JP4057445B2 - Wireless access system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, when switching radio frequencies between radio stations, switching information as information on timing and new radio frequency is transmitted and received over several frames, and radio channel down due to data loss in a radio section is prevented. The present invention relates to a wireless access system and a wireless device used therefor.
[0002]
[Prior art]
Subscriber radio access system that provides subscribers with high-speed lines using microwave radio for the purpose of complementary use of optical fiber networks and inter-island communication as the next generation ultra-high-speed information communication infrastructure is being developed There is a growing demand for (FWA: Fixed Wireless Access). Conventionally, as this wireless access system, the P-P (Point-Point) method by inter-building communication for enterprises and the P-MP for general houses and small offices (SOHO: Small Office Home Office) (Point-Multi Point) method is considered, but wireless node stations are arranged in a mesh and autonomously set the line capacity and route, thereby enabling high-speed, large-capacity and highly efficient mesh-type TDD radio. The access system is expected to be put into practical use in the future.
[0003]
Here, an outline of a configuration of the mesh type TDD wireless access system will be described with reference to FIG. FIG. 8 is a diagram illustrating an example of a schematic configuration of a mesh-type TDD wireless access system. As shown in FIG. 8, a plurality of wireless node stations 1 arranged in a mesh shape are connected by a wireless link 2. The wireless node station exchanges information with other wireless node stations and performs an operation adapted to the network information of the mesh type TDD wireless access system. If the wireless node station is a terminal station, information is exchanged with the user via a user terminal provided in the wireless node station. Further, the wireless node station has a relay function, and if necessary, relays between wireless node stations that are not directly connected to the wireless link. The radio node station performs radio transmission with one or a plurality of other radio node stations connected by a radio link. The wireless node station forms a mesh network by performing relaying.
For example, the following patent documents are known as subscriber wireless access (FWA) systems.
[0004]
[Patent Document 1]
JP 2001-169345 A (page 3-4, FIG. 3)
[0005]
[Problems to be solved by the invention]
However, in the conventional technology, for example, in transmission / reception between radio stations, when the transmitting radio station transmits radio frequency switching information, it is determined whether the receiving radio station (opposing radio station) has received the information. I can't. Even if the opposite radio station (node) is not normally receiving, the transmitting radio station that transmitted the switching information unilaterally switches the radio frequency, so that the receiving radio station normally receives the information. If not, the radio stations are out of synchronization and the radio channel is down.
In the above case, even if ACK (reception confirmation code) is transmitted as radio frequency switching information from the opposite radio station, it cannot be determined whether or not the transmitting radio station has successfully received the ACK. Further, even if the transmitting side radio station transmits the switching information continuously for several frames, there is a problem that the opposite radio station cannot determine how many frames later the radio frequency is to be switched.
[0006]
The present invention has been made in order to solve the above-described conventional problems, and avoids a failure of attribute switching due to data loss in a wireless section, and is therefore used for a wireless access system in which a wireless channel is unlikely to occur. The purpose is to provide a wireless device.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a wireless access system constructed with at least two wireless devices, and when the at least two wireless devices switch frequencies, the information regarding the switching is mutually transmitted and received to confirm. And a frequency switching means for switching the frequency according to the information related to the switching when the frequency switching confirmation means can mutually confirm the frequency switching.
[0008]
Also, in the radio access system of the present invention, the frequency switching confirmation means transmits / receives information about the switching timing and switching frequency as the switching information over several frames before frequency switching between the at least two radio devices. It is characterized by.
[0009]
Further, the radio device according to the present invention includes a frequency change factor detecting means (for example, an interference wave level detector 111) for detecting a factor for switching a radio frequency, and at least a radio frequency switching when the frequency change factor is detected. From frequency switching information transmitting means (for example, control data generating unit 108, transmitting unit 103, step S1) for transmitting frequency switching information including timing, and a partner radio device for the frequency switching information transmitted by the frequency switching information transmitting unit When receiving a response from the counterpart radio by the response receiving means (for example, receiving section 104, control data receiving section 109, step S2) and receiving the response, the radio frequency is set according to the frequency switching information. Frequency switching means (control data generator 108, radio frequency switching signal generator 105, switch -Up S3) and is intended to be equipped with.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a radio node station (radio device) in a TDD radio access system according to an embodiment of the present invention, and FIG. 2 is a diagram showing a radio frame configuration in the embodiment of the present invention. Here, for the sake of explanation, the illustrated radio node station (first radio node station) 100 and radio node station (second radio node station) 200 will be described as an example.
