JP4590008B2 - Mobile radio communication apparatus and communication processing method - Google Patents

Description

  The present invention relates to a mobile radio communication apparatus and a communication processing method.

  There is known a mobile radio communication system that enables radio communication using radio channels such as a control channel, a physical communication channel, and a direct communication channel. Here, the control channel is a radio channel used between the base station and the mobile station in order to perform outgoing and incoming calls and other communication control in the mobile station. A physical communication channel is used for each mobile station to communicate with or communicate with a base station via a mobile communication network with another mobile station or a fixed terminal (for example, a fixed telephone or a network-connected computer terminal). It is a radio channel used between mobile stations. The direct communication channel is a radio channel used for each mobile station to directly perform a call or data communication with another mobile station without going through a base station.

  In digital communication using such a wireless channel, transmission data may be transmitted as a predetermined frame structure (for example, Non-Patent Document 1). 9 shows ARIB STD-T61, which is a standard for narrowband digital radio systems, as the second volume p. 115 shows frame formats of a control channel (physical control channel), a physical communication channel, and a direct communication channel defined in 115-116.

  Here, the synchronization word used for frame synchronization often has the same length in any of the control channel, physical communication channel, and direct communication channel. In the example shown in FIG. 9, all the synchronization words are fixed to 20 bits. A fixed-length synchronization word is also defined in ARIB STD-27, which is a standard for PDC (Personal Digital Cellular) which is a mobile telephone system. By unifying the synchronization words to the same length in this way, the detection of frame synchronization in digital signal processing can be shared by each channel, and the processing can be simplified. For example, when shifting from a control channel to a physical communication channel or when starting a direct communication channel, a special frame for synchronization (synchronization burst) is used to improve synchronization performance. Is done. In this case, a synchronization word longer than usual (for example, having 32 bits) is used.

  Various methods are known as methods for capturing a synchronization word in a communication device on the receiving side. For example, many methods are used for acquiring a synchronization word by specifying a correlation value between a synchronization word known on the receiving side and a baseband signal waveform demodulated from a received signal by a predetermined calculation process. According to the ARIB STD-T61 standard described above, when one frame is 40 msec (milliseconds) and a 20-bit synchronization word is received twice, it is determined that synchronization is established. For this reason, a synchronization word for 40 bits is used in a period of 80 msec until synchronization is established.

  In a micro cell system such as a PDC, the control channel and the physical communication channel are not always provided by the same base station. Therefore, it is technically difficult to always keep the timing between the control channel and the physical communication channel constant. Partly due to these facts, the above-mentioned standard does not particularly define the frame timing between the control channel and the physical communication channel.

  Further, when wireless communication is performed using a physical communication channel or a direct communication channel, it is required to quickly establish a communication link between the transmission side and the reception side. When a delay occurs in the establishment of the communication link, there arises a problem that, for example, the head is cut off in a call. In addition, when digital audio data is transmitted / received, the amount of information becomes enormous, and the amount of information to be transmitted on the physical communication channel or the direct communication channel may increase compared to the control channel. A QPSK (Quadrature Phase Shift Keying) modulation method is known as a modulation method with good transmission efficiency, and is adopted in mobile radio communication systems compliant with PDC and ARIB STD-T61 standards. However, it is also known that the QPSK modulation scheme is difficult to cover a wide area with one base station.

“Narrowband Digital Communication System (SCPC / FDMA) Standard ARIB STD-T61 Version 1.0 Volume 2”, May 27, 1999, p. 115-117, p. 171-174

  In a mobile radio communication system in which data communication is performed, in order to improve the communication speed, the bandwidth of the occupied frequency is being increased. On the other hand, in wireless devices and the like for which voice calls are mainly used, the bandwidth of wireless channels is being narrowed in order to improve frequency utilization efficiency. In a wireless channel whose bandwidth has been narrowed, the information transmission rate (capacity) inevitably decreases. Therefore, it is preferable that the length (number of bits) of the synchronization word is short (the number of bits is small). However, if the synchronization word is shortened, the frame synchronization performance deteriorates. In particular, when there is a lot of noise on the radio channel, there is a problem that the rate at which synchronization can be normally established is reduced, causing an increase in false synchronization.

  In a mobile radio communication system installed in a suburb of the United States or the like, a high output power amplifier may be used for a transmission output stage in a base station so that a single base station can cover a wide area. In a modulation scheme in which the envelope of the modulated wave signal is non-linear (for example, QAM; Quadruple Amplitude Modulation), it is necessary to perform amplification using only a portion that can maintain linearity in the input / output characteristics of the power amplifier. In this case, the power efficiency is reduced. Therefore, it is preferable to use a modulation scheme such as FM (Frequency Modulation) or PM (Phase Modulation) in which the envelope of the modulated wave signal is a substantially straight line. However, the FSK (Frequency Shift Keying) modulation method has about half the transmission efficiency compared to the case of using the QPSK modulation method, and the information transfer rate (capacity) decreases. Also in this case, it is preferable that the length of the synchronization word is short. However, if the synchronization word is shortened, the above-described problem occurs.

