RU2496242C2 - System and method for in-band modem for data transmission over digital wireless communication networks - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: system is provided for transmitting information through a speech codec (in-band) such as found in a wireless communication network. A modulator transforms the data into a spectrally noise-like signal based on the mapping of a shaped pulse to predetermined positions within a modulation frame, and the signal is efficiently encoded by a speech codec. A synchronisation sequence provides modulation frame timing at the receiver and is detected based on analysis of a correlation peak pattern. A request/response protocol provides reliable transfer of data using message redundancy, retransmission and/or robust modulation modes dependent on the communication channel conditions.

EFFECT: efficient and quality transmission of data through a speech codec in a communication network.

8 cl, 41 dwg

Description

Priority Claim

Priority claims are made in accordance with the following provisional patent applications: 61 / 059,179, entitled "ROBUST SIGNAL FOR DATA TRANSMISSION OVER IN-BAND VOICE MODEM IN DIGITAL CELLULAR SYSTEMS" filed June 5, 2008, and assigned to its applicant, and explicitly incorporated herein by reference; and 61 / 087,923, entitled "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS (OR CELLULAR) COMMUNICATION NETWORKS", filed August 11, 2008, and assigned to its applicant, and expressly incorporated herein by reference ; and 61/093657, entitled "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS (OR CELLULAR) COMMUNICATION NETWORKS", filed September 2, 2008, and assigned to its applicant and expressly incorporated herein by reference ; and 61/122997 entitled "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS (OR CELLULAR) COMMUNICATION NETWORKS" filed December 16, 2008, and assigned to its applicant, and expressly incorporated herein by reference; and 61/151457, entitled "SYSTEM AND METHOD FOR PROVIDING GENERAL BIDIRECTIONAL IN-BAND MODEM FUNCTIONALITY" filed February 10, 2009, and assigned to its applicant, and expressly incorporated herein by reference; and 61/166904, entitled "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS (OR CELLULAR) COMMUNICATION NETWORKS", filed April 6, 2009, and assigned to its applicant and expressly incorporated herein by reference.

Related Applications

Pending related US patent applications include:

"SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS", which has the case number in the file of the attorney No. 081226U1, filed simultaneously with this application, assigned to the applicant of this application, and expressly incorporated herein by reference; "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS", which has the case number in the file of the attorney No. 081226U2, filed simultaneously with this application, assigned to the applicant of this application, and expressly incorporated into this document by reference; "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS", which has the case number in the file of the attorney No. 081226U3, filed simultaneously with this application, assigned to the applicant of this application, and expressly incorporated herein by reference. "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS", which has the case number in the file of the attorney No. 081226U5, filed simultaneously with this application, assigned to the applicant of this application, and expressly incorporated herein by reference. "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS", which has the case number in the file of the attorney No. 081226U6, filed simultaneously with this application, assigned to the applicant of this application, and expressly incorporated herein by reference.

State of the art

FIELD OF THE INVENTION

The present disclosure generally relates to data transmission over a voice channel. More specifically, the disclosure relates to the transmission of non-speech information through a speech codec (in-band) in a communication network.

Description of the Related Art

Voice transmission has been a major product in communication systems since the advent of fixed line telephones and wireless radios. Advances in the research and design of communications systems have led the industry to digital-based systems. One advantage of a digital communication system is the ability to reduce the required transmission bandwidth by implementing compression of the data to be transmitted. As a result, a lot of research and development has focused on compression techniques, especially in the field of speech coding. A conventional speech compression device is a “vocoder,” and is also interchangeably referred to as a “speech codec,” or “speech encoder.” A vocoder receives digitized speech samples and produces sets of data bits, known as “speech packets”. There are several standardized vocoding algorithms for supporting various digital communication systems that require voice communication, and in fact, today, voice support is the minimum and essential requirement in most communication systems. Third Generation Collaboration Project 2 (3GPP2) is an example of a standardization organization that specifies IS-95, CDMA2000 1xRTT (Single Carrier Radio Technology (1x)), CDMA2000 EV-DO (development of optimized data transfer) communications systems. The third-generation collaboration project is another example of a standardization organization that specifies GSM (global mobile communication system), UMTS (universal mobile communication system), HSDPA (high speed downlink packet access), HSUPA (high speed uplink packet access), HSPA + (development of high-speed packet access) and LTE (long-term development). VoIP (Voice over Internet Protocol) is an example protocol used in communication systems defined in 3GPP and 3GPP2, as well as in others. Examples of vocoders used in such communication systems and protocols include ITU-T G.729 (Communication Committee of the International Telecommunication Union), AMR (adaptive multi-speed speech codec) and EVRC (Version 3, 68, 70 of the advanced speech codec service with variable bit rate).

Sharing information is the main goal of today's communication systems in addition to the need for instant and ubiquitous connectivity. Users of today's communication systems transmit speech, video, text messages and other data in order to stay connected. Newly developed applications tend to be ahead of the development of networks and may require updating in communication systems modulation schemes and protocols. In some remote geographical areas, only voice services may be available due to the lack of infrastructure support for advanced voice services in the system. Alternatively, users may choose to include only voice services on their communication devices due to economic reasons. In some countries, communications networks are entrusted with supporting public services such as 911 Rescue Service (E911) or calling Rescue from Vehicle (eCall). In these examples of rescue services applications, fast data transfer is a priority, but not always realistic, especially when advanced data services are not available in the user terminal. Previous techniques provided solutions for transmitting data through a speech codec, but these solutions can only support data transmission at low speed due to coding inefficiency resulting from an attempt to encode non-speech signals with a vocoder.

The speech compression algorithms implemented by most vocoders use “synthesis analysis” techniques to model the human vocal tract with sets of parameters. Parameter sets typically include functions of digital filter coefficients, gain, and stored signals, known as a codebook, as a small example. The search for the parameters that most closely match the characteristics of the input speech signal is performed in the vocoder encoder. The parameters are then used in the vocoder decoder to synthesize an estimate of the input speech. The parameter sets available to the vocoder to encode the signals are tuned to the speech of the best model, characterized by periodic voice segments, as well as non-voice segments that have noise-like characteristics. Signals that do not contain periodic or noise-like characteristics are not efficiently encoded by the vocoder and can result in serious distortion in the decoded output signal in some cases. Examples of signals that do not exhibit speech characteristics include fast-changing, single-tone tones or multi-frequency DTMF tones. Most vocoders are unable to efficiently and efficiently encode such signals.

Data transmission through a speech codec for is commonly referred to as “in-band” data transmission, in which data is enclosed in one or more speech packets output from the speech codec. Several techniques use audio tones at predetermined frequencies within the speech frequency band to represent data. Using tones of predefined frequencies to transmit data through speech codecs, especially at high data rates, is unreliable due to the vocoders used in the systems. Vocoders are designed to simulate speech signals using a limited number of parameters. Limited parameters are insufficient to effectively simulate tones. The ability of vocoders to model tones is further impaired when trying to increase the data rate by rapidly changing tones. This affects the detection accuracy and results in the need to add complex circuits in order to minimize data errors, which in turn further reduces the overall data rate of the communication system. Therefore, there is a need to effectively and efficiently transmit data through a speech codec in a communication network.

Accordingly, it would be advantageous to provide an improved system for transmitting and receiving information through a speech codec in a communication system.

SUMMARY OF THE INVENTION

The embodiments disclosed herein satisfy the aforementioned stated needs by using an in-band modem to reliably transmit and receive non-speech information through a speech codec.

In one embodiment, a method for sending non-speech information through a speech codec comprises the steps of processing a plurality of input data symbols to create a plurality of first pulse signals, generating a plurality of first pulse signals to generate a plurality of generated first pulse signals, and coding a plurality of generated first pulse signals with using the speech codec.

In another embodiment, the apparatus comprises a processor configured to process a plurality of input data symbols to generate a plurality of first pulse signals, a shaping device configured to generate a plurality of first pulse signals to generate a plurality of generated first pulse signals, and a speech codec configured to encode a plurality of generated signals of the first pulse to create a speech packet.

In another embodiment, the device comprises means for processing a plurality of input data symbols for generating a plurality of signals of the first pulse, means for generating a plurality of signals of the first pulse for generating a plurality of generated signals of the first pulse, and a means for encoding the plurality of generated signals of the first pulse with a speech codec.

In another embodiment, a method for synchronizing non-speech frames through a speech codec comprises the steps of generating a predetermined sequence that is noise-like and resistant to speech frame errors, and sending a predetermined sequence through the speech codec.

In another embodiment, the device comprises a generator configured to generate a predetermined sequence that has noise-like characteristics and is robust against speech frame errors, and a speech codec configured to process a predetermined sequence to create a speech packet.

In another embodiment, the device comprises means for generating a predetermined sequence that has noise-like characteristics and is robust against speech frame errors, and means for sending a predetermined sequence through the speech codec.

In another embodiment, the method for obtaining non-speech data embedded in a vocoder package comprises the steps of receiving and decoding a vocoder package, filtering the decoded vocoder package until a synchronization signal is detected, timing offset is calculated based on the synchronization signal, and the non-speech data embedded in a decoded vocoder package based on timing offset.

In another embodiment, the device comprises a receiver configured to receive and decode the vocoder packet, a filter configured to filter the decoded vocoder packet until a synchronization signal is detected, a calculator configured to calculate a timing offset based on the synchronization signal, and an extraction device configured to extract non-speech data embedded in the decoded vocoder package based on the timing offset.

In another embodiment, the device comprises means for receiving and decoding a vocoder packet, filtering the decoded vocoder packet until a synchronization signal is detected, means for calculating a timing offset based on the synchronization signal, and means for extracting non-speech data embedded in the decoded vocoder packet on based bias timing.

In another embodiment, the method for controlling the transmissions of the source terminal from the destination terminal in the in-band communication system comprises the steps of transmitting the “Start” signal from the destination terminal, stop transmitting the “Start” signal upon detection of the first received signal, transmit the NACK signal from the destination terminal, and stop transmitting a NACK signal upon detection of a successfully received data message of the source terminal, transmitting the ACK signal from the destination terminal, and stop transmitting the ACK signal after EFINITIONS number of ACK signals have been transmitted.

In another embodiment, the device comprises a processor, a memory in electronic communication with the processor, and instructions stored in the memory, instructions are capable of performing the steps of: transmitting a “Start” signal from a destination terminal, stop transmitting a “Start” signal upon detection of the first the received signal, transmit the NACK signal from the destination terminal, stop transmitting the NACK signal upon detection of a successfully received data message of the source terminal, transmit the ACK signal from the destination terminal, and stop edachu ACK signal after a predetermined number of the ACK signals have been transmitted.

In another embodiment, the transmission control device of the source terminal from the destination terminal in the in-band communication system, comprises means for transmitting the Start signal from the destination terminal, means for stopping the transmission of the Start signal upon detection of the first received signal, means for transmitting the NACK signal from the destination terminal, means stop transmitting a NACK signal upon detection of a successfully received data message of the source terminal, means for transmitting the ACK signal from the destination terminal, and means increasing transmission of an ACK signal after a predetermined number of ACK signals has been transmitted.