[0011]
As shown in FIG. 1, a radio node station 100 (200) passes an antenna 101 (201) that transmits and receives radio frequency modulated waves, a frequency converter 102 that performs frequency conversion, and transmission data to the frequency converter 102. A transmission unit 103; a reception unit 104 that receives reception data from the frequency converter 102; a radio frequency switching signal generator 105 that issues a frequency switching instruction to the frequency converter 102; a user data generation unit 106 that generates user data; A user data receiving unit 107 that receives user data, a control data generating unit 108 that generates control data, a control data receiving unit 109 that receives control data, a frame synchronization unit 110 that performs frame synchronization, and an interference wave level An interference wave level detector 111 for detection is provided. The wireless node station 200 having the antenna 201 can also have the same configuration as the wireless node station 100.
[0012]
In the above configuration, the frequency converter 102 converts a baseband modulated wave transmitted by the antenna 101 into a radio frequency modulated wave, or converts a radio frequency modulated wave received by the antenna 101 into a baseband frequency. Transmitting section 103, and outputs the respective data input from the user data generating unit 106 and the control data generating unit 108 in the radio frame configuration in the frequency converter 102. The receiving unit 104 receives the radio frame data input from the frequency converter 102 and outputs it to the user data receiving unit 107 and the control data receiving unit 109.
[0013]
The radio frequency switching signal generator 105 outputs to the frequency converter 102 a switching signal for instructing the radio frequency input from the control data generation unit 108 to the frequency converter 102 at the input timing. The user data generation unit 106 is connected to the user terminal 120 or the like, and outputs user data input from the user to the transmission unit 103 at a timing input from the frame synchronization unit 110. The user data receiving unit 107 is connected to the user terminal 120 or the like, receives user data from the receiving unit 104 at a timing input from the frame synchronization unit 110, and outputs the user data to the user terminal 120. The control data generation unit 108 performs operation 1 described later when a radio frequency switching request has already been issued from the own radio station at the timing input from the frame synchronization unit 110, and performs operation 2 otherwise.
[0014]
Here, in operation 1, the reception control data input from the control data receiving unit 109 is confirmed. When the switching request flag is “1”, control data for responding to the switching request is output to the transmitting unit 103. Further, when the switching count value in the control data is “1”, the radio frequency from the next radio frame is output to the radio frequency switching signal generator 105. When the switching request flag is “0”, the interference wave level input from the interference wave level detector 111 is compared with the interference wave level threshold value stored in the control data generation unit 108, and the interference wave level is determined. Is higher than the interference wave level threshold value, control data for requesting switching to the opposite radio station is output to the transmitter 103. The new radio frame frequency specifies a radio frequency other than the currently used radio frequency. Then, operation 2 is performed from the next radio frame.
[0015]
In operation 2, the switching count value in the control data in the previous radio frame is updated to a value obtained by subtracting 1 and the control data is output to the transmission unit 103. When the switching count value is 1, the new radio frequency is output to the radio frequency switching signal generator 105 so that the radio frame frequency is switched to the new radio frequency at the next radio frame timing. Operation 1 is performed from the next radio frame.
[0016]
The control data receiving unit 109 receives the control data input from the frequency converter 102 at the timing input from the frame synchronization unit 110. And the control data of a radio | wireless frame are output to a transmission part. As shown in FIG. 2, the one-way transmission data includes a control data part and a user data part. The control data part includes a synchronization fixed pattern CCH1, a switching request flag CCH2, a new data frame. A radio frequency number CCH3 and a switching count value CCH4 are included.
[0017]
The synchronization fixed pattern CCH1 is a frame synchronization fixed pattern used in the frame synchronization unit. The switch request flag CCH2 indicates that it is not a radio frequency switch request at “0”, indicates a radio frequency switch request at “1”, indicates a radio frequency switch response (ACK) at “2”, and switches to radio frequency at “3”. Represents a response (NAC). The new radio frequency number CCH3 represents the switching radio frequency identification number N (integer). The switching count value CCH4 represents the number of frames for switching the radio frequency (L to M (an integer of L, M> 0)).
