CN100591163C - Method of implementing SCDMA system terminal-to-terminal direct communication and uses thereof - Google Patents
Method of implementing SCDMA system terminal-to-terminal direct communication and uses thereof Download PDFInfo
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Abstract
The invention provides a method of realizing the direct communication between terminals of a SCAMA system and the application of the method. The invention comprises the steps that each signal frame emitted by a sender terminal carries SYNC, and a receiver terminal obtains the synchronization with the sender terminal based on SYNC. Based on the synchronization established between the sender terminal and the receiver terminal, the receiver terminal receives and demodulates the signal frame from the sender terminal. The method of the invention makes full advantage of the prior SCDMA system technology and redesigns the prior physical layer frame structure of the SCAMA system, so as to realize the direct communication between terminals of the SCAMA system.
Description
Technical Field
The present invention relates to a method and application for realizing direct communication between terminals under the condition of no network signal coverage, particularly to a method and application for realizing direct communication between terminals of a Synchronous Code Division Multiple Access (SCDMA) system.
Background
With the development of communication technology, how to implement direct communication between terminals without network signal coverage becomes one of the concerns. In general, a direct communication method between terminals without network signal coverage is called a direct mode of talk-through (DMO) by a technician.
The DMO mode is allowed to enter only after the terminal exceeds the coverage range of the network signal. In addition, after entering the DMO mode, the terminal also periodically detects a base station signal, and detects whether the current terminal is covered by a network signal; when the terminal is covered by the network signal, the terminal is to be automatically restarted to the network mode, so as to avoid the interference of the DMO mode to the existing network. In addition, the terminal can also exit the DMO mode through human intervention.
When adopting DMO mode, user can set frequency point, service code channel (VCC code channel) and emission power to terminal through terminal interface; since the terminal will automatically store the related data set by the user, the user can execute the above setting operation at any time, as long as the user sets the frequency point, the VCC code channel and the transmission power of the terminal to be the same as those of other terminals in the same group Grouping Identifier (GID), in the case of no network signal coverage, as long as one of the terminals is required to enter the DMO mode, the other terminals in the same GID group can also enter the DMO mode. As shown in fig. 1, it is a schematic diagram of applications of DMO modes of multiple terminals in the prior art, where one terminal initiates a call in a manner of monitoring first and then sending, and other terminals in the same GID group can all listen to the call. In the DMO mode, a terminal in a receiving state is prohibited from originating an outgoing call so as not to collide with each other.
In summary, when there is no network signal coverage, the DMO mode is used to perform communication, thereby avoiding situations such as sudden communication interruption or incapability of contacting related personnel in an emergency due to no network coverage. In view of the above, how to enable a majority of SCDMA users to perform DMO mode communication when the terminals are not covered by SCDMA network signals, and how to implement DMO mode communication according to the existing physical layer frame structure (as shown in fig. 2) of the SCDMA system has become a problem that is urgently solved in the communication field at present.
Disclosure of Invention
The technical problem to be solved by the present invention is how to fully utilize the prior art of the SCDMA system, and realize the direct communication between the SCDMA system terminal and the terminal under the condition of no SCDMA network signal coverage, i.e. realize the DMO mode, thereby realizing the half-duplex communication or short message service between the SCDMA system terminals.
The basic idea of the invention is as follows: the signal frame transmitted by each frame of the terminal of the sending party carries a synchronization Symbol (SYNC), and the terminal of the receiving party obtains the synchronization with the terminal of the sending party according to the SYNC; on the basis that the receiving and transmitting sides establish synchronization, the receiving side terminal receives and demodulates the signal frame transmitted by the transmitting side terminal.
In order to achieve the above object, the present invention provides a method for implementing direct communication between a terminal of an SCDMA system and a terminal, wherein the terminal of the SCDMA system at least comprises a sender terminal and a receiver terminal, and the method mainly comprises the following steps:
step 1: a sender terminal transmits a signal frame carrying SYNC and GID according to a physical layer frame structure;
step 2: a plurality of receiving party terminals of the same GID establish synchronization with the sending party terminal through processing of firstly finding a guard band and then finding a correlation peak and a synchronization point;
and step 3: after the receiving terminal establishes synchronization with the sending terminal, the receiving terminal receives and demodulates the signal frame and simultaneously carries out synchronization maintenance;
wherein, the physical layer frame structure comprises the following components which are sequentially arranged from front to back:
SYNC, which occupies 4 symbols and has the content of 1, is used for enabling the receiving party terminal to obtain receiving synchronization, carrier recovery and time correction;
a reference symbol (REF) occupying 1 symbol, having a binary bit 10, and used as a reference symbol when the receiver terminal performs Differential Quadrature Phase Shift Keying (DQPSK) demodulation;
a frame sequence number (FN) occupying 3 symbols, the value being 0-63;
GID, occupying 8 symbols, and the content length is 2 bytes;
an identification Symbol (SW) occupying 1 symbol for identifying the information content loaded by the signal frame, wherein 00, 01, 10 and 11 sequentially represent that the signal frame is a voice signal or short message information, a null frame, a control signal and a reserved signal;
cyclic redundancy check bits (CRC), which occupy 3 symbols, for performing cyclic redundancy check on the FN, GID, and SW received by the receiver terminal;
a modulated voice signal or short message information (V) occupying 96 symbols, which is 192-bit data obtained by 1/2 convolution-coding 96-bit compressed data;
a guard field (G) occupying 12 symbols, the sender terminal not transmitting the guard field when transmitting the signal frame.