In another embodiment, a method for controlling transmissions of a source terminal from a source terminal in an in-band communication system comprises the steps of detecting a request signal in a source terminal, transmitting a synchronization signal from a source terminal by detecting a request signal, transmitting a user data segment from the source terminal using the first scheme modulating and stop transmitting the user data segment upon detection of the first received signal.

In another embodiment, the device comprises a processor, memory in electronic communication with the processor, instructions stored in memory, instructions are capable of executing the steps of detecting a request signal in a source terminal, transmitting a synchronization signal from a source terminal upon detection of a request signal, transmitting a segment user data from the source terminal using the first modulation scheme and stop transmitting the user data segment upon detection of the first received signal but.

In another embodiment, a control device for transmitting a source terminal from a source terminal in an in-band communication system comprises means for detecting a request signal in a source terminal, means for transmitting a synchronization signal from a source terminal for detecting a request signal, means for transmitting a user data segment from a source terminal using a first modulation scheme and means for stopping the transmission of the user data segment by detecting the first received signal.

In another embodiment, the method for controlling bidirectional data transmissions from a destination terminal in an in-band communication system comprises the steps of transmitting a send signal from a destination terminal, stop sending a send signal upon detection of a first received signal, transmit a synchronization signal from a destination terminal, transmit a user data segment from the destination terminal using the first modulation scheme, and stop transmitting the user detection data segment a second received signal.

In another embodiment, the device comprises a processor, memory in electronic communication with the processor, instructions stored in memory, instructions are capable of performing the steps of transmitting a send signal from a destination terminal, stop sending a send signal upon detection of the first received signal, transmit a synchronization signal from the destination terminal, transmit the user data segment from the destination terminal using the first modulation scheme, and stop transmitting the user segment are treacherous data to detect the second received signal.

In another embodiment, the apparatus for controlling bidirectional data transmissions from a destination terminal in an in-band communication system comprises means for transmitting a send signal from a destination terminal, means for stopping transmission of a send signal upon detection of a first received signal, means for transmitting a synchronization signal from a terminal, means for transmitting a user data segment from a terminal assignment using the first modulation scheme, and means for stopping transmission of a user segment data on the detection of the second received signal.

In another embodiment, an in-band communication system from a vehicle accommodating a vehicle integrated system (IVS) to a public safety call answering point (PSAP) comprises one or more sensors located in the IVS for IVS sensor data supply, IVS transmitter located in IVS for transmitting IVS sensor data, PSAP receiver located in PSAP for receiving IVS sensor data, PSAP transmitter located in PSAP for transmitting PSAP command data, IVS receiver located in IVS for receiving PSAP command data, the IVS transmitter comprising an IVS message formatter for formatting IVS sensor data and creating an IVS message, an IVS processor for processing an IVS message and generating a plurality of generated IVS pulse signals, an IVS speech encoder for encoding the generated IVS pulse signals and generating the encoded IVS signal, an IVS synchronization generator for generating an IVS synchronization signal, and an IVS transmission controller for transmitting a sequence of IVS synchronization signals and IVS messages, the receiver The PSAP contains a PSAP detector for detecting the IVS synchronization signal and generating the PSAP synchronization flag, a PSAP demodulator for demodulating the IVS message and creating the received IVS message, the PSAP transmitter containing a PSAP message formatter to format the PSAP command data and creating the PSAP command message, a PSAP processor for processing the message PSAP commands and generating a plurality of generated PSAP pulse signals, a PSAP speech encoder for encoding the generated PSAP pulse signals and generating a coded PSAP signal, a sync generator ization PSAP for generating a PSAP synchronization signal, and a PSAP transmit controller for transmitting a sequence of PSAP synchronization signals and PSAP command messages; wherein the IVS receiver comprises an IVS detector for detecting a PSAP synchronization signal and generating an IVS synchronization flag, and an IVS demodulator for demodulating PSAP messages and generating a received PSAP message.

Brief Description of the Drawings

Aspects and related advantages of the embodiments described herein will become more apparent with reference to the following detailed description, together with the attached drawings, in which:

1 is a diagram of an embodiment of a source and destination terminal that use an in-band modem to transmit data through a speech codec in a wireless communication network.

2 is a diagram of an embodiment of a data modem used in an in-band communication system.

3A is a diagram of an embodiment of a clock signal generator.

3B is a diagram of another embodiment of a synchronization signal generator.

3C is a diagram of yet another embodiment of a synchronization signal generator.

4 is a diagram of an embodiment of a synchronization packet generator.

5 is a diagram of an embodiment of a sequence of synchronization packets.

6A is a diagram of an embodiment of a synchronization preamble sequence.

6B is a diagram of an embodiment of a sequence of a synchronization preamble with non-overlapping reference sequences.

FIG. 7A is a graph of a correlation output signal of a synchronization preamble, in which the preamble comprises non-overlapping reference sequences.

7B is a graph of a correlation output signal of a synchronization preamble, in which the preamble comprises overlapping reference sequences.

8A is a diagram of an embodiment of a synchronization message format.

8B is a diagram of another embodiment of a synchronization message format.

8C is a diagram of another embodiment of a synchronization message format.

9 is a diagram of an embodiment of a transmission data message format.

10 is a diagram of an embodiment of a composite synchronization and message format of transmission data.

11A is a graph of a power spectral density of a signal based on an in-band pulse versus frequency.

11B is a graph of a power spectral density of a signal based on an in-band tone versus frequency.

12 is a diagram of an embodiment of a data modulator using sparse pulses.

13 is a diagram of an embodiment of a representation of a sparse pulse data symbol.

14A is a diagram of an embodiment of an arrangement of a generated pulse within a modulation frame using a round-robin technique.

14B is a diagram of an embodiment of an arrangement of a generated pulse within a modulation frame for a typical example of the prior art.

15A is a diagram of an embodiment of a synchronization signal detector and a receiver controller.

15B is a diagram of another embodiment of a synchronization signal detector and a receiver controller.

16 is a diagram of an embodiment of a synchronization packet detector.

17A is a diagram of an embodiment of a synchronization preamble detector.

17B is a diagram of another embodiment of a synchronization preamble detector.

FIG. 18A is a diagram of an embodiment of a synchronization detector controller.

FIG. 18B is a diagram of another embodiment of a synchronization detector controller.

FIG. 19 is a diagram of an embodiment of a reception timing controller.

20 is a diagram of an embodiment of a reception data modem used in an in-band communication system.

21 is a diagram of an embodiment of an emergency call system integrated in a vehicle.

FIG. 22 is a diagram of an embodiment of an interaction of a data request sequence transmitted on a downlink in a destination communication terminal and a data response sequence transmitted on an uplink in a source communication terminal using interaction initiated by the destination terminal.

23A is a diagram of an embodiment of an interaction of a data request sequence transmitted on a downlink in a destination communication terminal and a data response sequence transmitted on an uplink in a source communication terminal using an interaction initiated by the source terminal.

23A is a diagram of another embodiment of an interaction of a data request sequence transmitted on a downlink in a destination communication terminal and a data response sequence transmitted on an uplink in a source communication terminal using interaction initiated by the source terminal.

24A is a diagram of an embodiment of an interaction of a bidirectional data request sequence and a data response sequence transmitted both in a downlink and an uplink.

24B is a diagram of another embodiment of an interaction of a bidirectional data request sequence and a data response sequence transmitted both in a downlink and an uplink.

25 is a diagram of an embodiment of a user data packet format, the user data length being less than the transmission packet size.

FIG. 26 is a diagram of an embodiment of a user data packet format, the user data length being larger than the transmission packet size.

27A is a diagram of an embodiment of an interaction of a transmission data request sequence and a transmission data response sequence, the user data length being greater than the transmission packet size.

27B is a diagram of another embodiment of an interaction of a transmission data request sequence and a transmission data response sequence, the user data length being greater than the transmission packet size.

27C is a diagram of yet another embodiment of an interaction of a transmission data request sequence and a transmission data response sequence, wherein the user data length is larger than the transmission packet size.

27D is a diagram of yet another embodiment of an interaction of a transmission data request sequence and a transmission data response sequence, the user data length being greater than the transmission packet size.

DETAILED DESCRIPTION

FIG. 1 shows an embodiment of an in-band data system that can be implemented within the wireless source terminal 100. The source terminal 100 communicates with the destination terminal 600 via communication channels 501 and 502, network 500, and communication channel 503. Examples of suitable radio communication systems include cellular telephony systems operating in accordance with the standards of the Global System for Mobile Communications (GSM), Universal Mobile Communications System of the Third Generation Collaboration Project (3GPP UMTS), Code Division Multiple Access 2 Third Generation Collaboration Project (3GPP2 CDMA), synchronous code division multiple access and time division multiple access (TD-SCDMA), and global microwave access communication network compatibility (WiMAX). One skilled in the art will understand that the techniques described herein can equally be applied to an in-band data system that does not involve a wireless channel. The communications network 500 includes any combination of routing and / or switching equipment, a communications link, and other infrastructure suitable for establishing a communications link between the source terminal 100 and the destination terminal 600. For example, communication channel 503 may be a non-wireless communication. The source terminal 100 typically functions as a voice communication device.

TRANSMITTER

The baseband transmission path 200 typically directs user speech through a vocoder, but is also capable of sending non-speech data through a vocoder in response to a request originating from a source terminal or communication network. The direction of non-speech data through the vocoder is advantageous, since it eliminates the need for the source terminal to request and transmit data over a separate communication channel. Non-speech data is formatted into messages. Message data, still in digital form, is converted into a noise-like signal containing the generated pulse. Information about these messages is embedded in the pulse position of the noise-like signal. A noise-like signal is encoded by a vocoder. The vocoder is not configured differently depending on whether the input signal is user voice or non-speech data, so it is advantageous to convert the message data into a signal that can be effectively encoded by the set of transmission parameters assigned to the vocoder. The encoded noise-like signal is transmitted in-band over a communication line. Since the transmitted information is embedded in the pulse positions of the noise-like signal, reliable detection depends on the restoration of timing of the pulse, relative to the frame boundaries of the speech codec. To help the receiver detect in-band transmission, a predetermined synchronization signal is generated and encoded by the vocoder before transmitting the message data. The sequence of the synchronization protocol, control, and messages is transmitted to ensure reliable detection and demodulation of non-speech data at the receiver.

As for the baseband transmission path 200, the input audio signal S210 is input into the microphone and the input audio signal processor 215 and transmitted through the multiplexer 220 to the vocoder encoder 270 in which compressed voice packets are generated. A suitable input audio signal processor typically includes a circuit for converting the input signal into a digital signal and a signal equalizer to generate a digital signal, such as a low-pass filter. Examples of suitable vocoders include those described by the following reference standards: GSM-FR, GSM-HR, GSM-EFR, EVRC, EVRC-B, SMV, QCELP13K, IS-54, AMR, G.723.1, G.728, G.729 , G.729.1, G.729a, G.718, G.722.1, AMR-WB, EVRC-WB, VMR-WB. Vocoder encoder 270 provides voice packets to transmitter 295 and antenna 296, and voice packets are transmitted over communication channel 501.