[0018]
The frame synchronization unit 110 detects the synchronization fixed pattern CCH1 in the reception data input from the reception unit 104, and processes the user data generation unit 106, the user data reception unit 107, the control data generation unit 108, and the control data reception unit 109. Output start timing. The interference level detector 111 detects the interference wave level from the reception data input from the reception unit 104 and outputs the interference wave level to the control data generation unit 108.
[0019]
Hereinafter, the operation of the embodiment will be described with reference to FIGS. 3 is a flowchart showing the operation of the radio node station 100 that transmits a frequency switching request, FIG. 4 is a flowchart showing the operation of the radio node station 200 that receives the frequency switching request, and FIG. FIG. 6 shows a sequence when the wireless node station 200 has not successfully received the predetermined (m, m + 2) control data of the wireless frame from the wireless node station 100. FIG. FIG. 4 is a diagram showing a sequence in a case where a frequency switching request by a radio frame from the radio node station 100 cannot be normally received.
[0020]
First, the operation of the radio node station 100 shown in FIG. 3 will be described. In the radio frequency switching process, the radio node station 100 first transmits a radio frequency switch request (with interference) to the radio node station 200 that is the opposite node, and locks the node when the transmission is determined (step S1). ). Next, it is determined whether or not the response (request acceptance) in step S1 has been received from the wireless node station 200 (step S2). If received (step S2, Y), the counter frequency is notified to the opposite node and the radio frequency is received. The change is made (step S3), and then the lock is released (step S4). On the other hand, if it is determined in step S2 that no signal has been received (step S5, N), it is determined that no signal has been received for a certain period (for example, five frames) (step S5, Y), and then the process proceeds to step S4. End the process.
[0021]
Next, the operation of the radio node station 200 shown in FIG. 4 will be described. In the process when the radio node station 200 receives the radio frequency switching request, first, it is determined whether or not the node is locked (step S11). If the node is not locked (step S11, Y), A radio frequency switching response (ACK) is transmitted to the opposite node (radio node station 100), and the node is locked when ACK transmission is determined (step S12). Next, it is determined whether or not a countdown notification is received from the opposite node (wireless node station 100) (step S13). If received, the radio frequency is changed according to the countdown notification from the opposite node (step S14). Thereafter, the lock is released (step S15).
[0022]
On the other hand, if it is determined in step S13 that no signal has been received (step S13, N), it is determined that no signal has been received for a certain period (for example, 5 frames) (step S13, Y), and then the process proceeds to step S15. The process is terminated.
If it is determined in step S11 that the node is locked (step S11, N), the process proceeds to step S17, a radio frequency switching response (NAK) is transmitted to the opposite node, and the process ends.
[0023]
The countdown notification process in the radio node station 100 and the radio frequency switching process in the radio node station 200 for the above will be described with reference to FIG.
(Radio frame m)
First, in the radio frame m, when the radio node station 100 detects, for example, a high interference wave level while transmitting a radio frame, radio frequency switching request control data is transmitted. Next, (2) the radio node station 200 receives the control data (in this radio frame, it is understood that the radio node station 200 must switch the new radio frequency number to “1” after 3 frames). Then, the switching request flag of the reception control data is changed to “2”, and control data for radio frequency switching response is transmitted. The radio node station 100 receives the radio frequency switching response data from the radio node station 200.
[0024]
(Radio frame m + 1)
In the radio frame m + 1, (1) the radio node station 100 transmits control data obtained by decrementing only the switching count value in the radio frequency switching request control data transmitted in the radio frame m. (2) The radio node station 200 receives the control data transmitted by the radio node station 100, changes the switching request flag of the reception control data to “2”, and transmits control data for radio frequency switching response. (3) The radio node station 100 receives the radio frequency switching response control data from the radio node station 200.
[0025]
(Radio frame m + 2)
In the wireless frame m + 2, processes (1) to (3) are performed as in the case of the wireless frame m + 1.
[0026]
(Radio frame m + 3)
In the wireless frame m + 2, (1) since the switching count value of the wireless frame m + 2 is 1, the communication is performed by switching from the current wireless frame to the wireless frame frequency of the wireless frequency number “1”. (2) When the switching is completed, the control data switching request flag of the wireless node station 100 is set to “0” and the control data is transmitted. (3) The wireless node station 200 determines that the switching request flag of the reception control data switching request flag is “0”, and transmits the same control data as the reception control data to the wireless node station 100.
[0027]
Next, a sequence in the case where the wireless node station 200 has not successfully received the predetermined (m, m + 2) control data of the wireless frame from the wireless node station 100 will be described with reference to FIG.