Further, the method further comprises: and the sender terminal sets a Walsh sequence according to the user requirement. Wherein the sender terminal modulates all contents in the physical layer frame structure using the set Walsh sequence; the receiving terminal demodulates the signal frame it receives using the set Walsh sequence. It should be noted that the related art of using Walsh sequences for modulation and demodulation in the present invention is the same as the modulation technique of the existing SCDMA system.
Further, the sender terminal first performs 1/2 convolution and interleaving processing on the modulated voice signal or short message information in the physical layer frame structure to improve the bearing capacity of DMO mode communication of the SCDMA system terminal to the complex and changeable channel condition, and then modulates all contents in the physical layer frame structure with the set Walsh sequence.
Further, in the step 2, the receiving terminal finds the guard band according to the following steps, that is, performs coarse synchronization:
1) the receiving terminal receives 130 symbols transmitted by the transmitting terminal, and obtains the energy of each symbol after the 130 symbols are subjected to direct current removal;
2) the receiving terminal obtains the maximum rising edge of the energy after smoothing the energy of each symbol, and the maximum rising edge is used as the initial position of the transmitting terminal for transmitting signals;
3) and the receiving party terminal adjusts the receiving starting time according to the starting position.
Further, in step 3, the receiving terminal performs synchronization maintenance according to the following steps: the receiving terminal searches for a fine synchronization point in the range of at least 30 chips before and after the last signal frame synchronization point; and the influence of co-channel interference and other factors is not required to be considered.
In order to achieve the above object, the present invention further provides a system for implementing direct communication between a SCDMA system terminal and a terminal, wherein the SCDMA system terminal at least comprises a sender terminal and a receiver terminal, and the receiver terminal at least comprises a modem (MDM) and a Main Control Unit (MCU), wherein the application mainly comprises the following steps:
step 1: the MDM is awakened by the MCU every 320ms and then is transferred to a resynchronization (Resync) state from a Sleep (Sleep) state;
step 2: the MDM searches synchronously and carries out state transition according to the search result; wherein,
if the MDM finds synchronization at the frequency point set by the MDM, the searched CRC is correct, and the searched GID is the same as the GID set by the MDM, the MDM is transferred to a Receiving (RX) state from a Resync state and simultaneously feeds back the search result to the MCU;
and if the MDM does not find synchronization at the frequency point set by the MDM, or the CRC of a plurality of signal frames is not correct in continuous demodulation, or the searched GID is different from the GID set by the MDM, the MDM feeds back the search result to the MCU, and carries out state transfer according to the command of the MCU.
Further, after the MDM transitions to an RX state, comprising:
1) the MDM receives and demodulates a signal frame sent by the sender terminal;
2) the MDM judges whether the MDM receives a Link release (Link _ release) command sent by the sender terminal, and meanwhile, the MCU judges whether the quality of a communication channel is poor; wherein,
if the MDM receives the Link _ release command, the MDM stops receiving a demodulation signal frame, sends the Link _ release command to the MCU, and then switches to a Sleep state; otherwise, the MDM continues to receive and demodulate the signal frame sent by the sender terminal;
if the MCU judges that the quality of a communication channel is poor and the MDM loses synchronization and receives and demodulates a plurality of continuous signal frames with incorrect CRC, the MDM is switched into a Resync state according to a Resync command sent by the MCU and finds out synchronization by expanding a synchronization searching range; otherwise, the MDM continues to receive and demodulate the signal frame sent by the sender terminal; wherein,
and if the MDM cannot find synchronization again after a plurality of continuous resynchronization, the MDM is switched into a Sleep state according to a Stop receiving (Stop _ RX) command sent by the MCU.
In order to achieve the above object, the present invention further provides a system for implementing direct communication between a SCDMA system terminal and a terminal, wherein the SCDMA system terminal at least comprises a MDM and a MCU, and the application mainly comprises the following steps:
step 1: after the MDM is awakened by the MCU, the MDM is transferred to a frequency sweeping (Scan _ freq) state from a Sleep state; wherein the time interval for the MDM to transition from the Sleep state to the Scan _ freq state is several minutes;
step 2: the MDM carries out frequency sweeping processing, feeds back a frequency sweeping result to the MCU, and then shifts to a Sleep state; wherein,
if the frequency sweeping result shows that no SCDMA network signal is covered, the MDM carries out state transfer according to the command of the MCU; otherwise, the sender terminal and the receiver terminal exit the mode of direct communication between the terminals.