  The present invention has been made in view of the above situation, and it is possible to quickly establish a communication link by shortening the length of the synchronization word and shortening the time required for establishing synchronization, and synchronization with good accuracy. It is an object of the present invention to provide a mobile radio communication apparatus and the like that enable detection.

In order to achieve the above object, a mobile radio communication apparatus according to the first aspect of the present invention provides:
Demodulating means for receiving a radio signal transmitted on a predetermined radio channel and demodulating a baseband signal;
Frame synchronization means for obtaining frame synchronization by detecting at least a predetermined synchronization word from the symbol sequence represented by the baseband signal demodulated by the demodulation means;
The frame synchronization means, when demodulating a baseband signal from a radio signal transmitted on a control channel provided from a base station among the radio channels by the demodulation means, has a predetermined code at the head of each frame. A synchronization word consisting of a pattern is placed, but the synchronization status is re-synchronized from the initial synchronization and the resynchronization from a plurality of frames where a post field containing a preword consisting of a code pattern different from the synchronization word is placed at the end of each frame Depending on whether the synchronization is maintained, the first detection operation for detecting only the synchronization word and the second detection operation for detecting both the synchronization word and the preword are performed.
The frame synchronization means further demodulates a baseband signal from a radio signal transmitted on a communication channel directly with another mobile station among the radio channels by the demodulation means, Preamble including a preword is arranged at the head of the frame, and depending on whether the synchronization state is initial synchronization, resynchronization or synchronization maintenance from a plurality of frames in which a synchronization word is arranged in each frame Performing either the first detection operation or the second detection operation;
It is characterized by that.

  The frame synchronization means, when demodulating a baseband signal from a radio signal transmitted on the direct communication channel by the demodulation means, a synchronization word when the synchronization state is either initial synchronization or resynchronization Frame synchronization is acquired when a sync word can be detected multiple times, or when a sync word and pre-word can be detected once, or when the sync status is synchronized, the sync word can be detected once. Judge that it was made.

In order to achieve the above object, a communication processing method according to the second aspect of the present invention provides:
A communication processing method by a mobile radio communication apparatus that performs radio communication with either a base station or another mobile station by transmitting / receiving a radio signal transmitted on a predetermined radio channel,
A demodulation step of receiving a radio signal and demodulating a baseband signal;
A frame synchronization step of acquiring frame synchronization by detecting at least a predetermined synchronization word from the symbol sequence represented by the baseband signal demodulated in the demodulation step;
The frame synchronization step includes:
When the baseband signal is demodulated from the radio signal transmitted on the control channel provided from the base station among the radio channels in the demodulation step, a synchronization word consisting of a predetermined code pattern is formed at the head of each frame. On the other hand, at the end of each frame, the synchronization status is either initial synchronization, resynchronization, or synchronization maintenance from a plurality of frames in which a post field including a preword having a code pattern different from the synchronization word is arranged. Depending on whether there is a first detection operation that detects only the synchronization word or a second detection operation that detects both the synchronization word and the preword,
When the baseband signal is demodulated from the radio signal transmitted directly on the communication channel with other mobile stations in the radio channel in the demodulation step, a preword is included at the beginning of the frame at the start of transmission. From the plurality of frames in which the preamble is arranged and the synchronization word is arranged in each frame, the first detection operation and the first detection operation are performed according to whether the synchronization state is initial synchronization, resynchronization, or synchronization maintenance. Perform one of the two detection operations,
It is characterized by that.

  In the frame synchronization step, when the baseband signal is demodulated from the radio signal transmitted on the direct communication channel in the demodulation step, the synchronization state is either initial synchronization or resynchronization. Frame synchronization when the sync word can be detected multiple times, or when the sync word and pre-word can be detected once, or when the sync status is synchronized, the sync word can be detected once. Is determined to have been acquired.

  According to the present invention, it is possible to quickly establish a communication link and perform synchronization detection with good accuracy.