In this sequence, since the radio node station 200 has successfully received the new radio frequency number and the switching count value in the radio frame m + 1, the radio node station 200 can switch to the new radio frequency in the radio frame m + 3. is there.
In the wireless node station 100, the switching request flag in the reception control data of the wireless frames m and m + 2 is not “2” indicating a response, but the switching request flag in the reception control data of the wireless frame m + 1 indicates a response “ Therefore, it is determined that the radio node station 200 has successfully received the transmission control data from the radio node station 100 in the radio frame m + 1, and the radio frame m + 3 switches to the new radio frequency.
[0028]
Next, a sequence in a case where the radio node station 200 cannot normally receive a frequency switching request from the radio node station 100 using a radio frame will be described with reference to FIG.
In this case, the wireless node station 200 never transmits the switching response control data to the wireless node station 100. Therefore, since the wireless node station 100 has never received the switching response control data, the wireless node station 100 continues to use the wireless frequency number “0” without switching to the wireless frequency number “1” from the wireless frame m + 3.
[0029]
【The invention's effect】
As described above, according to the present invention, it is possible to avoid a failure of attribute switching due to data loss in a wireless section, and to obtain a wireless access system and a wireless device used therefor in which wireless channel down is unlikely to occur. There is an effect.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a radio node station (radio device) in a TDD radio access system according to an embodiment of the present invention.
FIG. 2 is a diagram showing a radio frame configuration according to the embodiment of the present invention.
FIG. 3 is a flowchart showing an operation of a radio node station that transmits a frequency switching request.
FIG. 4 is a flowchart showing an operation of a radio node station that receives a frequency switching request.
FIG. 5 is a sequence diagram when a switching request is normally received.
FIG. 6 is a sequence in a case where a wireless node station that receives a frequency switching request cannot normally receive predetermined (m, m + 2) control data of a wireless frame from a wireless node station that transmits a frequency switching request. FIG.
FIG. 7 is a sequence diagram in a case where a wireless node station that should receive a frequency switching request cannot normally receive a frequency switching request using a radio frame.
FIG. 8 is a diagram illustrating an example of a schematic configuration of a mesh-type TDD wireless access system.
[Explanation of symbols]
100, 200 Radio node station, 101, 102 Antenna, 102 Frequency converter, 103 Transmitter, 104 Receiver, 105 Radio frequency switching signal generator, 106 User data generator 107 User data receiver, 108 Control data generator, 110 frame synchronization unit, 111 interference wave level detector, 120 user terminal.

Claims (3)

In a radio access system constructed by at least two opposing first and second opposing radios that transmit and receive at the same radio frequency a radio frame having a control data part and a user data part for transmission and reception respectively,
It said first and second opposing radio, each have the same configuration,
The first opposed radio device stores a radio frequency switching request in the switching request flag over a plurality of frames, stores a frequency other than the currently used radio frequency in the new radio frequency number, and wirelesss in the switching count value. Stores the value corresponding to the timing for switching the frequency and sends it to the second oncoming radio,
Second opposing radio, upon receiving a frame radio frequency switching request to the switching request flag is set, the switching request flag to store the radio frequency switching response, new radio frequency number the Xin received the Stores the frequency corresponding to the radio frequency number, stores the received switching count value in the switching count value, and transmits the switching count value to the first opposing radio device,
When receiving at least one frame in which a radio frequency switching response is set in the switching request flag, the first opposing radio device determines that the frequency switching has been mutually confirmed, and at the timing based on the switching count value, A radio access system that switches to a frequency set in a radio frequency number. The radio access system according to claim 1,
The switching count value is the number of radio frames until frequency switching,
The radio access system according to claim 1, wherein when the first and second opposing radio devices receive control data having the switching count value of 1, the radio frequency is switched to the new radio frequency at a next radio frame timing. The wireless access system according to claim 2, wherein the first and second opposing wireless devices are:
A frequency change factor detecting means for detecting an interference wave that causes the radio frequency to be switched;
Frequency switching information transmitting means for transmitting frequency switching information including at least radio frequency switching timing when the interference wave is detected;
Response receiving means for receiving a response from the counterpart wireless device to the frequency switching information transmitted by the frequency switching information transmitting means ;
A radio access system comprising: frequency switching means for switching a radio frequency according to the frequency switching information when a response is received from the counterpart radio by the response receiving means.

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