JP2007006078A - Radio communication system and radio communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method setting the measuring timing of the disturbance waves of a control channel at random and being capable of detecting the interference of the control channel, even under all environments in a digital radio communication system in which there are a plurality of master machines (control stations) conducting a frame synchronism. <P>SOLUTION: The master machine (the control station) 200 transmits control informations at every frame of a TDMA by the control channel, interrupts the transmission of the control channel by the frame determined by a random number at random from the frames transmitting no important control information, and changes the transmission into a receiving setting and measures an RSSI. Consequently, there is no state in which the disturbance waves of the control channels for other master machines (the control stations) cannot be detected completely, and the control channel can be changed over by detecting the interferences with other master machines. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radio apparatus that communicates by radio signals using the TDMA scheme, and relates to a radio communication system and a radio communication apparatus that detect interference in a control channel.

  In recent years, communication devices using wireless communication, such as cordless telephones, have become widespread. These wireless communication apparatuses are composed of a wireless communication apparatus that operates as one control station and one or more dependent stations. The cordless telephone is composed of a cordless telephone master unit connected to a public network operating as a control station and a cordless telephone slave unit operating as a subordinate station.

  Conventionally, in these cordless telephone apparatuses, when wireless communication is started, the communication channel to be used is in an idle state, and the noise magnitude and electric field strength (hereinafter RSSI) in the channel are set to predetermined values (thresholds). Confirmation is made by comparison, and wireless connection is performed (see Patent Document 1).

When in a standby state, that is, when a call channel is not set, the cordless telephone device transmits control information from the master unit to the slave unit via the control channel. Normally, the control channel is fixed, and whether or not there is noise of other cordless devices is detected by periodically performing RSSI measurement with the transmission setting of the base unit as the reception setting. When it is determined that the interference is large, the control channel is communicated in a good state by switching the current control channel to another idle channel.
Japanese Patent Laid-Open No. 5-304500

  The problem to be solved is that it is impossible to detect the interference of a plurality of cordless telephone master units that are performing frame synchronization.

  For example, in an office where a plurality of cordless telephone base units are installed in a state of interference, and in a system in which these telephone base units are frame-synchronized such as wireless PBX, RSSI measurement is performed periodically. (For example, once every 32 frames, measured with the same frame number), the reception setting is made simultaneously for the control channels of a plurality of telephone base units, and the control channel of the telephone base unit in the system is set. There is a problem that interference (jamming wave) cannot be detected. That is, if another cordless telephone base unit is set in the receiving state at the same timing when a certain cordless telephone base unit is set in the receiving state for RSSI measurement, this is controlled for the other cordless telephone base unit. Even in the case of a channel, since no signal is transmitted at that time, the interference of the control channel cannot be detected.

  The radio communication system and the radio communication apparatus according to the present invention are mainly characterized in that the RSSI measurement timing of the control channel is randomly set to enable interference detection under any environment.

The wireless communication system and the wireless communication apparatus of the present invention can detect interference in any environment by randomly setting the RSSI measurement timing of the control channel, and a plurality of cordless telephones that perform frame synchronization. There is an advantage that a good radio environment can be obtained by detecting the interference of the master unit and switching the control channel to another idle channel.

  The purpose of the present invention is to randomly control the RSSI measurement timing of the control channel with the object that a plurality of frame-synchronized control stations detect interference of the control channel, switch to another idle channel, and obtain a good radio environment. Realized by setting.

  A first invention made to solve the above problems is a control channel for transmitting a control signal from a control station. In a system for measuring RSSI, means for determining a frame for RSSI measurement with a random number, and control signal transmission The control station that synchronizes a plurality of frames (corresponding to cordless telephones) by randomly setting the RSSI measurement timing. It is possible to detect interference between the control channels of the parent device), switch the control channel to a channel without interference, and obtain communication of the control channel in a favorable wireless environment.

  A second invention made to solve the above-mentioned problem is that, in the means for switching the control channel from the measured RSSI, the means for comparing the measured RSSI with a threshold value that is a criterion for judging the interference wave, and the measured RSSI When the ratio that is equal to or greater than the threshold value is equal to or greater than the predetermined value, there is a means for switching the control channel. By switching the control channel at the ratio that the RSSI is equal to or greater than the threshold value, the RSSI measurement frame coincides by chance. Even in this case, there is an advantage that interference detection according to the wireless environment can be performed.

  According to a third aspect of the present invention, there is provided a system in which a plurality of control stations perform frame synchronization in a system in which a plurality of control stations perform frame synchronization using a unique number assigned to each of the plurality of control stations. When a unique number is assigned to each control station in a system having a plurality of control stations that are performing frame synchronization, by determining an RSSI measurement frame with the unique number There is an advantage that it is possible to realize a system in which the RSSI measurement timing does not coincide with a digital cordless telephone base unit other than itself in the system.