A data transfer request may be initiated by the source terminal or via a communication system. The data transfer request S215 terminates the voice path through the multiplexer 220 and implements the transmission data path. The input data S200 is pre-processed by the data message formatter 210 and output as Tx message S220 to the Tx Data Modem 230. The input data S200 may include user interface (UI) information, user position / location information, time stamps, equipment sensor information, or other suitable data. An example of a suitable data message formatter 210 includes a circuit to compute and apply cyclic redundancy check (CRC) bits to input data, provide retransmission buffer memory, implement error control coding such as hybrid automatic retry (HARQ), and interleave input data. The data Tx modem 230 converts the TX message S220 into Tx Data S230 data signal, which is routed through the multiplexer 220 to the encoder 270 vocoder. Once the data transfer is completed, the voice path can be re-implemented through the multiplexer 220.

FIG. 2 is a suitable exemplary block diagram of a data Tx modem 230 shown in FIG. Three signals can be time-multiplexed through multiplexer 259 to output signal Tx of data S230; synchronization output signal S245, muting output signal S240, and Tx modulator output signal S235. It should be understood that various orders and combinations of the synchronization output signal S245, muting output signal S240, and Tx modulator output signal S235 can be output to Tx data S230. For example, the synchronization output signal S245 may be sent before each data segment of the output signal S235 of the Tx modulator. Or, the synchronization output signal S245 may be sent once before mixing the Tx modulator output signal S235 and the muting output signal S240 sent between each data segment of the Tx modulator output signal S235.

The synchronization output signal S245 is a synchronization signal used to set timing in the receiving terminal. Synchronization signals are required to set the timing for transmitted in-band data, since data information is embedded in the pulse positions of the noise-like signal. Fig. 3A shows a suitable block diagram as an example of the Sync Generator 240 shown in Fig. 2. The three signals can be time-multiplexed through the multiplexer 247 to the synchronization output signal S245; a synchronization packet S241, an awakening output signal S236, and a synchronization preamble output signal S242. It should be understood that various orders and combinations of the synchronization packet S241, the wake-up output signal S236, and the synchronization preamble output signal S242 can be output to the synchronization output signal S245. For example, FIG. 3B shows a Sync Generator 240 comprising a wake-up output signal S236 and a synchronization preamble output signal S242, in which a wake-up output signal S236 may be sent before each synchronization preamble output signal S242. Alternatively, FIG. 3C shows a Sync Generator 240 comprising a synchronization packet S241 and a synchronization preamble output signal S242, in which a synchronization packet S241 may be sent before each synchronization preamble output signal S242.

Returning to FIG. 3A, the synchronization packet S241 is used to establish coarse timing at the receiver and contains at least one sine wave signal having a predetermined sampling frequency, sequence, and duration, and the synchronization packet 250 shown in FIG. 4 is generated. . Sinusoidal Frequency 1,251 represents binary data +1, and Frequency 2,225 represents binary data -1. Examples of suitable signals include constant frequency sinusoids in the voice band, such as 395 Hz, 540 Hz, and 512 Hz for one sinusoidal signal and 558 Hz, 1035 Hz, and 724 Hz for another sinusoidal signal. The sequence 253 synchronization packets determines which frequency signal is multiplexed through the multiplexer 254. The information sequence modulated into the synchronization packet should be a sequence with good autocorrelation properties. An example of a suitable Sequence 253 of a synchronization packet is the Barker code of length 7 shown in FIG. 5. For each '+' symbol, the Sine Wave of Frequency 1 is output to the synchronization packet S241, and for each '-' symbol, a Sine Wave of Frequency 2 is output.

Returning to FIG. 3A, the synchronization preamble output signal S242 is used to set the final (sample-based) timing in the receiver and contains a predetermined data pattern known in the receiver. A suitable example of the Synchronization Preamble Output Sequence S242 is the Synchronization Preamble Sequence 241 shown in FIG. 6A. The composite preamble sequence 245 is generated by linking several periods of the pseudo-random noise (PN) sequence 242 with the overlapping and added result of the PN 242 sequence and an inverted version of the PN sequence 244. The characters '+' in the composite sequence 245 of the preamble represent binary data +1, and the characters '-' represent binary data -1. Another suitable example inserts samples evaluated as zero between pieces of data of a PN sequence. This provides a time duration between the data bits in order to take into account the “blurring” effect caused by the characteristics of the channel bandpass filter, which tends to propagate the energy of the data bit over several bit time intervals.

The previously described generation of a synchronization preamble using associated periods of a PN sequence with overlapping segments of inverted versions of a PN sequence provides advantages in reducing transmission time, improved correlation properties, and improved detection characteristics. Advantages result in a preamble that is robust against speech frame errors.

By overlapping PN segments, the resulting composite synchronization preamble contains fewer bits in the sequence than the non-overlapping version, thereby reducing the total time required to transmit the composite preamble sequence 245.

To illustrate the improvement in the correlation properties of the overlapped synchronization preamble, FIGS. 7A and FIG. 7B show a comparison between the correlation of the PN sequence 242 with the non-overlapped composite preamble sequence 245b shown in FIG. 6B and the correlation of the PN sequence 242 with the overlapped synchronization preamble sequence 245 shown in Figa. 7A shows the main correlation peaks, both positive and negative, as well as minor correlation peaks located between the main peaks for the non-overlapping composite synchronization preamble sequence 245b. The negative peak 1010 is a consequence of the correlation of the PN sequence 242 with the first inverted segment of the uncoated composite preamble sequence 245b. The positive correlation peaks 1011, 1012, 1013 result from the correlation of the PN sequence 242 with the three connected segments of the PN sequence 242, which make up the middle section of the uncoated composite preamble sequence 245b. Negative peaks 1014 result from the correlation of the PN sequence 242 with the second inverted segment of the uncapped composite preamble sequence 245b. 7A, a slight correlation peak 1015 corresponding to an offset of 3 samples from the first positive correlation peak 1011 shows a value of approximately 5 (1/3 of the magnitude of the main peaks). Fig. 7B shows several major correlation peaks, both positive and negative, as well as minor correlation peaks between the main peaks for the overlapped composite synchronization preamble sequence 245. 7B, a slight correlation peak 1016, corresponding to an offset of 3 PN samples from the first positive correlation peak 1011, shows a value of approximately 3 (1/5 of the magnitude of the main peaks). The smaller value of the minor correlation peak 1016 for the overlapped preamble shown in FIG. 7B results in less false detection of major preamble correlation peaks compared to uncovered minor peaks 1015, an example shown in FIG. 7A.

As shown in FIG. 7B, five main peaks are generated when the PN sequence 242 is correlated with the sync preamble composite sequence 245. The pattern shown (1 negative peak, 3 positive peaks, and 1 negative peak) allows you to determine the timing of the frame based on any 3 detected peaks and the corresponding time durations between the peaks. The combination of 3 detected peaks with the corresponding time duration is always unique. A similar description of the correlation peak pattern is shown in Table 1, where the correlation peaks are indicated by '-' for the negative peak and '+' for the positive peak. The technique of using a unique correlation peak pattern is beneficial for in-band systems, since a unique pattern compensates for possible loss of speech frame, for example, due to poor channel conditions. Loss of speech frame can also lead to loss of a correlation peak. With a unique pattern of correlation peaks separated by predetermined time durations, the receiver can reliably detect a synchronization preamble even with lost speech frames, which result in lost correlation peaks. A few examples are shown in Table 2 for combinations of 3 detected peaks in the pattern (2 peaks lost in each example). Each entry in Table 2 represents a unique pattern of peaks and time durations between peaks. Example 1 in Table 2 shows the detected peaks 3, 4, and 5 (peaks 1 and 2 were lost), resulting in the pattern '+ + -' with one predetermined duration between each peak. Examples 2 and 3 in Table 2 also show the '+ + -' pattern, however the durations differ. Example 2 has two predefined durations between detected peaks 2 and 4, while Example 3 has two predetermined durations between detected peaks 3 and 5. Thus, Examples 1, 2 and 3 each represent a unique pattern from which there can be received frame timing. You need to understand that the detected peaks may go beyond the frame, but at the same time, unique patterns and predefined durations are still applicable.

Table 1 Correlation Peak Number one 2 3 four 5 Correlation Peak Polarity - + + + -

table 2 Correlation Peak Number one 2 3 four 5 Detected correlation peaks Example 1 + + - Example 2 + + - Example 3 + + - Example 4 + + + Example 5 - + - Example 6 - + - Example 7 - + + Example 8 - + - Example 9 - + + Example 10 - + +

One skilled in the art will understand that a different preamble sequence may be used, resulting in different correlation peak patterns, as shown in FIG. 7B and Table 1. One of ordinary skill in the art will also appreciate that multiple correlation peak patterns can be used to identify different modes of operation or transmit information bits. An example of an additional correlation peak pattern is shown in Table 3. The correlation peak pattern shown in Table 3 supports a unique pattern from which frame timing can be obtained, as described previously. The presence of multiple correlation peak patterns is advantageous in order to identify various transmitter configurations at the receiver, such as message formats or modulation schemes.

Table 3 Correlation Peak Number one 2 3 four 5 Correlation Peak Polarity + - - - +

Referring again to FIG. 3A, the wake-up output signal S236 is used to initiate wake-up of the vocoder encoder 270 so that from a sleep state, a low bit rate state, or a discontinuous transmission state. The wake-up output S236 can also be used to prevent the vocoder encoder 270 from entering a sleep state, low bit rate, or intermittent transmission. Awakening output signal S236 is generated by Awakening Generator 256. Wake-up signals are advantageous when transmitting in-band data through vocoders that implement sleep, discontinuous transmission (DTX) functions, or operate at a lower transmission rate during idle voice segments to minimize trigger delay that can occur when switching from a voice idle state to a state active voice. Wake-up signals may also be used to identify a transmission mode characteristic; for example, the type of modulation scheme used. A first example of a suitable wake-up output signal S236 is a single sinusoidal constant frequency signal in a speech frequency band, such as 395 Hz. In this first example, the Awakening signal prevents the vocoder encoder 270 from entering sleep, DTX, or a low bit rate state. In this first example, the receiver ignores the transmitted wake-up output signal S236. A second example of a suitable wake-up output signal S236 is a signal containing a plurality of sinusoidal signals with each signal identifying a particular data modulation scheme, for example, 500 Hz for modulation scheme 1 and 800 Hz for modulation scheme 2. In this second example, the wake-up output prevents the vocoder encoder 270 from entering a sleep, DTX, or low bit rate state. In this second example, the receiver uses the transmitted wake-up output signal S236 to identify the data modulation scheme.

