JPH0767179A - Radio communication system - Google Patents

Abstract

PURPOSE:To obtain the same communication quality with the use of plural radio links by one radio link by assigning plural carriers to one radio link and switching the carriers on the basis of the output of a differentiating process part by a TDMA-TDD system moving body communication system. CONSTITUTION:A control part 15 selects a slot for expanding a radio link a communication channel processor 13 and assigns plural predetermined carriers to one slot. Then a differential value obtained by the differentiating process part 17 is monitored to decide a threshold value. When the differential value is minus and its absolute value is larger than the threshold value, the generation of phasing is judged. In this case, when it is judged that a sufficient time is elapsed after last carrier switching as a result of time decision making, a mobile equipment is informed of the carrier switching with a communication signal and a timer is reset. The mobile equipment switches carriers from a next frame where the carrier switching report is received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to TDMA-TDD (T
ime Division Multiple Acces -Time Division
The present invention relates to a wireless communication device in a Duplex) type mobile communication system.

[0002]

2. Description of the Related Art In recent years, the spread of mobile communication has been remarkable. In order to meet the increasing demand, development of a digital mobile communication system in place of the conventional analog system has been actively promoted, and a TDMA-TDD mobile communication system is becoming a reality. In order to improve the wireless communication quality, which is the greatest bottleneck of wireless communication, in a TDMA-TDD mobile communication system, a plurality of wireless links are used for one communication line by using a plurality of slots in the same frame. Wireless communication devices are under consideration. Hereinafter, a conventional wireless communication device will be described with reference to the drawings.

First, the configuration of the mobile communication system will be described with reference to FIG. Reference numeral 91 is a wireless line control device for performing exchange control between a general public network or another mobile communication system and an in-system wireless line, mobile management of mobile units, and wireless management of the system. Reference numerals 92, 93, 94, and 95 are wireless connection devices for setting / releasing a wireless line with a mobile device under the control of the wireless line control device 91 and monitoring a wireless channel, and wireless zones A, B, respectively.
Form C and D. 96, 97, 98, 99, 100 are wireless connection devices 92, 93, 9 while moving in the system.
4 and 95 and the wireless line control device 91 are mobile devices that communicate with each other.

Next, the configuration of a conventional wireless connection device in the mobile communication system will be described with reference to FIG. Reference numeral 101 is an antenna unit for transmitting and receiving radio signals to and from a mobile device (not shown), and 102 is an antenna unit 101.
A radio unit 103 for converting a radio signal transmitted / received by a TDMA signal input / output from a communication channel processing unit and a control channel processing unit, which will be described later, 103 is a TDMA, respectively.
A plurality of communication channel processing units for converting communication signals and TDMA communication signals corresponding to slots, 104 a control channel processing unit for converting control signals and TDMA control signals, and 105 a communication channel processing unit 103 and control. A control unit that controls the channel processing unit 104 to control the entire connection device, a channel monitor unit 106 that measures a received signal level according to an instruction from the control unit 105, and a 107 inputs a communication signal to the communication channel control unit 103. In addition, a signal selection unit that selects an optimum signal from the communication signals output from the communication channel control unit 103, and an interface unit 108 that interfaces between the wireless line control device 1 (see FIG. 9) and the wireless connection device.

The operation of the conventional wireless connection device configured as described above will be described below. Prior to explanation, an example of the signal type of the wireless signal is shown in FIG. Figure 11
The number of slots is set to 6, but the following explanation is
It does not depend on the signal type. When a plurality of wireless links are set up by using a plurality of slots in the same frame for one communication line, the control unit 105
A slot for establishing a wireless link is selected from the communication channel processing unit 103, and a carrier is assigned to each selected slot according to a predetermined rule. Here, the communication channel processing unit 103 corresponds to the slots shown in FIG. 11 and performs transmission / reception with respect to each slot. When the number of slots is 6, six communication channel processing units 103 are required. . Here, a case will be described where two communication channel processing units 103 (1) and (2) are used to establish two wireless links to one mobile device. The communication signal from the wireless line control device 1 is input to the signal selection unit 107 via the interface unit 108. The signal selection unit 107 receives a communication signal from the two communication channel processing units 103 (1) and 103 (1) according to an instruction from the control unit 105.
Input in (2). Communication channel processing unit 103 (1),
In (2), each communication signal input from the signal selection unit 107 is framed and output to the wireless unit 102 as a TDMA communication signal. Communication channel processing unit 103
Since (1) and (2) respectively correspond to different slots, the same communication signal will be transmitted in a plurality of downlink slots. The plurality of slot carriers to be used are notified from the wireless connection device to the mobile device by a control signal prior to establishment of the communication channel. Radio section 102 generates a radio signal from the TDMA communication signal input from communication channel processing sections 103 (1) and (2), and transmits the radio signal from antenna section 101.