  According to a fourth aspect of the present invention for solving the above-mentioned problems, in the means for determining a frame for RSSI measurement, the control station has a means for avoiding a frame for transmitting important system information to a subordinate station. There is an advantage that interference can be detected without affecting the telephone cordless handset at all.

(Embodiment 1)
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS.

  FIG. 1 is a configuration diagram of a radio communication system according to Embodiment 1 of the present invention.

  Reference numeral 100 denotes a PBX main apparatus that is a private branch exchange connected to a public line. Reference numerals 101, 102, and 103 denote cordless telephone master units that are connected to the PBX main unit 100 by wire. Reference numerals 104, 105, and 106 are cordless telephone slaves that are registered in the cordless telephone master units 101, 102, and 103, respectively, and capable of wireless communication with the cordless telephone master units.

The cordless telephone base units 101, 102, and 103 are synchronized with a synchronization signal from the PBX main unit 100, and each cordless telephone base unit is in frame synchronization. Further, the cordless telephone slave units 104, 105, and 106 are synchronized with the cordless telephone master units 101, 102, and 103 by receiving control signals transmitted from the cordless telephone master units 101, 102, and 103, respectively. 104, 105, 106 and cordless telephone master units 101, 102, 103 perform TDMA digital communication.

  FIG. 2 is an explanatory diagram of a transmission / reception slot of the cordless telephone according to the present invention. Reference numeral 200 denotes a main body of the cordless telephone master units 101, 102, and 103. Reference numeral 206 denotes an antenna that transmits and receives radio signals. Reference numeral 201 denotes a call control unit 201 that controls outgoing and incoming calls of voice communication in a telephone. Reference numeral 202 denotes a voice communication channel generated by a call communication of the call control part 201 or a wireless communication connection by incoming call. A wireless communication management unit 202 manages a control channel and the like for transmitting wireless communication information to the slave units 104, 105, and 106. Reference numeral 203 denotes a wireless transmission unit 203 configured to perform transmission setting of transmission data set by the wireless communication management unit 202, and 205 represents a wireless reception unit 205 configured to perform wireless reception setting for processing a reception signal received by the antenna 206.

  An RSSI monitor management unit 204 obtains an RSSI measurement value from the wireless reception unit 205, performs wireless interference detection processing, and requests channel switching to the wireless communication management unit 202 when there is interference detection. The RSSI monitor management unit 204 also notifies the wireless transmission unit 203 and the wireless reception unit 205 of the cancellation of the RSSI measurement setting. The above processing units 201 to 205 detect interference in the communication channel and control channel in the wireless environment, and perform processing such as switching to an empty channel so that a better wireless environment can be obtained.

  FIG. 3 is an explanatory diagram of a transmission / reception slot of the cordless telephone according to the present invention. FIG. 3 shows the transmission slot and reception slot of the cordless telephone cordless handset and the base phone at the time of control channel transmission and RSSI measurement. In the first embodiment, the transmission slots on the control station side determined in advance in the radio communication system are four slots from slot 1 to slot 4, and the transmission slots on the dependent station side are slots 5 to 8 as well. 4 shows a time-division multiplex slot arrangement in which one frame is composed of four slots, and the time slot of the wireless communication system 1 has four transmission slots and four reception slots corresponding to the transmission slots. Composed.

  The cordless telephone base unit 200 transmits control information to the cordless telephone handset every frame using the transmission slot 1 in the figure as a control channel (S301). When performing RSSI measurement of the control channel (transmission slot 1), the cordless telephone base unit 200 sets the slot 1 used for normal transmission to the reception state, and performs RSSI measurement (S302). At this time, control information is not transmitted to the cordless telephone handset. The RSSI measurement of the control channel is performed by setting reception in the transmission slot in this way.

  In a system in which there are a plurality of cordless telephone master units that perform frame synchronization as shown in FIG. 1, the RSSI measurement is periodically performed on all cordless telephone master units, for example, once every 32 frames (0x0f, In the first embodiment of the present invention, the RSSI measurement frame is determined by a random number, and the interference wave of the control channel of another cordless telephone base unit cannot be detected at all in the case of being performed at 0x2f, 0x4f, 0x6f,. Is lost.

  Hereinafter, each step, which is a flowchart of the RSSI measurement frame determination process of the control channel of the present invention in FIG. 4, will be described.

  First, the current frame number Frame No is acquired (step 401).

It is determined whether the frame number Frame No acquired in step 401 is the RSSI measurement frame number Frame No Rssi. If the current frame number Frame No matches the RSSI measurement frame number Frame No Rssi, step 40
If no match is found, the process proceeds to step 407 (step 402).