An example of a composite sync output signal S245 is one that contains a multiplexed sync packet S241 and a sync preamble output signal S242, as shown in FIG. 8A. Tsb 701 and Tsp 702 represent the time duration when each signal is transmitted. An example of a suitable range for Tsb is 120-140 milliseconds, and Tsp is 40-200 milliseconds. Another example of a composite synchronization output signal S245 is one that comprises a multiplexed wake-up output signal S236 and a synchronization preamble output signal S242, as shown in FIG. 8B. Twu 711 and Tsp 702 represent the time duration when each signal is transmitted. An example of a suitable range for Twu is 10-60 milliseconds, and Tsp is 40-200 milliseconds. Another example of a composite synchronization output signal S245 is one that comprises a multiplexed wake-up output signal S236, a synchronization packet S241, and a synchronization preamble output signal S242, as shown in FIG. 8C. Twu 711, Tsp1 721, Tsb 701, Tsp2 722 represent the time duration when each signal is transmitted. An example of a suitable range for Twu is 20-80 milliseconds, Tspl is 40-200 milliseconds, Tsb is 120-140 milliseconds, and Tsp2 is 40-200 milliseconds.

Returning to FIG. 2, a suitable example of the output signal S235 of the Tx modulator is the signal generated by the Modulator 235 using positional pulse modulation (PPM) with special forms of modulation pulse. This modulation technique results in low distortion when coding and decoding by various types of vocoders. Additionally, this technique results in good autocorrelation properties and can be easily detected by a receiver matching the waveform. In addition, the generated impulse does not have a tonal structure; instead, the signals appear noise-like in the frequency spectrum region and also retain an audible noise-like characteristic. An example of a power spectral density of a signal based on generated pulses is shown in FIG. 11A. As can be seen in FIG. 11A, the power spectral density shows a noise-like characteristic over the in-band frequency range (constant energy over the frequency range). On the contrary, an example of a power spectral density of a signal with a tonal structure is shown in FIG. 11B, in which data is represented by tones at frequencies of approximately 400 Hz, 600 Hz, and 1000 Hz. As can be seen in FIG. 11B, the power spectral density depicts “bursts” of substantial energy over the in-band frequency range in the tone frequencies and its harmonics.

12 is an exemplary block diagram of a Modulator 235 shown in FIG. 2. The sparse pulse generator 238 produces a pulse corresponding to the input TX message S220 using positional pulse modulation and then the Pulse generator 239 generates a pulse to create a signal for better coding quality in the vocoder encoder. A suitable example of a sparse Impulse is shown in FIG. 13. The time axis is divided into modulation frames of duration T _MF . Within each such modulation frame, the number of times t ₀ , t ₁ , ..., t _m-1 is determined relative to the border of the modulation frame, which identifies the potential positions of the main pulse p (t) . For example, Impulse 237 at position t _{3 is} denoted as p (tt ₃ ) . The Tx information bits of the S220 message input to the Modulator 235 are mapped to symbols with a corresponding translation to the pulse positions according to the mapping table. A pulse can also be formed with a polarity conversion, ± p (t) . The symbols can therefore be represented by one of the distinct signals at 2m within the modulation frame, where m represents the number of times defined for the modulation frame and the multiplication factor, 2, represents the positive and negative polarity.

An example of a suitable display of the pulse position is shown in Table 4. In this example, the modulator displays a 4-bit symbol for each modulation frame. Each symbol is represented in terms of the position k of the pulse shape p (nk) and the sign of the pulse. In this example, T _MF is 4 milliseconds, resulting in 32 possible positions for a sampling frequency of 8 KHz. The pulses are separated by 4 points in time, which results in the assignment of 16 different positions of the pulse and combinations of polarity. In this example, the effective data rate is 4 bits per character in a period of 4 milliseconds or 1000 bits / sec.

Table 4 Symbol Pulse decimal binary 0 0000 p (n-0) one 0001 p (n-4) 2 0010 p (n-8) 3 0011 p (n-12) four 0100 p (n-16) 5 0101 p (n-20) 6 0110 p (n-24) 7 0111 p (n-28) 8 1000 -p (n-28) 9 1001 -p (n-24) 10 1010 -p (n-20) eleven 1011 -p (n-16) 12 1100 -p (n-12) 13 1101 -p (n-8) fourteen 1110 -p (n-4) fifteen 1111 -p (n-0)

Another example of a suitable display of the pulse position is shown in Table 5. In this example, the modulator displays a 3-bit symbol for each modulation frame. Each symbol is represented in terms of the position k of the pulse shape p (nk) and the sign of the pulse. In this example, T _MF is 2 milliseconds, resulting in 16 possible positions for a sampling frequency of 8 KHz. The pulses are separated by 4 points in time, which leads to the appointment of 8 different positions of the pulse and combinations of polarity. In this example, the effective data rate is 3 bits per character in a period of 2 milliseconds or 1500 bits / sec.

Table 5 Symbol Pulse decimal binary 0 000 p (n) one 001 p (n-4) 2 010 p (n-8) 3 011 p (n-12) four one hundred -p (n-12) 5 101 -p (n-8) 6 110 -p (n-4) 7 111 -p (n)

To increase reliability in poor channel conditions, the Modulator 235 can increase the duration of the modulation frame T _MF , while maintaining a constant number of times t ₀ , t ₁ , ..., t _m-1 . This technique serves to place a longer time duration between pulses, which results in more reliable detection. An example of a suitable pulse position display includes T _MF 4 milliseconds, resulting in 32 possible positions for a sampling frequency of 8 KHz. As in the previous example, if the pulses are separated by 4 points in time, the display results in the assignment of 16 different pulse positions and polarity combinations. However, in this example, the separation between times is increased by a factor of 2 from the previous example, resulting in 8 different pulse positions and polarity combinations. In a suitable example, Modulator 235 may switch between different displays of the position of the pulse or the duration of the modulation frame depending on the feedback signal indicating channel conditions or transmission success. For example, Modulator 235 can start transmitting using a T _MF of 2 milliseconds, then switch to T _MF of 4 milliseconds if the channel conditions are determined to be bad.

To increase reliability with certain vocoders, Modulator 235 may change the initial time offset in the display of the pulse position. An example of a suitable display of the pulse position is shown in Table 6. In this example, the modulator displays a 3-bit symbol per modulation frame. Each symbol is represented in terms of the position k of the pulse shape p (nk) and the sign of the pulse. In this example, T _MF is 2 milliseconds, resulting in 16 possible positions for a sampling frequency of 8 KHz. The initial offset is set at 1 point in time, and the pulses are separated by 4 time points, which results in the assignment of 8 different pulse positions and polarity combinations, as shown in the table.

Table 6 Symbol Pulse decimal binary 0 000 p (n-1) one 001 p (n-5) 2 010 p (n-9) 3 011 p (n-13) four one hundred -p (n-13) 5 101 -p (n-9) 6 110 -p (n-5) 7 111 -p (n-1)

It should be understood that a decrease in the number of times of separation would lead to an increased number of bits per symbol and thus higher data rates. For example, if T _MF is 4 milliseconds, the resulting number of possible positions for a sampling frequency of 8 KHz is 32 with positive or negative polarity for each, resulting in 64 different signals if no separation is enabled. For a 64-position display, the number of supported bits per character is 6, and the resulting effective data rate is 1500 bits per second. It should also be understood that various combinations of T _MF and sampling rates can be used to achieve the desired effective bit rate.

An example of a suitable Pulse Shaper 239 is a transform with the characteristic “root from a raised cosine”:

where β is the smoothing factor, 1 / T _s is the maximum symbol rate, and t is the sampling time.

For the previous example with 32 possible pulse positions (time instants), the following transformation generates a pulse shape with the characteristic "root from the raised cosine", where the number of zeros to the first nonzero element of the pulse determines the exact position of the pulse within the frame.

You need to understand that the conversion can be shortened or lengthened for different modulation frame sizes.

14A is an example of placing a pulse within a modulation frame to generate a specific input in the modulation alphabet. 14A, the pulse is represented by 13 samples, shown as P0-P12, where each sample represents the nonzero elements r (n) shown in the previous example. Figv is an example of a typical embodiment in the prior art. 14B, the position of the pulse is shifted by 7 within the TMF (n) 1003 modulation frame, and the tail portion of the pulse extends into the next TMF modulation frame (n + 1) 1004 by 4 samples (P9-P12). Samples from the TMF (n) 1003 modulation frame propagating to the next TMF (n + 1) 1004 modulation frame, as shown in FIG. 14B would result in intersymbol interference if the pulse samples for the TMF frame (n + 1) are positioned in any of the first 4 samples of the TMF frame (n + 1), since the samples would overlap. Alternatively, in the “loopback” technique shown in FIG. 14A, tail samples that would extend to the next modulation frame, T _MF (n + 1) 1004, are placed at the beginning of the current modulation frame, T _MF (n) 1003. Samples (P9-P12) cycle back to the beginning of T _MF (n) in samples 0-3. Using a cyclic return technique to generate a modulation alphabet eliminates cases in which samples of the generated pulse extend into the next modulation frame. The loopback technique is advantageous because it results in reduced intersymbol interference that would occur if samples of the generated pulse in an existing frame extend into the next frame and overlap with samples of the generated pulse in the next frame. One skilled in the art will understand that a round-robin technique could be used for any pulse position in a modulation frame, resulting in samples extending to the next modulation frame. For example, a pulse whose position is offset by 8 within the modulation frame TMF (n) 1003 would be a cyclically returning sample (P8-P12).

Another example of a suitable Pulse Shaper 239 is an amplitude, shape conversion signal:

r (n) p (n-t)

An example of an amplitude conversion signal from 32 samples has the form:

Another example of a suitable Pulse Shaper 239 is a linear prediction synthesizing filter. The response of an exemplary recursive synthesis filter with LPC is determined by its impulse response

$$h(n)=\delta (n)+{\displaystyle \sum _{i=\mathrm{one}}^{10}{a}_{i}h(n-i)}$$

And with the coefficients: a (i) = {- 6312, 5677, -2377, 1234, -2418, 3519, -2839, 1927, -629, 96} / 4096, i = 1 ..., 10. Linear prediction filters well known in the art. The residual signal r (n) is first created by the input symbols according to the above pulse mapping tables. The actual shape of the modulation pulse then follows from filtering the modulated signal r (n) with h (n) .

One skilled in the art will understand that the techniques described herein can be equally applied to various waveforms and transformations. The waveform lengths and modulation schemes applicable to these waveforms may also vary. In addition, waveforms can use completely uncorrelated (or orthogonal) waveforms to represent different symbols. In addition to the polarity of the generated pulse, the amplitude of the generated pulse can also be used to carry information.