Next, the receiving operation in the wireless connection device will be described. The radio signal transmitted from the mobile device in the uplink slot corresponding to the slot used at the time of transmission is received by the antenna unit 101 and enters the radio unit 102. The radio unit 102 demodulates the radio signal and obtains a plurality of Ts.
Two communication channel processing units 1 corresponding to DMA communication signals
03 (1), output to (2). Communication channel processing unit 1
03 (1), (2) decomposes the TDMA communication signal,
The communication signal is output to the signal selection unit 107. At this time, the communication channel processing units 103 (1) and (2) input the presence / absence of a received signal error to the signal selection unit 107. Signal selector 1
07 selects a highly reliable communication signal from the communication signals from the communication channel processing units 103 (1) and (2) based on this received signal error information, and the interface unit 108
To the wireless line control device via.

In this way, a plurality of wireless links can be set up in one communication line. Note that the wireless communication in the mobile device has the same configuration and operation as the wireless connection device, except that the used slot carrier cannot be determined, and the description thereof is omitted here. Also, when the connection device communicates with a plurality of mobile devices, the above operation is performed independently for each mobile device.

[0008]

However, in the above-mentioned conventional wireless communication device, since a plurality of wireless links are used for one communication line, the use efficiency of the wireless line is inferior.
There is a problem that the wireless line is likely to be busy during high traffic. In addition, there is a problem that the hardware of the mobile device becomes complicated because the mobile device also needs to transmit and receive a plurality of links.

It is an object of the present invention to solve the above problems and to provide a wireless communication device capable of realizing communication quality equivalent to that when a plurality of wireless links are used by one wireless link.

[0010]

In order to achieve the above object, the present invention provides a wireless connection device with a differential processing section capable of calculating a differential value from a monitored reception level, and a wireless link device for one wireless link. And a control unit that switches the plurality of carriers based on the output of the differentiation processing unit.

According to the present invention, the wireless connection device is further provided with a correlation calculator for performing a correlation calculation of reception levels of a plurality of slots,
The control unit allocates different carriers to a plurality of slots, and determines the intervals of the carriers allocated to the plurality of slots based on the output of the correlation calculation unit.

[0012]

With the above structure, the present invention allocates a plurality of carriers to one slot, detects the occurrence of fading based on the reception level differential value obtained by the differential processing section,
By switching carriers, it is possible to realize communication quality equivalent to that when a plurality of wireless links are used by one wireless link.

Further, according to the present invention, a plurality of carriers assigned to one slot can be updated as necessary by performing a correlation calculation of reception levels of a plurality of slots.

[0014]

(Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings. The system configuration is the same as the conventional one shown in FIG. FIG. 1 is a block diagram showing the configuration of a first embodiment of a wireless connection device according to the present invention. In FIG. 1, reference numeral 11 denotes an antenna section for transmitting / receiving a radio signal to / from a mobile device (not shown), 12 denotes a radio signal transmitted / received by the antenna section 11 and a communication channel processing section and a control channel processing section described later. A radio unit for converting input / output TDMA signals,
Reference numeral 13 is a plurality of communication channel processing units for converting communication signals and TDMA communication signals respectively corresponding to TDMA slots, 14 is a control channel processing unit for converting control signals and TDMA control signals, and 15 is communication channel processing. A control unit that controls the unit 13 and the control channel processing unit 14 to control the entire connection device, a channel monitor unit 16 that measures a received signal level according to an instruction from the control unit 15,
Reference numeral 17 denotes a differential processing unit that calculates a differential value from the received signal level measured by the channel monitor unit 16, and reference numeral 18 denotes an interface unit that interfaces between the wireless line control device 1 (see FIG. 9) and the wireless connection device.