Wherein the MDM in Sleep state is awakened by the MCU once every 320 ms.
Further, the MDM entering and exiting the Sleep state mainly comprises the following steps:
1) the MDM judges whether to enter a Sleep state according to a processing result after being awakened by the MCU; wherein,
the processing result after the MDM is awakened at least comprises: the MDM does not find synchronization at the frequency point set by the MDM, or CRC of a plurality of signal frames is not correct in continuous demodulation, or the searched GID is different from the GID set by the MDM; the MDM receives a Link _ release command sent by the sender terminal; the MDM receives a Stop _ TX command or a Stop _ RX command sent by the MCU; MDM finishes frequency sweep processing;
if the processing result after the MDM is awakened is one of the processing results, the MDM sends Sleep interrupt to the MCU and enters a Sleep state; otherwise, the MDM continues to perform corresponding processing according to the command sent by the MCU;
2) after receiving the sleep interruption, the MCU calculates the sleep time of the MCU, sets an initial value of a sleep timer (WaitTimer) of the MCU and starts the WaitTimer; the MCU enters a Sleep state after Sleep initialization;
3) after the WaitTimer is timed, the MCU is awakened;
4) the MCU sends a sleep wake-up interrupt to the MDM to wake up the MDM;
5) and the MDM is communicated with the MCU and carries out state transition according to a command sent by the MCU.
The method for realizing the direct communication between the SCDMA system terminal and the terminal realizes the direct communication between the SCDMA system terminal and the terminal by redesigning the prior physical layer frame structure of the SCDMA system on the basis of fully utilizing the prior SCDMA system technology and changing as little as possible. The invention modulates all contents in the reset SCDMA physical layer frame structure by the same set Walsh sequence through the sender terminal and performs the related operation of the received signal frame and the PN _ Walsh by the receiver terminal by using the set Walsh sequence, thereby providing convenience for the subsequent demodulation processing of the receiver terminal; the invention adopts the channel coding and decoding technology of convolution and interleaving, thereby well improving the bearing capacity of DMO mode communication of the SCDMA system terminal to the complex and changeable channel condition.
Drawings
Fig. 1 is a schematic diagram illustrating an application of a DMO mode of a plurality of terminals in the prior art;
FIG. 2 is a diagram of a conventional physical layer frame structure of the SCDMA system;
FIG. 3 is a 10 frame format diagram of the physical layer frame structure of the redesigned SCDMA system of the present invention;
FIG. 4 is a flow chart of a method for implementing direct communication between SCDMA system terminals;
FIG. 5 is a schematic diagram of an application of the method for implementing direct communication between terminals in SCDMA system;
fig. 6 is a schematic diagram of a sleep process according to the present invention.
Detailed Description
Specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
In the DMO mode, whether the receiving side terminal can find the synchronization information of the sending side terminal and keep synchronization with it is a key technology in the application of the DMO mode. The solution provided by the invention is that the signal frame transmitted by each frame of the sender terminal carries SYNC, and the receiver terminal obtains the synchronization with the sender terminal according to the SYNC; on the basis that the receiving and transmitting sides establish synchronization, the receiving side terminal receives and demodulates the signal frame transmitted by the transmitting side terminal.
The invention relates to a DMO mode of SCDMA system terminal, which has the following concrete function realization principle: after a SCDMA system terminal is pressed down a DMO mode one-press instant-talk (PTT) key, the terminal is switched into a TX state, voice signal coding modulation is carried out or short message information given by an upper layer is modulated and then transmitted into the air, signal frames transmitted by each frame carry SYNC and group GID information, other SCDMA system terminals in the same GID group find out the SYNC transmitted by a sender terminal through continuous detection and establish synchronization with the SYNC, the signal frames transmitted by the sender terminal are received and demodulated on the basis of the synchronization, and voice or the demodulated short message information is restored after decoding and transmitted to the upper layer for processing. In addition, the present invention does not specially design the PTT key for the SCDMA system terminal to implement DMO mode, but defines one existing key in the SCDMA system terminal as the PTT key.
In order to realize the direct communication between the SCDMA system terminal and the terminal, the invention redesigns the prior physical layer frame structure of the SCDMA system aiming at the application of the DMO mode. The 10 frame format of the physical layer frame structure of the SCDMA system redesigned in the present invention is shown in fig. 3, according to the above frame structure, in DMO mode, the sender terminal needs to transmit 116 symbols per frame, total 9.0625ms, and the other 12 symbols (i.e. G) are not transmitted.