  When the frame number Frame No is the RSSI measurement frame number Frame No Rssi, the RSSI measurement value is acquired (step 403).

  From the acquired RSSI measurement value, the wireless communication management unit 202 shown in FIG. 1 determines whether it is necessary to switch the control channel. If necessary, the process proceeds to step 405, and if not necessary, the process proceeds to step 406 (step 404).

  When the control channel needs to be switched, the wireless communication management unit 202 performs a control channel switching process and proceeds to step 406 (step 405).

  The next RSSI measurement frame number Frame No Rssi of the control channel is obtained from the random number x (step 406).

  Since the control channel is set for reception, it is set for transmission (step 407).

  Next, it is determined whether the current frame number Frame No is the previous frame of the RSSI measurement frame number Frame No Rssi. If it is the previous frame, return to Step 409, otherwise return to Step 401 (Step 408).

  If the current frame number Frame No is the previous frame of the RSSI measurement frame number Frame No Rssi, reception setting is performed on the control channel in order to perform RSSI measurement in the next frame (step 409).

  As described above, the RSSI measurement frame determination process is performed in the processes of Step 401 to Step 409, and the RSSI monitor cycle can be set at random by using the random number x, which matches the RSSI measurement timing of the cordless telephone master other than itself. The possibility of interference is reduced, and interference detection becomes possible.

  Note that the control in FIG. 4 may be realized by a processing device using a microcomputer. In that case, the control in FIG. 4 is executed as a part of a program of the microcomputer that controls the device. At this time, the random number x may be a pseudo-random number with a fixed period realized by a program. That is, the random number x may be a value other than a certain period.

  FIG. 5 is an explanatory diagram of the transmission / reception slot of the cordless telephone according to Embodiment 1 of the present invention. In the figure, the RSSI measurement frames of the cordless telephone master units 101 and 102 match, and interference between the cordless telephone master units 101 and 102 cannot be detected (S501). On the other hand, the interference of the cordless telephone base unit 103 can be detected by the cordless telephone base units 101 and 102 (S502). Further, since the RSSI measurement frame of the cordless telephone base unit 103 is different from that of the cordless telephone base units 101 and 102, interference can be detected. Since the next RSSI measurement frame is set by the random number of each parent device, it may match in each parent device, but may be different, and interference detection is possible in each parent device.

(Embodiment 2)
In Embodiment 1 of the present invention, when the cordless telephone base unit other than itself coincides with the RSSI measurement frame number by chance, if the determination is based on the continuous number of times, a low RSSI measurement value is obtained even once, If it is not determined, it is determined that switching is not necessary, and there is a case where the control channel cannot be switched even in a poor wireless environment.

  In the second embodiment of the present invention, in consideration of the fact that the RSSI measurement frames described in the first embodiment may coincide with each other, the determination of switching the control channel is performed based on the RSSI measurement value and the interference wave. The number of times determined is not the number of consecutive times, but the number of times determined during the specified number of measurements (hereinafter referred to as error rate).

  FIG. 6 shows a flowchart of a control channel switching determination process according to Embodiment 2 of the present invention. The process will be described according to each step.

  First, an RSSI measurement value RSSIm is acquired (step 601).

  The RSSI measurement count RSSICnt is counted (step 602).

  The RSSI threshold value RSSIs, which is the RSSI value determined as having interference in advance, is compared with the RSSI measurement value RSSIm. If the RSSI measurement value RSSIm is larger than the RSSI threshold RSSIs, the process proceeds to step 604, and if smaller, the process proceeds to step 605 (step 603).

  The number of times RSSI Err Cnt determined that there is an interference wave based on the RSSI measurement value RSSIm is counted (step 604).

  RSSI measurement number RSSI Cnt It is determined whether a certain measurement number RSSI Cnt L has been reached. If reached, the process proceeds to step 606, and if not, the process proceeds to 601 (step 605).

  It is determined whether the number of times RSSI Err Cnt is determined to be an interference wave is greater than threshold RSSI Err Cnt L. If larger, the process proceeds to Step 607, and if not, the process proceeds to Step 608 (Step 606).

  If the number of times it is determined in step 606 that there is an interference wave exceeds the threshold, it is determined that there is interference, and control channel switching processing is performed (step 607).

  When the number of times that the interference wave is determined in step 606 is smaller than the threshold, it is determined that there is no interference, and the RSSI measurement number RSSI Cnt and the number of times RSSI is determined that there is an interference wave without switching the control channel. Err Cnt is cleared (step 608).

  As described above, by performing the control channel switching determination process in the processing of step 601 to step 608, even if the RSSI measurement value is accidentally low and is not determined to be an interference wave, the switching is performed if the number of times the interference wave is determined is large. It is determined that it is necessary, and control channel switching processing is performed.