The operation of the wireless connection device configured as described above will be described below. The control unit 15 selects a slot forming a wireless link from the communication channel processing unit 13 and allocates a plurality of predetermined carriers to one slot. In the following, in the case of allocating two carriers, two communication channel processing units 13
The case of using (1) and (2) will be described. The communication signal from the wireless line control device 1 passes through the interface unit 18 and the communication channel processing units 13 (1) and (2).
Is input to the wireless unit 12 after being framed and turned into a TDMA communication signal. The wireless unit 12 converts the input TDMA communication signal into a wireless signal and transmits the wireless signal from the antenna unit 11. At this time, the used slot carrier is notified from the wireless connection device to the mobile device by a control signal prior to establishment of the communication channel.

Next, the receiving operation in the wireless connection device will be described. The radio signal transmitted from the mobile device in the uplink slot corresponding to the slot used at the time of transmission is received by the antenna unit 11 and enters the radio unit 12. The radio unit 12 demodulates the radio signal and outputs the obtained TDMA communication signal to the corresponding communication channel processing unit 13 (1) or (2). The communication channel processing units 13 (1) and (2) decompose the TDMA communication signal and transmit the communication signal to the radio network controller 1 via the interface unit 18. The control unit 15 measures the reception level with the channel monitor unit 16 when receiving a radio signal from a mobile device, and
The differential processing unit 17 obtains the differential value of the reception level. The control unit 15 detects the occurrence of fading from the obtained differential value and switches the carrier.

Next, a carrier switching method will be described with reference to the flow chart of FIG. The control unit 15 monitors the differential value obtained by the differential processing unit 17 (step 2
1) The threshold value is determined (step 22). If the reception level differential value is a negative value and its absolute value is greater than or equal to the threshold value, it is determined that fading has occurred. If it is determined that fading has not occurred, the process ends. If it is determined that fading has occurred, it is determined whether the timer value has passed a preset time (step 23). This timer represents the elapsed time from the previous switching, and is used to prevent the communication quality from deteriorating due to excessive carrier switching. As a result of the timer determination, when it is determined that a sufficient time has passed since the previous carrier switching, the mobile device is notified of the carrier switching on the communication signal (step 24) and the timer is reset (step 25). . The mobile device switches the carrier from the next frame after receiving the carrier switching notification. Then, when transmitting in the next frame, the carrier is switched. As a result, it is possible to switch carriers before the reception level is lowered due to fading, and it is possible to achieve communication quality equivalent to that when a plurality of wireless links are used by one wireless link. In the flow chart of FIG. 2, the carrier is switched by performing the differential value determination once, but the carrier may be switched based on the differential value determination result in consecutive frames.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The system configuration is the same as the conventional one shown in FIG. Figure 3
FIG. 6 is a block diagram showing the configuration of a second embodiment of the connection device in the present invention. Reference numeral 31 denotes an antenna section for transmitting / receiving radio signals to / from a mobile device (not shown), and 32 denotes radio signals transmitted / received by the antenna section 31 and input / output from a communication channel processing section and a control channel processing section described later. TD
A radio unit for converting the MA signal, and 33 are TDs, respectively.
A communication channel processing unit for converting a communication signal into a TDMA communication signal corresponding to the MA slot, 34 a control channel processing unit for converting a control signal into a TDMA control signal, and 35 a communication channel processing unit 33 and a control channel. A control unit that controls the processing unit 34 and controls the entire connected device, 36 is a channel monitor unit that measures the received signal level in accordance with an instruction from the control unit 35, and 37 is a unit that measures the received signal level from the received signal level measured by the channel monitor unit 36. A differential processing unit for calculating a differential value, 38 a correlation operation unit for performing a correlation operation between the reception levels of a plurality of slots measured by the channel monitor unit 36, and 39 a wireless line control device (not shown) and a connection device. It is an interface part that takes an interface.