Referring again to FIG. 2, the muting output signal S240 is a signal used to separate the Tx message transmissions and is generated by the muting Generator 255. An example of a suitable composite Data signal Tx S230 comprising a multiplexed output signal S235 of a Tx modulator and a muting output signal S240 is shown in FIG. 9. Tmu1 731, Td1 732, Tmu2 733, Td2 734, Tmu3 735, Td3 736, and Tmu4 737 represent the time duration when each signal is transmitted. An example of a suitable range for Tmu1, Tmu2, Tmu3, and Tmu4 is 10-60 milliseconds and Td1, Td2, and Td3 are 300-320 milliseconds for normal operation and 600-640 milliseconds for reliable operation. Examples of a suitable muting generator sequence may be signals with a completely zero sequence or a sinusoidal frequency signal. Another suitable example of a signal used to separate transmissions of a Tx message is shown in FIG. 10. In this example, the wake-up output signal S236 and the synchronization preamble output signal S242 precede each transmission of the Tx modulator output signal S235. One skilled in the art will recognize that various combinations of the output signal S242 of the synchronization preamble, the output muting signal S240, and the output signal S235 of the Tx modulator can be equally applied. For example, the output signal S235 of the Tx modulator in FIG. 10 may precede and follow the muting output signal S240.

Receiver

With reference to FIG. 1, a baseband receive path 400 typically directs decoded voice packets from a vocoder to an audio processor, but is also capable of directing decoded packets through a data demodulator. Since non-speech data has been converted to a noise-like signal and encoded by a vocoder in the transmitter, the receiver vocoder is able to efficiently decrypt the data with minimal distortion. Decoded packets are continuously monitored for an in-band synchronization signal. If a synchronization signal is found, frame timing is restored, and decoded packet data is sent to the data demodulator. Decoded packet data is demodulated into messages. Messages are deformed and displayed. The protocol sequence, including synchronization, control, and messages, ensures reliable detection and demodulation of non-speech data.

Voice packets are received via communication channel 502 at receiver 495 and input to a vocoder decoder 390 where a decrypted voice is generated, then sent through a demultiplexer 320 to an audio processor and speaker 315 generating an audio output signal S310.

As soon as the synchronization signal is detected in the Output signal S370 of the Vocoder Decoder by the Synchronization Detector 350, the Rx demultiplexer control signal S360 switches to the Rx data path of the Rx demultiplexer 320. The vocoder packets are decoded by the vocoder decoder 390 and sent by the Rx demultiplexer 320 to Rx timing 380, then to the Rx data modem 330. The Rx data is demodulated by the Rx data modem 330 and sent to the data message formatter 301, where the output of the S300 is made available to the user or interaction equipment.

An example of a suitable data message formatter 301 includes a circuit for de-interleaving Rx data of an S320 message, implementing error control decoding such as Hybrid Automatic Repeat Request (HARQ), and computing and checking cyclic redundancy check (CRC) bits. Suitable S300 output may include user interface (UI) information, user position / location information, time stamps, equipment sensor information, or other suitable data.

FIG. 15A is a suitable exemplary block diagram of a Receiver and Synchronization Detector Controller 350 shown in FIG. The output signal S370 of the Vocoder Decoder is input to a Sync packet detector 360 and a Sync preamble Sensor 351. The sync packet detector 360 detects the transmitted sync packet signal in the Vocoder Decoder Output S370 and generates a packet sync index S351. The synchronization preamble detector 351 detects the transmitted synchronization preamble output signal in the output signal S370 of the vocoder decoder, and generates a preamble synchronization index S353. Signals A packet synchronization index S351 and a Preamble synchronization index S353 are input to the Synchronization Detector Controller 370. The sync detector controller 370 generates control outputs S360 of the Rx demultiplexer, which directs the output signal S370 of the Vocoder decoder to the data path S326 or the audio path S325, the audio mute control S365, which turns the audio output S310 on or off, and the timing offset S350, which provides information about timing bits in Rx timing 380 to align Rx S326 data for demodulation.

Another example of a suitable synchronization detector 350 is shown in FIG. 15B. The output signal S370 of the Vocoder Decoder is input into memory 352 and Synchronization Preamble Detector 351. A memory 352 is used to store the latest samples of the Vocoder Decoder Output S370, which include the received wake-up output. A suitable example of memory 352 is First-In-First-Out (FIFO) or Random Access Memory (RAM). The Synchronization Preamble Detector 351 detects the transmitted synchronization preamble output signal in the Output signal S370 of the Vocoder Decoder, and outputs a signal of the synchronization flag S305. A signal modulation type S306 and a synchronization flag S305 are input to the Sync Detector Controller 370. The Sync Detector Controller 370 generates a Modulation Search signal S307, which is used to access the memory 352, find the received wake-up output signal based on the timing offset S350, and evaluate the wake-up signal output to determine the type of modulation used in the transmission. The resulting detected modulation type is output from the memory 352 as Modulation Type S306. The Sync Detector controller 370 also generates S360 Control output signals from the Rx demultiplexer that directs the S370 Output signal of the Vocoder Decoder to the data path or audio path, the S365 Audio Mute Controls that turn the S310 audio output on or off, and the Sync Bias S350, which provides timing information bits in Rx timing 380 to align Rx S326 data for demodulation.

An example of a suitable Packet Synchronization Detector 360 is shown in FIG. 16. The output signal S370 of the Vocoder Decoder is input to a power calculator 361. Examples of a suitable power calculator 361 include a function for squaring an input signal or an absolute value function calculated on an input signal. The output signal S370 of the Vocoder Decoder is also input into the mixer function 362, where it is multiplied by the common-mode and quadrature components of the reference Sine Wave 1 363 Frequency and the Sine Wave 2364 Frequency to generate signal components converted with decreasing frequency at a frequency of 0 Hz. The output of mixer 362 is low-pass filtered by LPF 365 to eliminate high frequency harmonics in the mixed output. An exemplary transfer function of a suitable LPF 365 takes the form:

where c = 0.0554, a ₁ = 2, a ₂ = 1, b ₁ = -1.9742, b ₂ = 0.9744. The magnitude of the common-mode and quadrature output signals of the LPF 365 is calculated by a value of 366 and summed in the adder 367. The output of the adder 367 is input into a matched Filter 368, which is consistent with the transmitted Sync packet sequence. Matching Filters are well known in the art. The output of the matched Filter 368 searches for the maximum peak in the Search 369 Maximum. Once the maximum is found in the Maximum Search 369, the index corresponding to the maximum time offset is output in the packet synchronization index signal S351.

An example of a suitable Synchronization Preamble Detector 351 is shown in FIG. 17A. The output signal S370 of the Vocoder Decoder is processed by a matched Filter 368, which is matched with the Sync Preamble Sequence. The output of the matched Filter 368 is then input into the Maximum Search 369, which searches for the maximum peak. Once the maximum is in the Maximum Search 369, an index corresponding to the maximum time offset is displayed in the Preamble synchronization index S353.

Another example of a suitable Synchronization Preamble Detector 351 is shown in FIG. 17B. The output signal S370 of the Vocoder Decoder is processed by the filter in step 452. A suitable example of the filter in step 452 is a sparse filter with coefficients based on the baseband filtering pulse response of the Sync Preamble Sequence. A sparse filter has a structure with a finite impulse response with some of the coefficients set to zero and results in a reduction in computational complexity based on fewer required factors due to zero coefficients. Sparse filters are well known in the art. At step 453, a search is made in the filter output for the maximum positive and negative correlation peaks that match the expected pattern based on the negative and positive duration of the correlation peak. For example, in step 453, 5 peaks should be found based on the Synchronization Preamble Sequence 245, 3 positive peaks corresponding to correlations with a pseudo-random noise (PN) sequence 243, and 2 negative peaks corresponding to correlations with an inverted version of PN sequence 244. In a suitable example, the detector synchronization must find at least 2 peaks to announce that the synchronization preamble is detected. At step 461, the number of peaks detected is considered, and if most peaks are detected, then the synchronization indicator flag is set to True at step 460, indicating that a synchronization preamble has been detected. A suitable example when most peaks are detected is 4 out of 5 peaks that correspond to the expected pattern. If most peaks are not detected, control proceeds to step 454, in which the time duration between the positive peaks found in step 453 is compared with the expected duration, PeakDistT1. PeakDistT1 is set as a function of the period of the PN sequence 242 since filtering the received preamble against the PN sequence 242 should lead to a time duration between the correlation peaks, which is equal to a multiple of the number of periods. If the time duration between the positive peaks is within the range of PeakDistT1, then the positive peak amplitudes are checked against the PeakAmpT1 threshold at step 455. The suitable range for PeakDistT1 is plus or minus 2 samples. PeakAmpT1 is a function of the amplitudes of the previous peaks found. In a suitable example, PeakAmpT1 is set so that the peaks found in step 453 do not differ in amplitude by more than a factor of 3, and the average peak amplitude does not exceed half the maximum peak amplitude observed to this point. If either checking the time duration of the positive peak in step 454 or checking the amplitude in step 455 failed, then the time duration of the negative peak is checked in step 456. If the time duration of the negative peak is within the range of PeakDistT2, then the amplitudes of the negative peaks are checked against the threshold PeakAmpT2 in step 457. A suitable range for PeakDistT2 is plus or minus 2 samples. PeakDistT2 is set as a function of the PN period of the sequence 242, and PeakAmpT2 is set as a function of the amplitudes of the previous peaks found. If either checking the time duration of the positive peaks in step 454 and checking the amplitude of the positive peaks in step 455, or checking the time duration of the negative peaks in step 456 and checking the amplitude of the negative peaks in step 457, then the synchronization indicator flag is set to True in step 460, indicating that a preamble synchronization has been detected. If either checking the time duration of the negative peaks at step 456 or checking the amplitude of the negative peaks at step 457 failed, then the synchronization indicator flag is set to False at step 458, indicating that no synchronization preamble has been detected. It should be understood that different order and combinations of steps will achieve the same result. For example, the detection of most peaks in step 461 can be done after checking the positive peaks in steps 454 and 455.

An example of a suitable Synchronization Detector Controller 370 is shown in FIG. 18a. Step 407 is an entry point in the controller that initializes the memory buffers and configures the initial state of the receiver. At 406, a synchronization search type is checked, indicating whether the synchronization signal is searched in the Rx data or Rx audio path. Step 372 is entered if a synchronization search is performed on the Rx audio path. Using the packet synchronization index S351, the maximum synchronization packet and index are searched for by the determined number N1 of processing frames in step 372. Step 373 determines whether the maximum synchronization packet and the index that were searched in step 372 pass by the criterion of successful search. An example of a suitable search decision criterion in step 373 has the form:

(s _{max max} ≥h _SB ) and (i _smax ≤ _sync -N _guard )

where s _{max max} is the maximum of synchronization packets found from N1 processing frames, Th _SB is the threshold for detecting synchronization packets, i _smax is the index of the maximum synchronization packets, N _sync is the number of processing frames that were searched, and N _guard is the waiting period in processing frames. If the synchronization packet is not found, control proceeds back to step 406, and the search is restarted. If a synchronization packet is found, control proceeds to step 374 where an S365 Audio Mute Control signal is generated to prevent the audio path from being output to the speaker. In step 375, using the Preamble synchronization index S353, the maximum synchronization preamble and index are searched for a certain number N2 of processing frames. Step 376 determines whether the maximum synchronization preamble and the index used to search in step 375 pass by the criterion of successful search. An example of a suitable search decision criterion in step 376 has the form:

(s ₁ · ( s _{max max /} P (i _smax )) ² ) + c _{2 ·} z ² _{max max} ) ≥h _PD

Wheres _{max max} is the maximum of synchronization packets found by N1 processing frames, c_one and c₂are scale factors, z_{max max} is the maximum of the output of the matched filter 368 in the Sync Preamble Detector 351,P (i _smax )is an maximum input power, for Search 369 Maximum in the Detector 360 synchronization packets at the maximum index of the synchronization packet,i _smax.