In order to fully utilize the existing SCDMA technology, the modulation and demodulation mode in the DMO mode of the SCDMA system terminal still uses the DQPSK of the existing SCDMA system, wherein, the vocoder in the DMO mode of the SCDMA system terminal still selects G.729D, the voice rate is 6.4K and BCH coding is added; the decoding mode of the receiving terminal still adopts Viterbi decoding soft decision, and after simulation comparison, the differential demodulation method still adopts conjugate multiplication method. In addition, the mode of performing CRC check on the control part in the redesigned frame structure in the DMO mode of the SCDMA system terminal of the present invention is consistent with the mode of performing CRC check on the control part in the MUX1D frame structure in the existing SCDMA system, and both the modes are obtained by performing table lookup or xor on the useful information of 24 bits after REF and before CRC.
In order to facilitate the demodulation processing after the receiving terminal, an improvement point of the invention is that: the sender terminal may set a Walsh sequence according to the user's needs. Then in the subsequent modulation and demodulation operation, the terminal of the sending party uses the set Walsh sequence to modulate all the contents in the reset SCDMA physical layer frame structure; the receiving-side terminal demodulates the signal frame it received using the set Walsh sequence. It should be noted that the related art of using Walsh sequences for modulation and demodulation in the present invention is the same as the modulation technique of the existing SCDMA system. In this embodiment, the Walsh sequence may be specifically set according to the following steps: 1) a man-machine interface module (MMI module) of the sender terminal records the serial number of the Walsh sequence input by a user and reports the serial number to the MDM of the sender terminal; wherein the serial number is an integer of 0-31; 2) the MDM searches out the Walsh sequence corresponding to the serial number from 32 Walsh sequences stored in the MDM according to the serial number; the Walsh sequence retrieved at this time is the Walsh sequence set by the sender terminal. In addition, if the user enters an incorrect sequence number, the sender terminal may wait for the user to enter again until the corresponding Walsh sequence is retrieved.
The following describes a specific implementation process of direct communication between terminals in the SCDMA system according to the present invention with reference to fig. 4.
Step 1: the sender terminal transmits a signal frame carrying SYNC and GID according to the reset physical layer frame structure;
the method specifically comprises the following steps: the terminal of the sender makes G.729 voice coding in the time slot of the current 9ms, then carries out 1/2 convolutional coding on 48Symbol voice or ECS packet obtained by voice coding, finally carries out interleaving processing, delays one frame, and uses the set Walsh sequence to modulate and transmit the result of the coding and interleaving in the next 9ms time slot of the sending terminal.
Step 2: a plurality of receiving party terminals of the same GID establish synchronization with a sending party terminal through processing of firstly finding a guard band and then finding a correlation peak and a synchronization point;
the method specifically comprises the following steps: 1) the receiver terminal finds the guard band, namely carries on the coarse synchronization;
in the DMO application mode of the SCDMA system terminal, the sender terminal transmits 116 symbols every 10ms, the rest 12 symbols are not transmitted, and the collision between terminal transmissions is not processed, but needs to depend on the operation skill of the user on the SCDMA system terminal working in DMO mode, so the algorithm for finding the guard band in the invention can be simplified compared with the prior SCDMA technology. In addition, in the DMO application mode of the SCDMA system terminal, the SCDMA system terminal will periodically (with a time interval of several minutes) detect the network signal, and once detecting that there is an available frequency point, i.e. there is SCDMA network coverage, the SCDMA system terminal will be switched to the network mode from the DMO mode, so that the protection band searching in the DMO application mode can be performed without considering the influence of the base station transmitting signal and the terminal transmitting signal, so that the determination condition is simplified.
To sum up, the algorithm for performing coarse synchronization in the DMO application mode of the SCDMA system terminal is basically the same as that of the existing SCDMA technology, that is: the receiving terminal receives 130 symbols transmitted by the transmitting terminal, and obtains the energy of each symbol after the 130 symbols are subjected to direct current removal; the receiving terminal obtains the maximum rising edge of the energy after smoothing the energy of each symbol, and the maximum rising edge is used as the initial position of the transmitting terminal for transmitting signals; and the receiving party terminal adjusts the receiving starting time according to the starting position.
2) The receiving terminal carries out the processing of finding out the correlation peak and the synchronization point, namely, the receiving terminal continues to carry out fine synchronization on the basis of the coarse synchronization;
when the invention redesigns the physical layer frame structure of the SCDMA system for realizing the application of the DMO mode, the invention particularly pays attention to the consistency of the number and the position of SYNC in the MUX1D frame structure in the prior SCDMA system, so that the basic algorithm flow of the processing of finding the relevant peak and the synchronization point by the terminal of the receiving party can be kept unchanged with the prior SCDMA technology.