The operation of the wireless connection device configured as described above will be described below. The present embodiment is different from the first embodiment in that a plurality of carriers assigned to one slot are not fixedly provided but are updated as needed. This method will be described later. The control unit 35 can select a slot for establishing a wireless link from the communication channel processing unit 33 and allocate a plurality of carriers to one slot. In the present embodiment, unlike the first embodiment, a plurality of slots can be assigned to one communication line. Regarding the used slot carrier, the carrier can be selected by the carrier determined by the control unit 35. Hereinafter, a case where two carriers are assigned to one communication line will be described. The communication signal from the wireless line control device 1 is input to the communication channel processing unit 33 via the interface unit 39, is framed, becomes a TDMA communication signal, and is input to the wireless unit 32. The wireless unit 32 converts the input TDMA communication signal into a wireless signal and transmits the wireless signal from the antenna unit 31. At this time, the used slot carrier is notified from the wireless connection device to the mobile device by a control signal prior to establishment of the communication channel.

Next, the receiving operation in the wireless connection device will be described. The radio signal transmitted from the mobile device in the uplink slot corresponding to the slot used at the time of transmission is received by the antenna unit 31 and enters the radio unit 12. The radio unit 12 demodulates the radio signal and outputs the obtained TDMA communication signal to the corresponding communication channel processing unit 33. The communication channel processing unit 33 decomposes the TDMA communication signal,
The communication signal is transmitted to the wireless line control device 1 via the interface unit 39. When receiving a radio signal from a mobile device, the control unit 35 measures the reception level with the channel monitor unit 36, and obtains the differential value of the reception level with the differentiation processing unit 37. The control unit 35 detects the occurrence of fading from the differential value and switches the carrier. The carrier switching method is the same as that shown in FIG. 2, and the description is omitted here.

Next, a method of selecting a plurality of carriers will be described. In mobile communication, the biggest cause of deterioration of wireless communication quality is frequency selective fading associated with multipath. An example of frequency selective fading is shown in FIG. This is a received signal spectrum when a wideband signal is transmitted, and the specific frequency levels indicated by reference numerals 41 and 42 are attenuated. This is why it is called frequency selective fading. Therefore, by assigning a set of carriers that are not attenuated at the same time to one slot, it is possible to more effectively improve the wireless communication quality. Since the interval of frequencies that are attenuated at the same time depends on the usage environment
It is necessary to select and update as needed. For example,
If no improvement in communication quality is observed due to the carrier switching described above, a plurality of carriers are selected. Since the carrier combination is considered to depend on the carrier interval, this carrier interval is obtained. When selecting a plurality of carriers, a plurality of slots are assigned to one communication channel, and different carriers are assigned to the next slot. Here, for simplification of description, two slots are allocated to one communication signal, carriers apart from each other by a fixed carrier are allocated, correlation calculation of the reception level of each slot in the connection device is performed, and the correlation value is calculated. Based on this, it is determined whether the carrier interval is appropriate. The reception level measured by the channel monitor unit 36 is input to the correlation calculation unit 38, and the correlation calculation unit 38 calculates the correlation value under the control of the control unit 35. Make a choice.

Next, a specific method of carrier selection will be described with reference to FIG. First, when selecting a carrier, the carrier interval is initialized (step 5).
1). This value uses the previously determined carrier interval. Next, a set of carriers separated by the carrier interval is assigned to two slots, and correlation calculation between reception levels of the carriers is performed (step 52). The correlation calculation will be described later. Next, the threshold value of the correlation value obtained by the correlation calculation is determined. In step 53, as a correlation value determination, it is determined whether or not the carrier interval at that time is appropriate. If it is determined to be appropriate, the carrier selection is ended. When it is determined that it is not appropriate, the correlation value determination in step 54 is performed. In step 54, a judgment is made based on a threshold that is weaker than that in step 53, and it is judged how far the correlation value is from the target value. If the correlation value is slightly different from the target value by the correlation value determination, carrier shift 1 is executed (step 5
5) If not, carry out carrier shift 2 (step 56). The difference between carrier shift 1 and carrier shift 2 is that carrier shift 1 shifts the carrier interval by one carrier, whereas carrier shift 2 is M.
The carrier interval is shifted by carrier. The value of M is, for example, about one third of the carrier interval selected at the time of previous carrier selection. By changing the shift width of the carrier interval according to the correlation value, the carrier interval is efficiently selected.