It is a figure which shows the example of 1 structure of the mobile radio | wireless communications system which concerns on embodiment of this invention. It is a figure which shows an example of the frame structure in the digital data transmitted by each of a control channel, a physical communication channel, and a direct communication channel. It is a figure which shows the example of 1 structure of a synchronous detection circuit. It is a figure which shows the example of 1 structure of a radio | wireless communication control apparatus. It is a figure which shows the example of a setting for acquiring a synchronization in a mobile radio | wireless communication apparatus. It is a figure for demonstrating the specific example of the arithmetic processing performed in order to establish a synchronization. It is a figure for demonstrating the specific example of the operation | movement which acquires synchronization using only a synchronization word. It is a figure for demonstrating the specific example of the operation | movement which acquires a synchronization using both a preword and a synchronous word. It is a figure which shows an example of the conventional frame format.

  Hereinafter, mobile radio communication system 100 according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, for example, the mobile radio communication system 100 includes a mobile radio communication apparatus 101 as a plurality of mobile stations, and a radio communication control apparatus 102 as at least one (generally a plurality of) base stations. Is included. In FIG. 1, two mobile radio communication apparatuses 101 and one radio communication control apparatus 102 are shown as an example. For example, the mobile radio communication system 100 may be a large-zone land mobile radio communication system in which the radio communication control apparatus 102 as a base station covers a wider area than a micro cell system such as a PDC.

  Each mobile radio communication apparatus 101 transmits / receives a radio frequency (RF) signal to / from another radio communication control apparatus 102 as a base station, so that each mobile radio communication apparatus 101 and radio communication control apparatus 102 can transmit / receive radio frequency (RF) signals. Voice communication (conversation) is possible with other communication terminal devices connected to the network. In the wireless communication between each mobile wireless communication device 101 and the wireless communication control device 102, the control channel 110 and the physical communication channel 111 are used. In addition, each mobile radio communication device 101 uses the direct communication channel 112 to directly transmit and receive RF signals to and from other mobile radio communication devices 101 without going through the base station, thereby making a voice call, etc. Can also be done.

  On radio channels such as the control channel 110, the physical communication channel 111, and the direct communication channel 112, an RF signal modulated by a predetermined digital modulation method (for example, 4-level FSK [Frequency Shift Keying]) is transmitted and received. Digital data having a predetermined frame structure is transmitted. FIGS. 2A to 2C are diagrams showing examples of frame structures in digital data transmitted through the control channel 110, the physical communication channel 111, and the direct communication channel 112, respectively.

  Digital data having the frame structure shown in FIGS. 2A and 2B is transmitted to each mobile radio communication apparatus 101 from the radio communication control apparatus 102 serving as a base station. Here, it is assumed that the frame length in the digital data transmitted from the wireless communication control apparatus 102 is 80 msec and the communication speed is 4800 bps. As shown in FIG. 2A, on the control channel 110, a frame in which a 20-bit synchronization word SW having a predetermined code pattern is arranged at the beginning of the frame and a 20-bit post field PF is arranged at the end. Structured digital data is transmitted. In this configuration, the communication speed is halved and the frame length is doubled compared to the ARIB STD-T61 standard, while the synchronization word SW is halved at 20 bits per 80 msec. ing.

  Using the control channel 110, the wireless communication control apparatus 102 continuously transmits digital data having a frame structure as shown in FIG. 2A over a plurality of frames. For this reason, the post field PF in the previous frame is arranged in front of the synchronization word SW of each frame.

  As shown in FIG. 2B, on the physical communication channel 111, the synchronization word SW is arranged at the head of the frame, but unlike the control channel 110, digital data having a frame structure that does not include the post field PF. Is transmitted. As shown in FIG. 2C, on the direct communication channel 112, a 20-bit preamble PA is arranged at the beginning of the frame at the start of transmission, and follows the preamble PA at the beginning of each frame (in the frame at the start of transmission). The frame-structured digital data in which the 20-bit synchronization word SW is arranged is transmitted.

  The post field PF included in the frame shown in FIG. 2 (A) and the preamble PA included in the frame shown in FIG. 2 (C) are composed of a preword PW having the same code pattern. For example, the preword PW may be determined in advance as a code pattern different from the synchronization word SW. As an example, the post field PF and the preamble PA only need to be configured by the same preword PW. As another example, the pre-word PW that is the same code may be included in the last few bits of the post field PF and the preamble PA.

  When each mobile radio communication apparatus 101 performs communication via a base station, an FDMA (Frequency Division Multiple Access) system that assigns a physical communication channel 111 from a control channel 110 provided by a radio communication control apparatus 102 that is a base station is used. It is done. On the other hand, when a plurality (for example, two) of mobile radio communication apparatuses 101 communicate directly without going through a base station, an unassigned SCPC (Single Channel Per Carrier) system is used.

  Each mobile radio communication apparatus 101 has substantially the same configuration. For example, as shown in FIG. 1, the baseband signal processing unit 1, the transmission processing unit 2, the antenna 3, and the reception processing are performed. A section 4 and a transmission / reception separating section 5 are provided.