If the synchronization preamble is not found at step 376, control proceeds back to step 406, and the search is restarted. If the synchronization preamble is found, the Control signal S360 of the Rx Demultiplexer is generated in step 378 to switch to the Rx data path in the Demultiplexer 320. The control then proceeds to step 377, in which the timing offset signal S350 is calculated. An example of a suitable Timing Offset calculation is of the form:

Timing Offset = ((i _zmax -N _sync -1) • N _samp ) + (k _max • i _zmax )

where i _zmax is the index at the maximum of the output of the matched filter 368 in the Synchronization Preamble Detector 351 per frame, N _sync is the number of processing frames to be searched, N _samp is the number of samples in one frame, and k _max is the phase of the maximum output a matched filter signal 368 in the Sync Preamble Detector 351 per frame. The control then proceeds to step 418, in which the Rx 330 modem is turned on using the Rx Modem S354 Turn-on signal, then it finally goes back to step 406 and the search is restarted. Step 372a is entered if a synchronization search is performed on the data path Rx. Steps 372a, 373a, 375a, and 376a act in the same way as steps 372, 373, 375, and 376, respectively; the main difference is that the audio path is not muted and the Demultiplexer does not switch from Audio Rx to Rx data, because the Sync Search Type checked in step 406 is Rx Data.

Another example of a suitable Synchronization Detector Controller 370 is shown in FIG. 18B. Step 407 is an entry point in the controller that initializes the memory buffers and configures the initial state of the receiver. At step 406, the type of synchronization search is checked to determine whether the synchronization signal is searched in the Rx data or Rx audio path. Control then proceeds to step 411, in which the Preamble Detector 351 is turned on. Step 412 checks the synchronization flag signal S305, indicating that the synchronization preamble has been found, then confirms this by repeatedly checking the synchronization flag S305 for a total of N times. A suitable value for N is 1 (which means that only 1 preamble is detected without confirmation) for Destination Terminal 600 and 3 for Source Terminal 100. If the synchronization preamble is located, an audio mute control signal S365 is generated to prevent the audio path from being output to loudspeaker. The control signal S360 of the Rx Demultiplexer is then generated in step 378 to switch from the Rx audio path to the Rx data path in the Demultiplexer 320. The control then proceeds to step 377, in which the timing offset signal S350 is calculated. An example of a suitable Timing Offset calculation is of the form:

Timing Offset = PulsePosition + PeakDistance

PulsePosition is a time duration from a positive correlation peak to the first reference point in time, and can be a positive or negative value. PeakDistance is the time duration between a positive correlation peak and a negative correlation peak. An example of a suitable first reference point in time may be a specific sample position relative to the currently received speech frame. Another example of a suitable Timing Offset calculation is of the form:

Timing Offset = PulsePosition

PulsePosition is a time duration from a negative correlation peak to a second reference point in time, and can be a positive or negative value. An example of a suitable second reference time may be a specific sample position relative to the currently received speech frame. Control then proceeds to step 414, in which the Modulation Type is determined by the Modulation Search signal S307 by searching the memory 352 at a predetermined position in which the received wake-up output signal should be stored. Control then proceeds to step 418, in which the Rx Modem 330 is turned on using the Rx Modem S354 Turn On signal. The demodulation scheme used in Turning on the S354 of the Rx Modem is determined in step 418 by an input signal of Type S306 Modulation. Control finally moves back to step 406, and the search restarts. Step 411a is entered if a synchronization search is performed on the data path Rx. Steps 411a, and 412a act in the same way as steps 411, and 412, respectively; the main difference is that the audio path is not muted and the Demultiplexer does not switch from Audio Rx to Rx data, because the Sync Search Type checked in step 406 is Rx Data. It must be understood that different order and combinations of steps will achieve the same result. For example, the steps of the Audio Muting Path 374 and the Path Switching Step 378 may be canceled if there is no effect of full synchronization detection.

FIG. 19 is a suitable exemplary block diagram of the timing of 380 Rx shown in FIG. Rx timing 380 is used to align the boundary of the modulation frame in the output from the vocoder decoder 390 so that demodulation can occur in the Rx data modem 330. The S326 Rx Signal data is entered into Buffer 381, where several samples are stored. Suitable examples of Buffers 381 include First-In-First-Out (FIFO) memory or random access memory (RAM). Samples from Buffer 381 are input into Variable Delay 382, the delay being applied to align the boundary of the modulation frame corresponding to the timing offset control signal S350. The suitable delay applied in Variable Delay 382 can be any number of samples from zero to a frame size of 1. The delayed signal is output as adjusted S330 Rx Data.

FIG. 20 is a suitable exemplary block diagram of an Rx 330 data modem shown in FIG. The two signals are time demultiplexed from the input signal S330 of the adjusted Rx Data via the Demultiplexer 331 of the Rx Data Modem; a muting demultiplexer S332, and an Rx data demultiplexer S333. The muting demultiplexer S332 is a separation or muting period that may exist between successfully received messages and is separated from the adjusted S330 Rx Data signal if signal separation or muting was applied in the transmitter. The Rx Demultiplexer Data S333 is the received modulated message input signal in the Demodulator 335. The Demodulator 335 demodulates the received message information bits from the adjusted S330 Rx Data. The Rx data modem 330 uses the demodulation frame boundary determined by timing Rx 380 and the demodulation type indicator determined by the Synchronization Detector Controller 370 to determine the position of the data signal pulse and calculate the output data symbol based on the position of the data signal pulse. An example of a suitable demodulator is a matched filter correlator consistent with all available cyclic shifts of the modulation pulse shape applied by the transmission data modulator. Another example of a suitable demodulator is a matched filter correlator, matched to the pulse version applied by the transmission data modulator filtered by the base frequency band, the band-pass filter representing channel transmission characteristics.

SYSTEM

FIG. 21 is an exemplary use of the system and methods disclosed herein. The diagram is a typical example of an emergency call system in a vehicle (eCall). Vehicle accident 950 is shown as an accident between two vehicles. Other suitable examples of vehicle accident 950 include an accident in multiple vehicles, an accident in one vehicle, a flat tire in one vehicle, an engine failure in one vehicle, or other situations where the vehicle is faulty or the user needs help. Vehicle system 951 (IVS) is located in one or more vehicles involved in a vehicle accident 950, or may be located directly on a user. The vehicle system 951 may comprise a source terminal 100 described herein. The vehicle system 951 communicates over a wireless channel, which may comprise an uplink channel 501 and a downlink channel 502. A request for data transmission can be accepted by the System in a vehicle through a communication channel, or it can be automatically or manually generated in the System in a vehicle. Wireless tower 955 receives transmission from System 951 in a vehicle and communicates with a wired network comprising an uplink wired channel 962 and a downlink wired channel 961. A suitable example of a wireless tower 955 is a cellular telephone tower comprising antennas, transceivers, and backhaul equipment well known in the art in order to communicate with wireless uplink 501 and downlink 502. The wired network communicates with the Public Safety Call Response Point (PSAP) 960, in which the emergency information transmitted by System 951 in the vehicle can be received and data can be controlled and transmitted to it. The public security call answering point 960 may comprise a destination terminal 600 described herein. Transmission between the System in the vehicle 951 and the public safety call answering point 960 is performed using the interaction scheme described in the following sections.

Fig is an exemplary diagram of the interaction of the sequences of synchronization and data transmission between the Source Terminal 100 and the Terminal 600 destination. In this example, the uplink transmission sequence 810 is initiated by the Destination Terminal 600. The downlink transmission sequence 800 is the transmission of synchronization and data messages from the destination terminal 600 to the source terminal 100, and the uplink transmission sequence 810 is the transmission of synchronization and data messages from the source terminal 100 to the destination terminal 600. The downlink sequence 800 is initiated at time t0 850 by the Destination terminal 600 with a synchronization sequence 801. Suitable examples of the synchronization sequence 801 are described in FIG. 8A, FIG. 8B, and FIG. 8C. After the synchronization sequence 801, the Destination terminal 600 transmits a “Start” message 802 to issue a command to the Source Terminal 100 to start transmitting its uplink transmission sequence 810. Destination terminal 600 continues to transmit synchronization 801 and the Start message 802 alternately and waits for a response from Source Terminal 100. At t1 851, Source Terminal 100, which received the Start message 802 from destination terminal 600, starts transmitting its synchronization sequence 811. Suitable examples of the synchronization sequence 811 are described in FIG. 8A, FIG. 8B, and FIG. 8C. After synchronization sequence 811, the Source Terminal 100 transmits a minimum data set message (or "MSD") 812 to the Destination Terminal 600. A suitable example of data containing an MSD message 812 includes a sensor or user data formatted by a data message formatter 210. At time t2 852, the Destination terminal 600, having received the synchronization message 811 from the Source Terminal 100, starts transmitting a negative acknowledgment message (or "NACK" 803) to the Source Terminal 100. The destination terminal 600 continues to transmit synchronization 801 and the "NACK" message 803 alternately, while it does not successfully receive the MSD message 812 from the Source Terminal 100. A suitable example of successfully receiving the MSD message 812 includes a cyclic redundancy check check performed on the MSD message 812. During t3 853, the Destination Terminal 600, having successfully received the MSD message, begins to transmit alternately the synchronization 801, and a confirmation message (or “ACK”) 804. The source Terminal 100 may attempt to send the MSD message 812 repeatedly (813, 814) until it receives the ACK message 804. In a suitable example, if the Source Terminal 100 attempts to send an MSD message more than 8 times, and each attempt is a version with different redundancy, it switches to a more stable modulation scheme identified by the Awakening signal S236. A suitable example of a more robust modulation scheme includes increasing the length of the modulation frame T _MF while maintaining a constant number of time instants, as described previously. At time t4 854, the Source Terminal 100, having received the ACK message 804 from the Destination Terminal 600, stops transmitting the MSD message 814. In a suitable example, a retransmission is requested by the Destination Terminal 600 by sending “start” messages 802 again after a predetermined number of “ACK” messages 804 have been sent by the Destination Terminal 600.

