modulation.

11. A method of communicating digital data via a wireless telecommunications network using a voice encoder that operates in different modes according to a classification of incoming data into categories that include at least voiced, unvoiced, and transient speech, wherein each of the different modes is associated with a coding scheme for encoding the incoming data, the method comprising the steps of:

inputting into the voice encoder a modulated carrier signal having discontinuities and energy characteristics that cause the voice encoder to classify the modulated carrier signal as transient speech;

obtaining an encoded output that is generated by the voice encoder using the inputted modulated carrier signal;

transmitting the encoded output across a voice channel of the wireless telecommunications network;

receiving the encoded output transmitted via the wireless telecommunications network;

generated a decoded modulated carrier signal by decoding the received encoded output using a voice decoder; and

demodulating the decoded modulated carrier signal.

12. The method of claim 11, wherein the method further comprises, prior to the inputting step, the step of generating the modulated carrier signal by modulating one or more carrier signals with digital data using differential phase shift keying modulation of the one or more carrier signals.

13. The method of claim 12, wherein the differential phase shift keying modulation comprises differential binary shift keying modulation.

14. The method of claim 12, wherein the differential phase shift keying modulation comprises differential quadrature shift keying modulation.

15. The method of claim 12, wherein the generating step further comprises generating the modulated carrier signal as a composite modulated carrier signal by carrying out the steps of:

modulating a plurality of carrier signals, each carrier signal having a different frequency and being modulated with a portion of the digital data using differential phase shift keying modulation; and

combining the plurality of modulated carrier signals into a composite modulated carrier signal.

16. The method of claim 12, wherein the generating step further comprises generating the modulated carrier signal as a composite modulated carrier signal by carrying out the steps of:

modulating a first carrier signal having a first frequency with a portion of the digital data using differential binary phase shift keying modulation;

modulating a second carrier signal having a second frequency with the remainder of the digital data using differential binary phase shift keying modulation; and

combining the two modulated carrier signals into a composite modulated carrier signal.

17. The method of claim 16, wherein the steps of modulating the first and second carrier signals further comprise separating the digital data into alternating first and second groups of data, modulating the first carrier signal with the first group of data, and modulating the second carrier signal with the second group of data.

18. The method of claim 11, wherein the method further comprises, prior to the inputting step, the step of generating the modulated carrier signal by modulating a carrier signal using both frequency shift keying modulation and differential phase shift keying modulation.

19. The method of claim 11, wherein the method further comprises, prior to the inputting step, the step of generating the modulated carrier signal by modulating a carrier signal using both amplitude shift keying modulation and differential phase shift keying modulation.

20. The method of claim 11, wherein the method further comprises, prior to the inputting step, the step of generating the modulated carrier signal by modulating one or more carrier signals with digital data using phase shift keying modulation of the one or more carrier signals, and wherein the demodulating step comprises demodulating the decoded modulated carrier signal using a phase tracker.

21. A method of wirelessly transmitting digital data using an EVRC-B vocoder, the method comprising the steps of:

encoding digital data by modulating at least one carrier signal with the digital data and producing therefrom a modulated carrier signal having discontinuities and energy characteristics that cause the vocoder to classify the modulated carrier signal as transient speech;

inputting the modulated carrier signal into an EVRC-B vocoder;

obtaining an encoded output from the vocoder; and

transmitting the encoded output via an antenna.

22. The method of claim 21, wherein the encoding step further comprises performing binary differential phase shift keying (DBPSK) modulation of one or more carrier signals using the digital data.

23. The method of claim 22, wherein the step of performing DBPSK modulation further comprises modulating a single frequency carrier signal at a selected bit rate with the digital data using differential binary phase shift keying modulation.

24. The method of claim 23, wherein the bit rate is within the range of 250 bits/sec to 3,000 bits/sec, and the carrier frequency is within the range of 400 Hz to 2,500 Hz.

25. The method of claim 21, wherein the encoding step further comprises generating the modulated carrier signal as a composite modulated carrier signal by carrying out the steps of:

modulating a plurality of carrier signals, each carrier signal having a different frequency and being modulated with a portion of the digital data using differential phase shift keying modulation; and

combining the plurality of modulated carrier signals into a composite modulated carrier signal.

26. The method of claim 21, wherein the encoding step further comprises generating the modulated carrier signal as a composite modulated carrier signal by carrying out the steps of:

modulating a first carrier signal having a first frequency with a portion of the digital data using differential binary phase shift keying modulation;

modulating a second carrier signal having a second frequency with the remainder of the digital data using differential binary phase shift keying modulation; and

combining the two modulated carrier signals into a composite modulated carrier signal.

27. The method of claim 21, wherein the encoding step comprises modulating a carrier signal using both frequency shift keying modulation and differential phase shift keying modulation.

28. The method of claim 27, wherein the modulating step further comprises generating the modulated carrier signal by the steps of:

(a) generating an FSK modulated carrier signal by modulating the carrier signal with a portion of the digital data using frequency shift keying modulation; and

(b) modulating the FSK modulated carrier signal with the remainder of the digital data using differential phase shift keying modulation.

29. The method of claim 21, wherein the encoding step further comprises conditioning the carrier signal phase shifts.

30. A method of communicating digital data via a wireless telecommunications network using a vocoder that encodes and transmits an incoming data signal at one or more of a plurality of different rates including a full rate and one or more lesser rates, wherein the rate used by the vocoder to encode and transmit the incoming data signal is dependent at least in part upon the periodicity of the incoming data signal and characteristics of the energy contained in the incoming data signal, wherein the method comprises the steps of:

modulating one or more carrier signals using digital data such that a resulting modulated carrier signal is produced having the following characteristics;

a) NACF_sf2<

UNVOICEDTH;

b) bER>

0; and

c) vER2>

−

15;

where;

NACF_sf2 is a second subframe normalized autocorrelation function and UNVOICEDTH is a threshold value based on a determined signal to noise ratio;

bER is a frequency band energy ratio determined according to the equation

$\mathrm{bER}={\log }_2<br><br>\frac{\mathrm{EL}}{\mathrm{EH}},$

with EL being the amount of energy contained in a lower frequency band of 0-2 kHz, and EH being the amount of energy contained in a higher frequency band of 2-4 kHz; and

vER2 is determined according to the equation

$\mathrm{vER}<br><br>\text{\hspace{1em}<br><br>}<br><br>2=\mathrm{MIN}<br><br>\left(20,10*{\log }_{10}<br><br>\frac{E}{\mathrm{vEav}}\right),$

 

with E being the energy of a current frame of the modulated carrier signal and vEav being the average energy over three previous voiced frames of the modulated carrier signal;

transmitting the modulated carrier signal across a voice channel of a wireless telecommunications network;

receiving the modulated carrier signal transmitted via the wireless telecommunications network; and

demodulating the received modulated carrier signal back into the digital data.