And step 3: after the receiving terminal establishes synchronization with the sending terminal, the receiving terminal receives and demodulates the signal frame sent by the sending terminal and simultaneously carries out synchronization maintenance;
the receiving demodulation process specifically comprises the following steps: a receiving terminal receives the air signal of the frame in a 9ms receiving time slot and demodulates the air signal by using a Walsh sequence set by a sending terminal; and meanwhile, the receiving terminal de-interleaves the data received in the last frame, then performs Viterbi decoding, and then performs g.729 speech decoding.
Regarding to the synchronization maintenance, since the wireless channel between terminals is more complicated and changeable by the terminal in the DMO mode application of the SCDMA system terminal, the synchronization offset of each frame of signal frame is comparatively larger in the DMO mode receiving process, which requires that the receiving terminal searches for the synchronization point in a larger range when the receiving terminal performs the synchronization maintenance on each frame of signal frame, that is, the receiving terminal performs the synchronization maintenance specifically: the receiving terminal searches for a fine synchronization point in the range of 30 chips or more before and after the last signal frame synchronization point; and the influence of co-channel interference and other factors is not required to be considered.
In the application of DMO mode, in order to deal with complicated and bad transmission conditions, in the invention, a transmitting terminal carries out 1/2 convolution coding on speech and extended signaling (ECS) parts of air frames, and carries out interleaving processing after convolution. The method for coding and decoding the added channel can improve the bearing capacity of DMO mode communication of the SCDMA system terminal to the complex and changeable channel condition. Of course, the present invention is not limited to the channel coding and decoding technology of convolution and interleaving, and those skilled in the art can also adopt the channel coding and decoding technologies such as BCH and RS to improve the capability of DMO mode communication of the SCDMA system terminal to bear complex and variable channel conditions.
It should be noted that, in view of the difficulty of implementation, in order to achieve the goal of unifying the DMO technology and the existing SCDMA technology, the structure of the convolutional code adopted by the present invention is the same as that of the convolutional code adopted by the low-speed data service in the existing SCDMA technology, that is, (2, 1, 7). It should be understood by those skilled in the art that the present invention only uses the above-mentioned structure of the convolutional code for the purpose of uniformity, but the structure of the convolutional code in the present invention is not limited thereto.
In addition, the interleaving process described in the present invention specifically includes: the sender terminal performs data interleaving on two frames of signals one time and performs intra-frame interleaving on one frame of data after interleaving.
The following describes a specific application process of the direct communication between the SCDMA terminals according to the present invention with reference to fig. 5.
The application of the DMO mode of the SCDMA system terminal is mainly the state transition of MDM of the sender terminal and the receiver terminal. In the application of DMO mode of SCDMA system terminals, MDM states are divided into six states of Ready (Ready), Sleep, RX, TX, Resync, and ScanFreq. After the MDM is started, the system enters a Ready state, sends an MCU _ Ready command and a version number to the MCU, and then directly transfers to a Sleep state.
When the MDM is in Sleep state, it will be woken up by the MCU every 32 frames, i.e. 320 ms. The MDM decides to enter a sleep state by the MDM, and sends an interrupt to the MCU before sleeping so as to inform the MCU that the MDM enters the sleep state at the moment; after receiving the interrupt, the MCU needs to perform related processing such as timing. Sleep wake-up of the MDM is to be woken up by the MCU sending an interrupt.
And after the MDM is awakened by the MCU, the MDM immediately communicates with the MCU to acquire the command of the MCU, and the state transfer is carried out according to the command of the MCU. If the command of the MCU is MDMM _ ScanFreqDefault, the MDM is switched into a ScanFreq state; if the command of the MCU is MDMM _ Start _ TX at the moment, the MDM is switched into a TX state; otherwise, the MDM enters the Resync state. The MDMs of the sender terminal and the receiver terminal may switch to ScanFreq, TX, and Resync states according to the command of the MCU, and the ScanFreq, TX, and Resync states are executed for the MDM of the sender terminal or the MDM of the receiver terminal, respectively.
1) And if the MDM of the receiving party terminal is transferred to the Resync state, the MDM of the receiving party terminal needs to search for synchronization at a frequency point set by the MDM and carries out state transfer according to a search result. If the MDM of the receiving party terminal finds synchronization at the frequency point set by the receiving party terminal, the searched CRC is correct, and the searched GID is the same as the GID set by the receiving party terminal, the MDM of the receiving party terminal is transferred to an RX state from a Resync state and simultaneously feeds back the search result to an MCU of the receiving party terminal; if the MDM of the receiving party terminal does not find synchronization at the frequency point set by the MDM, or the CRC of a plurality of signal frames is not correct in continuous demodulation, or the searched GID is different from the GID set by the MDM, the MDM of the receiving party terminal feeds back the search result to the MCU of the receiving party terminal, and state transfer is carried out according to the command of the MCU.