  The baseband signal processing unit 1 inputs transmission data from the outside to generate a baseband signal for digital transmission, or inputs a baseband signal from the reception processing unit 4 to extract reception data and output it to the outside To do. Here, the transmission data input to the baseband signal processing unit 1 may be taken from the outside of the mobile radio communication apparatus 101, a data processing unit (not shown) in the mobile radio communication apparatus 101, or the like It may be generated by. For example, the mobile wireless communication apparatus 101 may include a data processing unit that generates information data indicating sound and images captured from the outside.

  The transmission processing unit 2 is for generating a radio signal for transmission corresponding to the baseband signal for digital transmission generated by the baseband signal processing unit 1. For example, the transmission processing unit 2 performs predetermined digital modulation (for example, four-value FSK [Frequency Shift Keying] modulation) in response to a baseband signal for digital transmission. The transmission processing unit 2 performs frequency conversion (up-conversion) and power amplification of the modulated wave signal generated by the modulation operation, and then supplies the antenna 3 via the transmission / reception separation unit 5 to move A wireless signal is transmitted from the wireless communication apparatus 101.

  The reception processing unit 4 performs low-noise amplification, frequency conversion (down-conversion), etc. on the signal received by the antenna 3, and then performs predetermined digital demodulation to reproduce the baseband signal. The baseband signal reproduced by the reception processing unit 4 is supplied to the baseband signal processing unit 1. The transmission / reception separating unit 5 is a duplexer that prevents the output of the transmission processing unit 2 from wrapping around the reception processing unit 4 or prevents the input to the reception processing unit 4 from wrapping around the transmission processing unit 2 side. .

  In the above configuration, the baseband signal processing unit 1 includes the synchronization detection circuit 10 to which the baseband signal from the reception processing unit 4 is input. FIG. 3 is a diagram illustrating a configuration example of the synchronization detection circuit 10. As shown in FIG. 3, the synchronization detection circuit 10 includes a sampling circuit 11, an A / D (Analog-to-Digital) converter 12, a frame memory 13, a synchronization word storage unit 14, and a preword storage unit 15. , A synchronization calculation unit 16 and an operation control unit 17 are provided.

  The sampling circuit 11 is for sampling the baseband signal input from the reception processing unit 4 at a predetermined sampling rate. For example, in the sampling circuit 11, the sampling frequency may be set in advance so that one symbol in the symbol data string transmitted by the baseband signal can be sampled a plurality of times. The A / D converter 12 converts the baseband signal sampled by the sampling circuit 11 into digital data. The digital data generated by the A / D converter 12 is stored in the frame memory 13. The frame memory 13 temporarily stores the digital data generated by the A / D converter 12 by, for example, a FIFO (First In First Out) method.

  The synchronization word storage unit 14 stores data indicating the code pattern of the synchronization word SW included in each frame of the control channel 110, the physical communication channel 111, and the direct communication channel 112 as shown in FIGS. , Stored in advance. The preword storage unit 15 includes a prefield PW used in the post field PF included in the frame of the control channel 110 shown in FIG. 2A and the preamble PA included in the frame of the direct communication channel 112 shown in FIG. Data indicating the code pattern is stored in advance.

  The synchronization calculation unit 16 establishes bit synchronization or frame synchronization based on the digital data stored in the frame memory 13 and the data stored in the synchronization word storage unit 14 or the data stored in the preword storage unit 15. The arithmetic processing for performing is performed. For example, the synchronization calculation unit 16 performs a correlation calculation based on the digital data stored in the frame memory 13 and the data stored in the synchronization word storage unit 14 or the data stored in the preword storage unit 15. It is determined whether or not the correlation value obtained as a result of the calculation exceeds a predetermined threshold value. And a predetermined | prescribed synchronous timing signal is output at the timing which exceeds a predetermined threshold value and a correlation value becomes maximum value. The synchronization timing signal output from the synchronization calculation unit 16 is used, for example, to process frame structure digital data in the baseband signal processing unit 1 or other digital signal processing circuits.

  The operation control unit 17 controls the operation of each part in the baseband signal processing unit 1 based on the communication state and the operation state in the mobile radio communication apparatus 101. For example, the operation control unit 17 sets the calculation process executed by the synchronization calculation unit 16 to establish synchronization as a calculation process using data stored in the synchronization word storage unit 14, or the synchronization word storage unit 14 and Switching between calculation processing using data stored in both of the preword storage units 15 is performed.