Figa is another exemplary diagram of the interaction of sequences of synchronization and data transmission between the Source Terminal 100 and the Terminal 600 destination. In this case, the Uplink Transmit sequence 810 is triggered by the Source Terminal 100. The Uplink Transmit sequence 810 is triggered at time t0 850a by the Source Terminal 100 with voice data 815 by configuring the transmission path 200 of the baseband of the Source Terminal 100 to the Tx audio path S225. During tl 851a, the Source Terminal 100 configures the baseband transmission path 200 to the Tx data path S230 and starts transmitting its synchronization sequence 811, followed by an MSD message 812. At t2 852a, the Destination Terminal 600, which received the synchronization message 811 from the Source Terminal 100, starts to transmit the synchronization 801 and the NACK message 803 to the Source Terminal 100. The destination terminal 600 continues to transmit the 801 synchronization and the NACK message 803, while it does not successfully receive the MSD message from the Source Terminal 100. At time t3 853, the Destination Terminal 600, having successfully received the MSD message 813, starts transmitting synchronization 801 alternately, and the acknowledgment or message 804 is “ACK”. The source Terminal 100 may attempt to send the MSD message 812 repeatedly until it receives the ACK message 804, each attempt being a version with different redundancy. At t4 854, the Source Terminal 100, having received the ACK message 804 from the Destination Terminal 600, stops transmitting the MSD message 814.

FIG. 23B is another exemplary diagram of the interaction of synchronization sequences and data transmission between the Source Terminal 100 and the Destination Terminal 600. In this case, the Uplink Transmit sequence 810 is initiated by the Source Terminal 100. Instead of transmitting voice data on the uplink to initiate the transmission, the Source Terminal 100 alternately transmits the synchronization 811 and the “SEND” message 805 at t0 850b. At time t1 851b, the Destination Terminal 600, having received the “SEND” message 805 from the Source Terminal 100, alternately transmits the synchronization 801, and the “Start” message 802. At time t2 852b, the Source Terminal 100, having received the Start message 802 from the Destination Terminal 600, transmits a synchronization sequence 811 followed by the MSD message 812 to the Destination Terminal 600. During t3 853b, the Destination Terminal 600, which received the synchronization message 811 from the Source Terminal 100, transmits the synchronization 801 and the NACK message 803 to the Source Terminal 100. At the time t4 854b, the Destination Terminal 600, which successfully received the MSD message, transmits the 801 synchronization and message 804 "ACK". After receiving the ACK message 804 from the Destination Terminal 600, the Source Terminal 100 stops transmitting the MSD message.

Figa is an exemplary diagram of the interaction of sequences of synchronization and data transmission between the Source Terminal 100 and the Terminal 600 destination. In this case, data is requested and transmitted by both the Source Terminal 100 and the Destination Terminal 600 on the uplink and downlink, respectively, to support bidirectional data transmission. The uplink Transmission sequence 800 is initiated at time t0 850 by the Destination Terminal 600 using an alternating synchronization sequence 801 and a Start message 802. At time t1 851, the Source Terminal 100, having received the Start message 802 from the Destination Terminal 600, starts transmitting its synchronization sequence 811, with subsequent data 812. At t2 852, the Destination Terminal 600 transmits the synchronization 801 and the NACK message 803, until it successfully receives data 812 from the Source Terminal 100, to which then the Destination Terminal 600 alternately sends a synchronization sequence 801 and an ACK message 804. At time t4 854, the Source Terminal 100, having received the ACK message 804 from the Destination Terminal 600, stops transmitting data. During t5 855, the Destination Terminal 600 alternately transmits a synchronization sequence 801 and a “SEND” message 805 indicating a downlink data request. During t6 856, the Source Terminal 100, upon detection of a “SEND” message 805, responds alternately with the synchronization sequence 811, and a “Start” message 816. During t7 857, the Destination Terminal 600, after detecting a “Start” message 816, responds with a synchronization sequence 801, followed by 806. At t8 858, the Source Terminal 100 alternately transmits a synchronization sequence 811 and a “NACK” message 817 until it is successful will not receive data 806 from the Destination Terminal 600, to which, at time t9 859, the Source Terminal 100 alternately sends a synchronization sequence 811 and an ACK message 818. During t10 860, the Destination Terminal 600, having received the ACK message 818 from the Source Terminal 100, stops transmitting its data 806. One skilled in the art will understand that the interactions described herein are symmetrical and can be triggered by the Source Terminal 100. To a person skilled in the art It will also be appreciated by the technical field that each of the synchronization sequence, “start” messages, NACK messages, and ACK messages may be the same or different sequences between downlink and uplink going line.

Fig. 24B is another exemplary diagram of the interaction of synchronization and data transmission sequences between the Source Terminal 100 and the Destination Terminal 600, in which data is requested and transmitted by both the Source Terminal 100 and the Destination Terminal 600 on the uplink and downlink. The difference between the interactions of FIG. 24B and FIG. 24A is t3 853. In this example, the alternate synchronization 801 and the “SEND” message 805 are transmitted by the Destination Terminal 600 instead of the alternate synchronization and the “ACK” message. In this example, the “SEND” message 805 serves to indicate that the Destination Terminal 600 has successfully received data 812 of the Source Terminal 100, and that causes the data transmission to t4 854 to be stopped by the Source Terminal 100. The “SEND” message also indicates a request from the Terminal 600 Destination to send data on the downlink.

FIG. 25 is an example composition diagram of a transmission data packet by which the length of user data is less than the length of the transmission data packet. A user data segment 900 is collected into a transmission data packet 806 or 812 along with a previous length indicator 910 and a subsequent sequence of fill bits 911, which serves to fill the data to the end of the transmission data packet. A suitable example for a length indicator 910 is a 1-3 byte value indicating a length of a user data segment 900. A suitable example of a transmission data packet length of 806 or 812 may be 100-200 bytes. A suitable example of padding bits 911 includes a binary “0” value. One skilled in the art will understand that the padding bits 911 may contain a binary value of “1” or may contain a binary value pattern of “1” and “0”.

FIG. 26 is an example composition diagram of a transmission data packet by which the length of user data is greater than the length of the transmission data packet. The user data 900 is divided into multiple segments such that the first segment plus a length indicator is equal to the length of the transmission data packet, and subsequent segments are equal to the length of the transmission data packet. If the user data is not an integer multiple of the length of the transmission data packet, then the last segment contains the padding. In the example of FIG. 26, user data is divided into two segments. The first user data segment 901 is collected in a transmission data packet 806 or 812 along with the previous length indicator 910. The second user data segment 902 is collected in a transmission data packet 806 or 812, and because the segment is less than the length of the transmission data packet, padding 911 is used to fill the data to the end of the transmission data packet.

27A is an example interaction diagram of a transmission data request sequence and a transmission data response sequence in which a user data length is greater than a transmission packet size. Initiated by the Start message, either on the downlink 800 or on the uplink 810, at time t20 870, the first transmission data packet 806 or 812 containing the length indicator 910 and the first user data segment 901 is transmitted by the responding terminal. During t21 871, since the responding terminal has not yet received the ACK message, it starts transmitting user data again in the second attempt 903. At t22 872, the responding terminal receiving the ACK message stops transmitting the first data packet 806 or 812. At time t23 873, the requesting terminal, after evaluating the length indicator 910 to determine how many segments are expected, requests the next data packet 806 or 812 by transmitting a start message to the responding terminal. At time t24 874, the answering terminal that received the “start” message from the requesting terminal starts transmitting the next transmission data packet 806 or 812, containing the next user data segment 902 and padding 911 (in this example, the next transmission data packet is the last data packet) . At time t25 875, the responding terminal that has received the ACK message stops its data transmission. One skilled in the art will understand that the interactions described herein are symmetrical, whereby the interrogating and responding terminals can be either the Source Terminal 100 or the Destination Terminal 600. One skilled in the art will also appreciate that user data may span more than two transmission data packets 806 or 812.

27B is another exemplary interaction diagram of a transmission data request sequence and a transmission data response sequence in which a user data length is greater than a transmission packet size. In this example, after the first transmission data packet 806 or 812 is requested via the “Start” messages transmitted by the requesting terminal, subsequent transmission data packets 806 or 812 are automatically transmitted by the responding terminal based on the receipt of the ACK message from the requesting terminal. In this example, the requesting terminal does not send a Start message to initiate the transmission of a subsequent transmission data packet 806 or 812 from the responding terminal. At time t31 881, the answering terminal that received the ACK message stops transmitting the first data packet, then immediately starts transmitting the next transmission data packet 806 or 812, separated only by the synchronization sequence. At time t32 882, the requesting terminal that has received the synchronization sequence starts transmitting NACK messages until it successfully receives the transmission data packet 806 or 812. During t33 883, having successfully received the transmission data packet 806 or 812, the requesting terminal starts transmitting ACK messages. At time t34 884, the responding terminal receiving the ACK message stops transmitting the transmission data packet 806 or 812.

FIG. 27C is another exemplary interaction diagram of a transmission data request sequence and a transmission data response sequence in which the user data length is greater than the transmission packet size. In this example, after the first transmission data packet 806 or 812 is requested through the “Start” messages transmitted by the requesting terminal, the subsequent transmission data packets 806 or 812 are automatically transmitted by the responding terminal based on the receipt of the ACK message from the requesting terminal. In this example, the requesting terminal does not send a Start message to initiate the transmission of a transmission data packet 806 or 812 from the responding terminal, nor does the requesting terminal transmit NACK messages. At time t41 891, the answering terminal that received the ACK message stops transmitting the first data packet, then immediately starts transmitting the next transmission data packet 806 or 812, separated only by the synchronization sequence. During t42 892, having successfully received the transmission data packet 806 or 812, the requesting terminal starts transmitting ACK messages. As soon as the responding terminal receives ACK messages, it stops transmitting the transmission data packet 806 or 812.

Fig. 27D is another exemplary interaction diagram of a transmission data request sequence and a transmission data response sequence in which the user data length is greater than the transmission packet size. FIG. 27D is an alternative to the example interaction diagram shown in FIG. 27B. In the example of FIG. 27D, the time interval at t32 882 between the ACK message of the requesting terminal for the first user data segment 903 and the NACK for the next user data segment 902 is eliminated. This helps maintain timing in the responding terminal so that it does not need to be resynchronized with the synchronization sequence of the requesting terminal.

One skilled in the art will understand that the responding terminals can automatically transmit data packets subsequent to the first data packet without transmitting a synchronization sequence separator. In this case, the synchronization sequence is sent once before the first transmission data packet 806 or 812, then upon receiving the ACK messages, the answering terminal automatically transmits the subsequent data packet without sending the synchronization. One skilled in the art will also understand that a length indicator 910 could also be transmitted with other data segments in addition to the first.

In the interaction schemes disclosed herein, error conditions may exist that need to be answered and that must be handled in a predetermined manner. The following sections provide examples for handling error conditions that correspond to the interaction patterns disclosed here. In each example, the error state is presented along with the corresponding response description. One skilled in the art will understand that the error handling described here can be applied equally to the source or destination terminal in both unidirectional and bidirectional embodiments.

An exemplary error condition occurs when the Source Terminal does not detect a transmitted synchronization preamble. In an exemplary response, the Source Terminal delays the transmission of the MSD message until a predetermined number of synchronization preambles are detected.