2) If the MDM of the receiving party terminal is transferred to an RX state, the MDM of the receiving party terminal performs Viterbi decoding and G.729 voice decoding processing and simultaneously receives and demodulates a signal frame sent by the sending party terminal; in addition, the MDM of the receiving party terminal judges whether the MDM receives a Link _ release signaling packet sent by the sending party terminal, and meanwhile, the MCU of the receiving party terminal judges whether the quality of a communication channel is poor; wherein,
if the MDM of the receiving party terminal receives the Link _ release signaling packet, the MDM of the receiving party terminal stops receiving the demodulation signal frame, sends an MCU _ Link release command to the MCU and then switches to a Sleep state; otherwise, the MDM of the receiving party terminal continues to receive and demodulate the signal frame sent by the sending party terminal;
if the MCU of the receiving party terminal judges that the quality of the communication channel is poor, and the MDM of the receiving party terminal loses synchronization and receives and demodulates a plurality of continuous signal frames with incorrect CRC, the MDM of the receiving party terminal is switched into a Resync state according to an MDM _ Resync command sent by the MCU of the receiving party terminal, and synchronization is retrieved in a mode of expanding a synchronization searching range; otherwise, the MDM of the receiving party terminal continues to receive and demodulate the signal frame sent by the sending party terminal; if the MDM of the receiving party terminal cannot find synchronization after a plurality of times of continuous resynchronization, the MDM of the receiving party terminal is switched into a Sleep state according to a Stop _ RX command sent by the MCU of the receiving party terminal.
3) If the MDM of the terminal of the sender is transferred to a TX state, the MDM of the terminal of the sender needs to carry out convolutional coding and G.729 voice coding processing, and simultaneously, a modulated signal frame needs to be transmitted to the air; and directly switching to a Sleep state until the MDM of the terminal of the sender detects a Stop _ TX command sent by the MCU of the terminal of the sender.
4) If the MDM of the terminal of the sender or the terminal of the receiver is transferred to a ScanFreq state, the MDM needs to carry out frequency sweeping treatment according to a normal frequency sweeping method and flow in the prior SCDMA technology so as to timely detect whether the SCDMA network signal covers; after the frequency sweep is finished, the MDM needs to send an MCU _ Presyncresult command to the corresponding MCU so as to feed back the frequency sweep result to the MCU, and then the MCU is switched into a Sleep state; wherein,
if the frequency sweeping result shows that no SCDMA network signal is covered, the MDM carries out state transfer according to the command of the MCU; otherwise, the sender terminal and the receiver terminal exit the DMO mode.
Because the DMO mode is applied under the condition of no SCDMA network signal coverage, the SCDMA system terminal wakes up from sleep every 32 frames, and needs to search for synchronization from finding the guard band again, and thus, judges whether there is other terminal transmitting signal currently, so that the normal sleep flow like the existing SCDMA technology is not needed, but the flow can be similar to the deep sleep flow.
The following describes the sleep flow in the specific application process of the SCDMA system according to the present invention in which the terminal and the SCDMA terminal communicate directly with each other, with reference to fig. 6. The sleep flow in the DMO application mode may be simplified as follows:
1) the MDM judges whether to enter a Sleep state according to a processing result after the MDM is awakened by the MCU; wherein, the processing result after the MDM is awakened at least comprises: the MDM does not find synchronization at the frequency point set by the MDM, or CRC of a plurality of signal frames is not correct in continuous demodulation, or the searched GID is different from the GID set by the MDM; the MDM receives a Link _ release command sent by the sender terminal; the MDM receives a Stop _ TX command or a Stop _ RX command sent by the MCU; the MDM finishes frequency sweeping processing (whether available frequency points are swept or not);
2) if the processing result after the MDM is awakened is one of the processing results, before sleeping, the MDM stores data to be communicated with the MCU into the DPRAM, sends a sleep interrupt to the MCU and informs the MCU that the MCU is to enter a sleep state; in addition, the MDM immediately enters a Sleep state after stopping part of hardware resources controlled by the MDM, such as a radio frequency analog-to-digital/digital-to-analog converter (AD/DA), a multimedia digital signal coder-decoder (CODEC), and the like; otherwise, the MDM continues to perform corresponding processing according to the command sent by the MCU;
3) after receiving the sleep interruption sent by the MDM, the MCU calculates the sleep time of the MCU, sets the initial value of the WaitTimer and starts the WaitTimer; the MCU enters a Sleep state after Sleep initialization;
wherein, MCU sets up WaitTimer's initial value and starts WaitTimer and specifically does: setting preset values AUX0_ TIME and AUX1_ TIME; the values of AUX _ ON0 and AUX _ ON1 automatically go low; turning off the radio frequency power supply and the radio frequency clock;
in addition, the MCU specifically performs sleep initialization as follows: after each task of the MCU enters a sleep state, setting a corresponding sleep event group mark; the Power Saving (PS) task is responsible for detecting the sleep event group, and when all tasks are in the sleep state, the MCU is controlled to enter the sleep state;
4) when WaitTimer is reduced to a preset value AUX0_ TIME, the WaitTimer automatically starts a radio frequency power supply;
5) when WaitTimer is reduced to a preset value AUX1_ TIME, the WaitTimer automatically starts a radio frequency clock;
6) when the WaitTimer is finished, the WaitTimer sends an interrupt to wake up the MCU;
7) after the MCU is awakened, starting a DSP clock, then sending a sleep awakening interrupt to the MDM, and awakening the MDM;
8) and after being awakened, the MDM completes operations such as initializing radio frequency, locking frequency and the like, then immediately communicates with the MCU to acquire the command of the MCU, and carries out state transfer according to the command sent by the MCU.