  As shown in FIG. 4, for example, the radio communication control apparatus 102 shown in FIG. 1 includes a control channel transmission unit 120, a plurality of communication channel transmission units 121-1 to 121-n (n is an integer of 2 or more), It has. The control channel transmission unit 120 transmits an RF signal for transmitting digital data to each mobile radio communication apparatus 101 using the control channel 110. Each communication channel transmission unit 121-1 to 121-n transmits an RF signal for transmitting digital data to each mobile radio communication apparatus 101 using the physical communication channel 111. A frame timing signal for synchronizing frames transmitted on the control channel 110 and the physical communication channel 111 is transmitted from the control channel transmission unit 120 to each of the communication channel transmission units 121-1 to 121-n. It is done. With this frame timing signal, the frame of the control channel 110 and the frame of the physical communication channel 111 are transmitted at the same timing as shown by the dotted lines in FIGS.

  Hereinafter, an operation in which mobile radio communication apparatus 101 acquires synchronization in mobile radio communication system 100 according to the embodiment of the present invention will be described. Here, the operation state (synchronization state) related to synchronization in the mobile radio communication apparatus 101 includes an initial synchronization state for establishing bit synchronization and frame synchronization, and a synchronization maintaining state for maintaining frame timing after synchronization is established. There are three operating states: a resynchronization state for establishing synchronization again after synchronization is lost. In each mobile radio communication apparatus 101, the operation control unit 17 included in the synchronization detection circuit 10 specifies an operation state related to synchronization according to a communication state or the like, and controls the operation of the synchronization calculation unit 16 according to the specified operation state. .

  More specifically, whether the operation control unit 17 acquires synchronization using only the synchronization word SW, or acquires synchronization using both the synchronization word SW and the preword PW, according to the specified synchronization state regarding synchronization. Judgment is made. FIG. 5 is a diagram illustrating a correspondence relationship between a radio channel to be received, an operation state related to synchronization in the mobile radio communication apparatus 101, a method for acquiring synchronization, and a synchronization condition for determining that synchronization is established. .

  As shown in FIG. 5, when the control channel 110 is a reception target, when the control channel 110 is in the initial synchronization state or the resynchronization state, synchronization acquisition is performed using both the preword PW and the synchronization word SW. At this time, the synchronization accuracy is improved because it is substantially equivalent to detecting the frame timing using a long code pattern as the synchronization word SW. Therefore, at this time, as a synchronization condition, it is determined that both the preword PW and the synchronization word SW can be detected once only when the calculation result in the synchronization calculation unit 16 exceeds a predetermined threshold value once, and synchronization is established. And it is sufficient. Note that the synchronization condition can be changed according to the specifications of the mobile radio communication system 100, and may be set so as to be surely reduced as compared with the conventional case.

  When the control channel 110 is a reception target and is in a synchronization maintaining state, acquisition of frame synchronization has already been completed on the mobile radio communication apparatus 101 side. Therefore, it is only necessary to confirm that the synchronization word SW of each frame has been received at a predetermined timing. Therefore, at this time, synchronization is acquired using only the synchronization word SW, and it is determined that the synchronization word SW can be detected only when the operation result exceeds the predetermined threshold value once as a synchronization condition. It may be maintained.

  When the physical communication channel 111 is a reception target, synchronization acquisition is performed using only the synchronization word SW regardless of the operation state related to synchronization. Here, in the frame of the physical communication channel 111, as shown in FIG. 2B, a portion including the preword PW is not arranged. On the other hand, as shown in FIG. 4, a frame timing signal is sent from the control channel transmission unit 120 to each of the communication channel transmission units 121-1 to 121-n. The frame of the communication channel 111 is transmitted at the same timing. Therefore, when the mobile wireless communication apparatus 101 shifts the reception target from the control channel 110 to the physical communication channel 111, if the physical communication channel 111 is received at the same frame timing as when the control channel 110 is received, Frame synchronization can be acquired.

  As a synchronization condition when the physical communication channel 111 is a reception target, the synchronization word SW is set only when the calculation result in the synchronization calculation unit 16 exceeds a predetermined threshold value once in the initial synchronization state or the synchronization maintenance state. What is necessary is just to determine with having detected and to have established the synchronization (or maintained). On the other hand, in the resynchronization state in which resynchronization is performed due to loss of synchronization, or at the time of subsequent entry at the time of group call, the synchronization accuracy may deteriorate. Therefore, at this time, as a synchronization condition, it is determined that the synchronization word SW has been detected a plurality of times (for example, twice) by continuously exceeding a predetermined threshold value a plurality of times (for example, twice), and synchronization is established. If you do. At the time of resynchronization or follow-up entry, the mobile radio communication apparatus 101 exists in an environment close to the limit at which a call using the physical communication channel 111 is established. For this reason, even if a slight delay occurs in the establishment of synchronization due to stricter synchronization conditions as compared with the initial synchronization state and the synchronization maintenance state as described above, it is unlikely to be a big problem.