Next, the correlation calculation will be described with reference to FIG. First, the reception levels of two carriers are measured (step 61), and it is determined whether or not the reception levels of each carrier all exceed a preset threshold value (step 62). If all the reception levels exceed the threshold value, the process returns to the measurement of the reception level. If either one of the carriers is below the threshold value, the level difference between the carriers is calculated (step 63) and the counter is incremented (step 64). This operation is continued until the counter value becomes N (step 65). After the level difference is calculated N times, the average value is calculated and used as the correlation value (step 66).

Next, the carrier shift 1 will be described with reference to FIG. In carrier shift 1, a correlation calculation is performed for a carrier on the high frequency side of one carrier and a carrier on the low frequency side of one carrier with respect to the initially set carrier interval, and both are compared, and carrier search is performed on either the high frequency side or the low frequency side. Make a carrier shift to decide whether to proceed to. In the carrier shift 1, first, it is determined whether or not the comparison of the correlation values is completed (step 71). If the comparison is completed, if it is shifted to the high frequency side (step 72), one carrier is increased (step 71). 73), if not shifted to the high frequency side, one carrier is down (step 74). If the correlation value comparison is not completed and the high frequency side shift is not completed (step 75), the carrier is increased by one carrier to the high frequency side (step 76), and the process is completed. If the high frequency side shift is completed, it is determined whether the low frequency side shift is completed (step 77),
If the shift on the low frequency side has also been completed, the correlation values on the high frequency side and the low frequency side are compared (step 78) to determine in which direction the carrier should be shifted. If the shift to the low frequency side has not been completed, two carriers are moved down to the low frequency side (step 79).

Next, regarding the processing of carrier shift 2,
The carrier shift 2 is the same as the carrier shift 1 except that the carrier shift width is M carriers as described above. Therefore, only the flow chart is shown in FIG. 8 and the description thereof is omitted.

As described above, a carrier set effective for frequency selective fading can be selected, and more reliable wireless communication can be performed by using one slot.

[0027]

As described above, according to the present invention, the wireless connection device is provided with the differential processing unit capable of calculating the differential value from the reception level, and the carrier is switched based on the differential value, whereby one wireless connection is obtained. The link enables communication quality equivalent to that when a plurality of wireless links are used.

Further, according to the present invention, a plurality of carriers assigned to one slot can be updated as necessary by providing a correlation calculation unit for performing a correlation calculation of reception levels of a plurality of slots.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wireless connection device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a carrier switching process in the first embodiment.

FIG. 3 is a block diagram showing a configuration of a wireless connection device according to a second embodiment of the present invention.

FIG. 4 is a signal waveform diagram for explaining frequency selective fading in the second embodiment.

FIG. 5 is a flowchart showing carrier selection processing in the second embodiment.

FIG. 6 is a flowchart showing a carrier correlation calculation process in the second embodiment.

FIG. 7 is a flowchart showing a process of carrier shift 1 in the second embodiment.

FIG. 8 is a flowchart showing a process of carrier shift 2 in the second embodiment.

FIG. 9 is a block diagram showing the configuration of a mobile communication system.

FIG. 10 is a block diagram showing a configuration of a conventional wireless connection device.

FIG. 11 is a schematic diagram showing a frame configuration in a mobile communication system.

[Explanation of symbols]

 11, 31 Antenna section 12, 32 Radio section 13, 33 Communication channel processing section 14, 34 Control channel processing section 15, 35 Control section 16, 36 Channel monitoring section 17, 37 Differentiation processing section 18, 39 Interface section 38 Correlation calculation section

Claims (2)

[Claims] 1. In a TDMA-TDD mobile communication system, a differential processing unit for calculating a differential value of a reception level to a wireless connection device, a plurality of carriers are assigned to one wireless link, and an output of the differential processing unit. And a control unit for switching the plurality of carriers based on the above. 2. A wireless connection device is provided with a correlation calculation unit for performing a correlation calculation of reception levels of a plurality of slots, a control unit assigns different carriers to the plurality of slots, and based on an output of the correlation calculation unit, The wireless communication apparatus according to claim 1, wherein an interval between carriers assigned to a plurality of slots is determined.