It should be noted that modifications and adaptations may occur to those skilled in the art without departing from the principles of the present invention and should be considered within the scope of the present invention.
Claims (12)
1. A method for realizing SCDMA system terminal and terminal direct communication, the SCDMA system terminal includes the sender terminal and the receiver terminal at least, characterized by that, it includes:
step 1: a sender terminal transmits a signal frame carrying a synchronization symbol and a cluster grouping identifier according to a physical layer frame structure;
step 2: a plurality of receiving party terminals of the same cluster grouping identifier establish synchronization with the sending party terminal through processing of firstly finding a guard band and then finding a correlation peak and a synchronization point;
and step 3: after the receiving terminal establishes synchronization with the sending terminal, the receiving terminal receives and demodulates the signal frame and simultaneously carries out synchronization maintenance;
wherein, the physical layer frame structure comprises the following components which are sequentially arranged from front to back:
the synchronous symbols occupy 4 symbols, the content of which is 1, and are used for enabling the receiving party terminal to obtain receiving synchronization, carrier recovery and time correction;
reference symbols, which occupy 1 symbol, have binary bit 10 content, and are used as reference symbols when the receiving terminal demodulates;
the frame serial number occupies 3 symbols and has a value of 0-63;
cluster grouping identification, which occupies 8 symbols, and the content length is 2 bytes;
the identification symbol occupies 1 symbol and is used for identifying the information content loaded by the signal frame, wherein 00, 01, 10 and 11 sequentially indicate that the signal frame is a voice signal or short message information, a null frame, a control signal and a reserved signal;
a cyclic redundancy check bit, which occupies 3 symbols and is used for performing cyclic redundancy check on the frame sequence number, the cluster grouping identifier and the identification symbol received by the receiver terminal;
the modulated voice signal or short message information occupies 96 symbols;
and a guard field occupying 12 symbols, the guard field not being transmitted by the sender terminal when transmitting the signal frame.
2. The method of claim 1, further comprising: and the sender terminal sets a Walsh sequence according to the user requirement.
3. The method of claim 2, wherein the sender terminal modulates all contents in the physical layer frame structure using the set Walsh sequence.
4. The method of claim 2, wherein the receiving terminal demodulates its received signal frame using the set Walsh sequence.
5. The method of claim 3, wherein the transmitting terminal firstly performs 1/2 convolution and interleaving on the modulated voice signal or short message information in the physical layer frame structure, and then modulates all contents in the physical layer frame structure by using the set Walsh sequence.
6. The method of claim 1, wherein in the step 2, the receiving terminal finds the guard band according to the following steps, i.e. coarse synchronization is performed:
1) the receiving terminal receives 130 symbols transmitted by the transmitting terminal, and obtains the energy of each symbol after the 130 symbols are subjected to direct current removal;
2) the receiving terminal obtains the maximum rising edge of the energy after smoothing the energy of each symbol, and the maximum rising edge is used as the initial position of the transmitting terminal for transmitting signals;
3) and the receiving party terminal adjusts the receiving starting time according to the starting position.
7. The method according to claim 1, wherein in the step 3, the receiving terminal performs synchronization maintenance according to the following steps:
the receiving terminal searches for the fine synchronization point within a range of at least 30 chips before and after the synchronization point of the previous signal frame.
8. A system for realizing SCDMA system terminal and terminal direct communication, the SCDMA system terminal includes sender's terminal and take over party's terminal at least, and the take over party's terminal includes modem and master control unit at least, characterized by that, including:
step 1: the modem is awakened by the main control unit every 320ms and then is transferred from a sleep state to a resynchronization state;
step 2: the modem searches for synchronization and carries out state transition according to a search result; wherein,
if the modem finds synchronization at the frequency point set by the modem, the searched cyclic redundancy check bit is correct, and the searched cluster group identifier is the same as the cluster group identifier set by the modem, the modem is transferred to a receiving state from a resynchronization state, and the searching result is fed back to the main control unit;
if the modem does not find synchronization at the frequency point set by the modem, or the cyclic redundancy check bits of a plurality of continuously demodulated signal frames are not correct, or the searched cluster group identification is different from the cluster group identification set by the modem, the modem feeds back the search result to the main control unit, and performs state transition according to the command of the main control unit.