  When the direct communication channel 112 is a reception target, a preamble PA including the preword PW is arranged only at the beginning of the frame at the start of transmission. Therefore, as a method for obtaining synchronization, both a method using only the synchronization word SW and a method using both the preword PW and the synchronization word SW can be used. Then, the synchronization condition may be selected according to the method used. Specifically, when both the pre-word PW and the synchronization word SW are used, both the pre-word PW and the synchronization word SW can be detected once only when the calculation result in the synchronization calculation unit 16 exceeds a predetermined threshold value once. It can be determined that synchronization has been established. On the other hand, when only the synchronization word SW is used, it is determined that the synchronization word SW can be detected a plurality of times (for example, twice) because the calculation result continuously exceeds a predetermined threshold value a plurality of times (for example, twice). Then, it is sufficient that synchronization is established.

Next, a specific example of calculation processing executed for establishing synchronization in the synchronization calculation unit 16 will be described. Here, the number of symbols of the synchronization word SW is n + 1, the data of the synchronization word SW is S0 to Sn, and the sampling data traced back to several symbols in the past from the reception point in the baseband signal demodulated by the mobile radio communication apparatus 101 is a. and ₀ ~a _n. In this case, the correlation value can be obtained by an operation such as Equation 1. Frame synchronization can be acquired based on the timing at which the correlation value becomes maximum.

  As a specific example, it is assumed that the synchronization words S0 to S3 are -3, +1, -3, and +3, respectively. Assume that the baseband signal demodulated by the mobile radio communication apparatus 101 has a waveform as shown in FIG. In the example shown in FIG. 6, it is assumed that sampling is performed once per symbol.

  In this case, the correlation values obtained at timings T4 to T11 are compared with a predetermined threshold value. Then, frame synchronization can be established based on the maximum point that is larger than the threshold value. In the example shown in FIG. 6, since the correlation value is “28” and maximum at timing T8, it is determined that it is the reception timing of the synchronization word SW, and frame synchronization can be established.

Further, the sampling data back to the past 20 symbols from the received point in the demodulated baseband signal at the mobile wireless communication device 101 and a ₀ ~a _19, the sync word SW stored in the sync word storage unit 14 S ₀ to S _9, the Purewado PW stored in Purewado storage unit 15 and _P 0 to P _9. The threshold value for synchronization determination is Th1 when only the synchronization word SW is used, and is Th2 when both the preword PW and the synchronization word SW are used. Here, the correlation value increases as the word length increases. Therefore, settings are made in advance such that Th1 <Th2.

When the synchronization is acquired using only the synchronization word SW, the synchronization calculation unit 16 performs the calculation using Equation 2 to obtain the sampling data a _{10 to} a ₁₉ and the data S _{0 to} S ₉ indicating the synchronization word SW. The correlation value C1 is specified.

For example, if the baseband signal as shown in FIG. 7 (A) by the reception processing unit 4 is demodulated, data sampled by the sampling circuit 11 in the period indicated by an arrow ar1 are sampling data a ₁₀ ~a ₁₉ Are sequentially stored in the frame memory 13. The synchronization word storage unit 14 stores in advance data S _{0 to} S ₉ indicating a code pattern corresponding to the waveform of the synchronization word SW as shown in FIG. 7B. The synchronization calculation unit 16 specifies a correlation value C1 between the sampling data a _{10 to} a ₁₉ stored in the frame memory 13 and the data S _{0 to} S ₉ indicating the synchronization word SW stored in the synchronization word storage unit 14. The calculation process is executed. Note that the period indicated by the arrow ar1 moves to the right (backward on the time axis) as time passes, as indicated by the arrow ar2 in FIG. 7A. The frame memory 13 stores the sampled data by the FIFO method.

  Thus, the correlation value C1 specified by the synchronization calculation unit 16 varies with the passage of time as shown in FIG. Then, at timing T21 when the correlation value C1 exceeds the threshold Th1, it is determined that the synchronization word SW has been received, so that frame synchronization can be established.

When the synchronization is acquired using both the pre-word PW and the synchronization word SW, the synchronization calculation unit 16 performs the calculation using Equation 2 so that the sampling data a _{10 to} a ₁₉ and the data S ₀ indicating the synchronization word SW are obtained. identifying a correlation value C1 between to S _9. Further, the synchronization calculating unit 16 executes a calculation using Equation 3, to identify a correlation value C2 between the data _P 0 to P ₉ indicating the sampling data _a 0 ~a ₉ and Purewado PW.