Another exemplary error condition occurs when the Source Terminal incorrectly detects a synchronization preamble. In the exemplary response, the Source Terminal delays the transmission of the MSD message until a predetermined number of detected synchronization preambles results in the same sample bias.

Another exemplary error condition occurs when the Source Terminal falsely detects a synchronization preamble, although in reality there was not one transmitted. In the sample response, the Source Terminal ignores falsely detected synchronization preambles. The source Terminal could initiate MSD transmission only if the predetermined number of detected synchronization preambles led to the same estimate of the sample offset.

Another exemplary error condition occurs when the Destination Terminal does not detect a transmitted synchronization preamble. In the example response, the Destination Terminal does not start to decode the MSD message, but continues to transmit Start messages to initiate the Source Terminal to re-initiate the MSD transmission after a predetermined number of Start messages have been received (including the synchronization preamble sequence).

Another exemplary error condition occurs when the Destination Terminal incorrectly detects a synchronization preamble. In the example response, the Destination Terminal decodes the received MSD data incorrectly for all versions of redundancy. Based on incorrectly decoded data, the Destination Terminal may re-initiate the transmission of the MSD by sending a “Start” message to the Source Terminal.

Another exemplary error condition occurs when the Destination Terminal falsely detects a synchronization preamble, although in reality there was not one transmitted. There is no answer, since the probability of this case is very low. The destination terminal does not begin to track its received signal while it waits for the synchronization preamble from the Source Terminal.

Another exemplary error condition occurs when the Source Terminal misinterprets the “Start” message as a NACK message. In an exemplary response, if the MSD transmission has not started, the Source Terminal delays the transmission of the MSD until it receives the “Start” message. In another example answer, if the MSD transmission is currently ongoing, the Source Terminal delays the reinitialization of the transmission.

Another exemplary error condition occurs when the Source Terminal incorrectly understands the “Start” message as an ACK message. In the exemplary answer, if the MSD transmission did not start, the Source Terminal ignores any ACK message. In another exemplary answer, the Source Terminal ignores the ACK if previous messages were interpreted as a “Start” message. In another exemplary response, if the previous messages were NACK messages, the Source Terminal pauses itself and terminates the MSD transmission if the next message is also interpreted as an ACK. In yet another exemplary response, if the previous message was interpreted as an ACK, the Source Terminal terminates the MSD transmission erroneously. The probability of this event is low, however, if it does occur, the Destination Terminal may re-initiate the transmission again by sending a request with “Start” messages.

Another exemplary error condition occurs when the Source Terminal misunderstands the NACK message as a “Start” message. In the sample answer, one NACK, which is interpreted as “Start”, has no effect on MSD transmission. In another exemplary response, a series of NACK messages that are all interpreted as “Start” messages can cause the Source Terminal transmitter to re-initiate MSD. The destination terminal does not expect this and will not accept incoming data, understanding them as incorrectly decoded data. Based on incorrectly decoded data, the Destination Terminal may request that the Source Terminal re-initiate the transmission by sending a Start message.

Another exemplary error condition occurs when the Source Terminal misunderstands the NACK message as an ACK message. In the sample response, if the previous message was interpreted as a “Start” message, the Source Terminal ignores any ACK message. In another exemplary response, if the previous message was interpreted as a NACK message, the Source Terminal waits for another ACK. If the next message is not another ACK, the current ACK is ignored. In another exemplary response, if the previous message was also erroneously detected as an ACK message, the Source Terminal may complete the MSD transmission, although the Destination Terminal has not yet received the MSD correctly. The probability of this event is low, however, if it does occur, the Destination Terminal may re-initiate the transmission again by sending a request with “Start” messages.

Another exemplary error condition occurs when the Source Terminal incorrectly understands the ACK message as a “Start” message. In an example response, the Source Terminal would not interrupt the transmission of additional versions of MSD redundancy, since the usual condition for a crash is to receive a predetermined number of ACK messages. If more subsequent messages are interpreted as “Start” messages, the Source Terminal may re-initiate the MSD transmission. Ultimately, the Destination Terminal would stop sending messages. The Source Terminal would ultimately decide that the Destination Terminal no longer sends synchronization frames and would produce its own reset, thereby stopping further transmissions.

Another exemplary error condition occurs when the Source Terminal misunderstands the ACK message as a NACK message. In an example response, the Source Terminal would continue to transmit redundancy versions until the ACK messages were detected correctly. Ultimately, the Destination Terminal would stop sending messages. The Source Terminal would ultimately decide that the Destination Terminal no longer sends synchronization frames and would produce its own reset, thereby stopping further transmissions.

Another exemplary error condition occurs when the Source Terminal determines that the received message is unreliable. In an exemplary response, if the received messages are “Start” messages, the Source Terminal continues to count unreliable messages, but with a lower weighting factor than if the messages were received with a reliable definition. Subsequent event triggers based on the number of messages received will require a larger, predetermined number of untrusted messages received, as if the messages were received with a reliable definition. In another exemplary response, if the unreliable received messages are NACK messages or ACK messages, the Source Terminal may ignore the messages.

Another exemplary error condition occurs when the Destination Terminal is unable to detect the transmitted MSD due to noise or other channel distortion. In an exemplary response, after attempting to decode a predetermined number of redundancy versions, the Destination Terminal may request the Source Terminal to re-initiate the transmission by sending a Start message. In a re-triggered transmission, the Source Terminal may use a robust modulator that is less prone to noise and other channel distortions.

Another exemplary error condition occurs when the Destination Terminal cannot evaluate the wake-up signal correctly. In the example answer, if the Destination Terminal considers the detection of the wake-up signal unreliable, it selects the fast (or normal) modulation mode for the first sample over the demodulation of the MSD data. For any other set of predetermined number of received versions of MSD data redundancy, the Destination terminal may use robust modulation mode to demodulate the data.

Thus, disclosed herein are a device and method for reliable and efficient in-band data transmission through a speech codec in a wireless communication system. Those skilled in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, and symbols that may be mentioned throughout the foregoing description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof . In addition, although embodiments are described primarily from the point of view of a wireless communication system, the described techniques can be applied to other in-band data systems that are fixed (non-portable) or do not include a wireless channel.

Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in relation to the embodiments disclosed herein may be implemented as electronic hardware, software, or a combination of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above usually in terms of their functionality. Whether functionality such as hardware or software is implemented depends on the particular application and design constraints imposed on the entire system. Skilled artisans may implement the described functionality in varying ways to each particular application, but such implementation decisions should not be interpreted as deviating from the scope of the present invention.

The various illustrative logic blocks, modules, and circuits described in relation to the embodiments disclosed herein may be implemented or implemented using a general purpose processor, digital signal processor (DSP), custom integrated circuit (ASIC), field programmable gate array (FPGA) ) or another programmable logic device, a discrete logic element or transistor logic, a discrete hardware component, or any combination of them designed to make you olnit functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any standard processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in relation to the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of media known in the art. The media is connected to the processor so that the processor can read information from, and write information to, the media. In the alternative, the medium may be an integral part of the processor. The processor and media may reside in an ASIC. In the alternative, the processor and the medium may reside as discrete components in a user terminal.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited by the embodiments shown here, but should receive the broadest possible scope, not inconsistent with the principles and new features disclosed herein.

Claims (8)

1. A method for controlling transmissions of non-speech information of a source terminal through a speech codec from a destination terminal in an in-band communication system, the method comprising the steps of:
transmitting the “Start” signal from the destination terminal in a repeating manner, the “Start” signal containing a synchronization signal followed by the “Start” message, and instructing the source terminal to transmit a synchronization signal and a data message;
upon detecting a synchronization signal from the source terminal, the Start signal is stopped and a NACK signal is transmitted from the destination terminal, the NACK signal containing a synchronization signal followed by a NACK message, indicating an unsuccessful reception of the data message of the source terminal by the destination terminal, and issuing the command to the source terminal repeating transmit a data message in a manner;
upon detection of a successfully received data message of the source terminal, the NACK signal is stopped and the ACK signal is transmitted from the destination terminal, the ACK signal contains a synchronization signal, followed by the ACK message, and instructs the source terminal to stop transmitting data messages of the source terminal; and
after a predetermined number of ACK signals has been transmitted, transmission of the ACK signal is stopped. 2. The method of claim 1, wherein the successfully received data message of the source terminal is a data message verified by cyclic redundancy monitoring. 3. The method of claim 1, further comprising repeating steps based on transmitting NACK signals a predetermined number of times if a successfully received data message of a source terminal is not detected. 4. A device for controlling transmissions of non-speech information of a source terminal through a speech codec from a destination terminal in an in-band communication system, comprising:
CPU;
memory in electronic communication with the processor; and
instructions stored in memory, and the instructions are executed to perform the steps in which:
transmitting the “Start” signal from the destination terminal in a repeating manner, the “Start” signal containing a synchronization signal followed by the “Start” message, and instructing the source terminal to transmit a synchronization signal and a data message;
upon detecting the synchronization signal from the source terminal, the Start signal is stopped and a NACK signal is transmitted from the destination terminal, the NACK signal containing a synchronization signal followed by a NACK message, indicating an unsuccessful reception of the data message of the source terminal by the destination terminal, and issuing a command to the source terminal transmit the data message in a repeatable manner;
upon detection of a successfully received data message of the source terminal, the NACK signal is stopped and the ACK signal is transmitted from the destination terminal, the ACK signal contains a synchronization signal, followed by the ACK message, and instructs the source terminal to stop transmitting data messages of the source terminal; and
after a predetermined number of ACK signals has been transmitted, transmission of the ACK signal is stopped. 5. The device according to claim 4, in which the successfully received data message of the source terminal is a data message verified by cyclic redundancy monitoring. 6. The device according to claim 4, in which the memory further comprises instructions that are executable for repeating steps based on the transmission of NACK signals, a predetermined number of times if a successfully received data message of the source terminal is not detected. 7. A control device for transmitting non-speech information of the source terminal through the speech codec from the destination terminal in the in-band communication system, the device comprising:
means for repeatedly transmitting the “Start” signal from the destination terminal, wherein the “Start” signal contains a synchronization signal followed by a “Start” message and instructs the source terminal to transmit a synchronization signal and a data message;
means for stopping the transmission of the “Start” signal upon detection of a synchronization signal and transmitting the NACK signal from the destination terminal, the NACK signal containing a synchronization signal followed by a NACK message, indicating an unsuccessful reception of the data message of the source terminal by the destination terminal and issuing the command the terminal to repeatedly transmit a data message;
means for, upon detection of a successfully received data message of the source terminal, stop transmitting the NACK signal and transmit the ACK signal from the destination terminal, the ACK signal containing a synchronization signal followed by the ACK message, and instructing the source terminal to stop transmitting data messages of the original terminal; and
means for, so that after a predetermined number of ACK signals have been transmitted, stop transmitting the ACK signal. 8. The device according to claim 7, further comprising means for repeating steps based on transmitting NACK signals a predetermined number of times if a successfully received data message of the source terminal is not detected.

Images