9. The system of claim 8, after the modem transitions to the receive state, comprising:
1) the modem receives and demodulates a signal frame sent by the sender terminal;
2) the modem judges whether the modem receives a link release command sent by the sender terminal, and meanwhile, the main control unit judges whether the quality of a communication channel is poor; wherein,
if the modem receives the link release command, the modem stops receiving a demodulation signal frame, sends the link release command to the main control unit and then switches to a sleep state; otherwise, the modem continues to receive and demodulate the signal frame sent by the sender terminal;
if the main control unit judges that the quality of a communication channel is poor and the cyclic redundancy check bits of a plurality of continuous signal frames which are subjected to synchronization loss and receiving demodulation of the modem are incorrect, the modem is switched into a resynchronization state according to a resynchronization command sent by the main control unit and finds synchronization by expanding a synchronization search range; otherwise, the modem continues to receive and demodulate the signal frame sent by the sender terminal; wherein,
and if the modem cannot find synchronization again after a plurality of times of continuous resynchronization, the modem is switched into a sleep state according to a receiving stopping command sent by the main control unit.
10. A system for realizing SCDMA system terminal and terminal direct communication, the SCDMA system terminal includes modem and master control unit at least, characterized by that, including:
step 1: after the modem is awakened by the main control unit, the modem is transferred from a sleep state to a frequency sweeping state; the time interval for the modem to be transferred from the sleep state to the frequency sweeping state is several minutes;
step 2: the modem carries out frequency sweeping processing, feeds back a frequency sweeping result to the main control unit and then shifts to a sleep state; wherein,
if the frequency sweeping result shows that no SCDMA network signal is covered, the modem carries out state transfer according to the command of the main control unit; otherwise, the sender terminal and the receiver terminal exit the mode of direct communication between the terminals.
11. The system according to claim 8 or 10, characterized in that a modem in sleep state is woken up by the master control unit once every 320 ms.
12. The system of claim 8 or 10, wherein the modem entering and exiting the sleep state primarily comprises:
1) the modem judges whether to enter a sleep state according to a processing result after being awakened by the main control unit; wherein,
the processing result after the modem is awakened at least comprises: the modem finds no synchronization at the frequency point set by itself, or the cyclic redundancy check bits of a plurality of continuously demodulated signal frames are not correct, or the searched cluster grouping identification is different from the cluster grouping identification set by itself; the modem receives a link release command sent by the sender terminal; the modem receives a command for stopping sending or receiving sent by the main control unit; the modem finishes frequency sweeping processing;
if the processing result after the modem is awakened is one of the processing results, the modem sends a sleep interrupt to the main control unit and enters a sleep state; otherwise, the modem continues to perform corresponding processing according to the command sent by the main control unit;
2) after receiving the sleep interruption, the main control unit calculates the sleep time of the main control unit, sets the initial value of a sleep timer of the main control unit and starts the sleep timer; the main control unit enters a sleeping state after sleep initialization;
3) after the sleep timer finishes timing, waking up the main control unit;
4) the master control unit sends a sleep wakeup interrupt to the modem to wake up the modem;
5) the modem is communicated with the main control unit and carries out state transition according to the command sent by the main control unit.
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| US20210105124A1 (en) * | 2017-06-29 | 2021-04-08 | Qualcomm Incorporated | Providing protection for information delivered in demodulation reference signals (dmrs) |
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| CN101662733B (en) * | 2009-09-29 | 2013-03-27 | 中兴通讯股份有限公司 | Method of applying offline direct mode operation (DMO) and device thereof |
| CN102958097B (en) * | 2011-08-23 | 2016-08-03 | 华为技术有限公司 | Realize synchronizing between subscriber equipment and the method and apparatus of perception |
| CN103220782B (en) | 2012-01-19 | 2017-08-18 | 华为技术有限公司 | A kind of determination method, system and equipment for transmitting subframe |
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| US20210105124A1 (en) * | 2017-06-29 | 2021-04-08 | Qualcomm Incorporated | Providing protection for information delivered in demodulation reference signals (dmrs) |
| US11671222B2 (en) * | 2017-06-29 | 2023-06-06 | Qualcomm Incorporated | Providing protection for information delivered in demodulation reference signals (DMRS) |
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Assignee: SHENZHEN XINWEI TELECOMM TECHNOLOGY CO., LTD. Assignor: Xinwei Communications Technological Co., Ltd., Beijing Contract record no.: 2011110000200 Denomination of invention: Method of implementing SCDMA system terminal-to-terminal direct communication and uses thereof Granted publication date: 20100217 License type: Exclusive License Open date: 20080416 Record date: 20111226 |
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