For example, if the baseband signal as shown in FIG. 8 (A) by the reception processing unit 4 is demodulated, data sampled by the sampling circuit 11 in the period indicated by an arrow ar3 are sampling data a ₀ ~a ₁₉ Are sequentially stored in the frame memory 13. Note that the period indicated by the arrow ar3 moves to the right (backward on the time axis) as time passes, as indicated by the arrow ar4 in FIG. 8A. The synchronization word storage unit 14 stores in advance data S _{0 to} S ₉ indicating code patterns corresponding to the waveform of the synchronization word SW as shown in FIG. 8B. The Purewado storage unit 15, the data P ₀ to P ₉ indicating the code pattern corresponding to Purewado PW having a waveform as shown in FIG. 8 (B), are stored in advance.

The synchronization calculation unit 16 calculates a correlation value C2 between the sampling data a _{0 to} a ₉ stored in the frame memory 13 and the data P _{0 to} P ₉ indicating the preword PW stored in the preword storage unit 15. Execute the process. At the same time, the synchronization calculation unit 16 obtains a correlation value C1 between the sampling data a _{10 to} a ₁₉ stored in the frame memory 13 and the data S _{0 to} S ₉ indicating the synchronization word SW stored in the synchronization word storage unit 14. An arithmetic process for specifying is executed. The correlation value C1 specified by the synchronization calculation unit 16 varies with time as shown in FIG. Further, the sum C1 + C2 of the correlation value C1 and the correlation value C2 also varies with the passage of time as shown in FIG. 8D. Then, by determining that the synchronization word SW is received at the timing T22 when the value of C1 + C2 exceeds the threshold Th2, frame synchronization can be established.

  When the control channel 110 is a reception target and the mobile radio communication apparatus 101 is in the initial synchronization state for establishing synchronization, only the process of acquiring synchronization using both the preword PW and the synchronization word SW is executed. That's fine. Therefore, as illustrated in FIGS. 8A to 8D, synchronization can be established by setting the maximum point where the sum of correlation values C1 + C2 exceeds the threshold Th2 as a synchronization point.

  Further, when the direct communication channel 112 is a reception target and the mobile radio communication apparatus 101 is in the initial synchronization state, a process of acquiring synchronization using both the preword PW and the synchronization word SW, and only the synchronization word SW are performed. Both processes that use and acquire synchronization must be considered. Even in this case, the synchronization point can be specified based on the comparison between the correlation value C1 and the threshold Th1, and the comparison between the correlation value sum C1 + C2 and the threshold Th2. By specifying the synchronization point by such a simple calculation, it is possible to suppress an increase in the processing amount in the arithmetic processing by the synchronous arithmetic unit 16. When the correlation value C1 exceeds the threshold value Th1 and reaches the maximum value, and the sum C1 + C2 of the correlation values exceeds the threshold value Th2 and reaches the maximum value, the synchronization is acquired using both the preword PW and the synchronization word SW. The synchronization condition is preferentially applied, and for example, it may be determined that the synchronization has been established only by exceeding the threshold value Th2.

  In some cases, the word length of the synchronization word is shortened by narrowing the bandwidth of the radio channel or supporting a large zone. In the present invention, even when the synchronization word is reduced to 20 bits per 80 msec, both the preword PW and the synchronization word SW are used appropriately or only the synchronization word SW is used depending on the operation state related to synchronization in the mobile radio communication apparatus 101. Use to get synchronization. As a result, even when the word length of the synchronization word is shortened, it is possible to detect synchronization with good accuracy. Further, by shortening the word length in the synchronization word, a communication link can be quickly established between the mobile radio communication apparatus 101 and the radio communication control apparatus 102 or between the plurality of mobile radio communication apparatuses 101. it can.

  In addition, when synchronization is established or maintained using only the synchronization word SW, the synchronization calculation unit 16 performs calculation processing for comparing the correlation value C1 with the threshold Th1, thereby reducing the amount of processing and consuming. Electric power can be suppressed. Further, the frame of the control channel 110 and the frame of the physical communication channel 111 are transmitted at the same timing, and the portion including the pre-word PW is not arranged in the frame of the physical communication channel 111. In addition, the preamble PA including the pre-word PW is arranged only at the start of transmission in the frame of the direct communication channel 112, and the preamble PA is not arranged in a frame transmitted after that. Thereby, in the physical communication channel 111 and the direct communication channel 112 that are easily restricted by the information transmission speed (capacity), the amount of data transmitted for control can be reduced, and the restriction by the information transmission speed can be relaxed. it can.

  Note that the synchronization calculation unit 16 is not limited to the one that executes the correlation calculation to establish the synchronization, and may be any one that can execute any calculation process and establish the synchronization. For example, the Euclidean distance between the predefined synchronization word and the demodulated baseband signal sampling data may be specified, and the difference between the specified distances may be squared and added by an amount corresponding to the synchronization word.

  The mobile radio communication system 100 is not limited to a large zone land mobile radio communication system, and may be a micro cell system. Furthermore, the modulation method is not limited to the four-value FSK modulation method, and any digital multi-value modulation method may be used. The communication system between the mobile radio communication apparatus 101 and the radio communication control apparatus 102 is not limited to the FDMA system, and the present invention can be applied to the TDMA system as it is.

DESCRIPTION OF SYMBOLS 1 Baseband signal processing part 2 Transmission processing part 3 Antenna 4 Reception processing part 5 Transmission / reception separation part 10 Synchronization detection circuit 11 Sampling circuit 12 A / D converter 13 Frame memory 14 Synchronization word storage part 15 Preword storage part 16 Synchronization calculation part 17 Operation control unit 100 Mobile radio communication system 101 Mobile radio communication apparatus 102 Radio communication control apparatus 110 Control channel 111 Physical communication channel 112 Direct communication channel 120 Control channel transmission unit 121-1 to 121-n Communication channel transmission unit PA Preamble PF Postfield PW Preword SW Sync word

Claims (4)

Demodulating means for receiving a radio signal transmitted on a predetermined radio channel and demodulating a baseband signal;
Frame synchronization means for detecting frame synchronization by detecting at least a predetermined synchronization word from the symbol sequence represented by the baseband signal demodulated by the demodulation means,
The frame synchronization means, when demodulating a baseband signal from a radio signal transmitted on a control channel provided from a base station among the radio channels by the demodulation means, has a predetermined code at the head of each frame. A synchronization word consisting of a pattern is placed, but the synchronization status is re-synchronized from the initial synchronization and the resynchronization from a plurality of frames where a post field containing a preword consisting of a code pattern different from the synchronization word is placed at the end of each frame Depending on whether the synchronization is maintained, the first detection operation for detecting only the synchronization word and the second detection operation for detecting both the synchronization word and the preword are performed.
The frame synchronization means further demodulates a baseband signal from a radio signal transmitted on a communication channel directly with another mobile station among the radio channels by the demodulation means, Preamble including a preword is arranged at the head of the frame, and depending on whether the synchronization state is initial synchronization, resynchronization or synchronization maintenance from a plurality of frames in which a synchronization word is arranged in each frame Performing either the first detection operation or the second detection operation;
A mobile radio communication apparatus characterized by the above. The frame synchronization means, when demodulating a baseband signal from a radio signal transmitted on the direct communication channel by the demodulation means, a synchronization word when the synchronization state is either initial synchronization or resynchronization Frame synchronization is acquired when a sync word can be detected multiple times, or when a sync word and pre-word can be detected once, or when the sync status is synchronized, the sync word can be detected once. Judge that it was done,
The mobile radio communication apparatus according to claim 1. A communication processing method by a mobile radio communication apparatus that performs radio communication with either a base station or another mobile station by transmitting / receiving a radio signal transmitted on a predetermined radio channel,
A demodulation step of receiving a radio signal and demodulating a baseband signal;
A frame synchronization step of acquiring frame synchronization by detecting at least a predetermined synchronization word from the symbol sequence represented by the baseband signal demodulated in the demodulation step;
The frame synchronization step includes:
When the baseband signal is demodulated from the radio signal transmitted on the control channel provided from the base station among the radio channels in the demodulation step, a synchronization word consisting of a predetermined code pattern is formed at the head of each frame. On the other hand, at the end of each frame, the synchronization status is either initial synchronization, resynchronization, or synchronization maintenance from a plurality of frames in which a post field including a preword having a code pattern different from the synchronization word is arranged. Depending on whether there is a first detection operation that detects only the synchronization word or a second detection operation that detects both the synchronization word and the preword,
When the baseband signal is demodulated from the radio signal transmitted directly on the communication channel with other mobile stations in the radio channel in the demodulation step, a preword is included at the beginning of the frame at the start of transmission. From the plurality of frames in which the preamble is arranged and the synchronization word is arranged in each frame, the first detection operation and the first detection operation are performed according to whether the synchronization state is initial synchronization, resynchronization, or synchronization maintenance. Perform one of the two detection operations,
A communication processing method. In the frame synchronization step, when the baseband signal is demodulated from the radio signal transmitted on the direct communication channel in the demodulation step, the synchronization state is either initial synchronization or resynchronization. Frame synchronization when the sync word can be detected multiple times, or when the sync word and pre-word can be detected once, or when the sync status is synchronized, the sync word can be detected once. It is determined that
The communication processing method according to claim 3.

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