  In this way, it is possible to detect control channel interference in accordance with the radio environment.

(Embodiment 3)
The third embodiment of the present invention is a method for determining the RSSI measurement frame number by the unique number of each cordless telephone base unit when there are a plurality of cordless telephone base units performing frame synchronization in the same system. .

FIG. 7 is an explanatory diagram of the transmission / reception slot of the cordless telephone master according to the third embodiment of the present invention. The cordless telephone master units 101, 102, and 103 are assigned with unique numbers 1, 2, and 3, respectively. Frame number Frame No. for RSSI measurement performed once every 32 frames
Rssi is obtained from the unique number ID according to (Equation 1).

Frame No Rssi = (2ID-1) + 32n (n = 0, 1,...) (Formula 1)
The RSSI measurement frame number of the cordless telephone base unit 101 is 0x01, 0x21, 0x41,... The RSSI measurement frame number of the cordless telephone base unit 102 is 0x03, 0x23, 0x43,. Are 0x05, 0x25, 0x45, and so on. As shown in FIG. 7, the RSSI measurement frame numbers of the cordless telephone master units 101, 102, 103 do not match (S701, S702, S703).

  In the third embodiment, since the unique number of each cordless telephone base unit is set uniquely in the same system, the RSSI measurement frame number can be determined uniquely, so that the RSSI measurement frame number does not match at all. Accordingly, it is possible to detect interference of a cordless telephone base unit other than itself within the same system, and transmission of a control channel can be performed in a better wireless environment.

(Embodiment 4)
In the fourth embodiment of the present invention, RSSI measurement is not performed in a frame in which important information is broadcast to the cordless telephone handset, so that the operation of the cordless telephone handset according to the control information from the cordless telephone base phone is not affected. To.

  The cordless telephone base unit of the present invention transmits unique information, system information, paging, etc. in even-numbered frames. If these pieces of information cannot be received by the cordless telephone cordless handset, the use status of the slot of the cordless telephone cordless handset cannot be grasped, and a failure occurs when a call channel is established. When the cordless telephone cordless handset is intermittently received, the received frame is a frame number of 0xX0 (X = 0, 1, 2, 3,..., F) in hexadecimal, and the master unit's unique information, system information, etc. Cannot receive.

  FIG. 8 shows an explanatory diagram of a transmission / reception slot of a cordless telephone according to Embodiment 4 of the present invention. The cordless telephone cordless handset receives control information from the cordless telephone master phone with the frame number 0x00 (S801), and stops receiving processing from the next frame. The cordless telephone base unit performs RSSI measurement with the frame number 0x01. The cordless telephone cordless handset receives the frame number 0x10, receives the control information of the cordless telephone base phone again, updates the information, and stops the receiving process from the next frame. By setting the RSSI measurement frame to the odd frame, the control channel of the even frame is always transmitted.

  As described above, the cordless telephone handset cannot receive important control information of the cordless telephone base unit, and the cordless telephone base unit performs RSSI measurement and can detect interference.

  The present invention has an advantage that a good radio environment can be provided because interference can be avoided by detecting interference in a system in which a plurality of cordless master units such as a cordless telephone and a wireless PBX are present.

The block diagram of the radio | wireless communications system which concerns on Embodiment 1 of this invention 1 is a block diagram of a cordless telephone master device according to a first embodiment of the present invention. Explanatory drawing of the transmission / reception slot of the cordless telephone of the present invention Flowchart of RSSI measurement frame determination processing of control channel of the present invention Explanatory drawing of the transmission / reception slot of the cordless telephone which concerns on Embodiment 1 of this invention Flowchart of control channel switching determination processing according to Embodiment 2 of the present invention Explanatory drawing of the transmission / reception slot of the cordless telephone main unit based on Embodiment 3 of this invention Explanatory drawing of the transmission / reception slot of the cordless telephone which concerns on Embodiment 4 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 PBX main unit 101,102,103 Cordless telephone master unit 104,105,106 Cordless telephone cordless handset 200 Cordless telephone main unit main body 201 Call control part 202 Wireless communication management part 203 Wireless transmission part 204 RSSI monitor management part 205 Wireless reception part 206 Antenna

Claims (9)

A wireless communication system comprising a control station that transmits a control signal serving as a reference for synchronization and at least one subordinate station that receives the control signal and operates in synchronization with transmission / reception timing of the control station,
The control station and the dependent station perform slot time division communication in which one section of a predetermined time interval is divided by a predetermined time,
The control station normally transmits a control signal serving as a reference for synchronization in a predetermined slot in the interval, determines a frame for RSSI measurement using a random number, and controls the predetermined slot in the determined frame. Stop sending signals and measure RSSI,
A wireless communication system. The control station includes a means for comparing the measured RSSI with a threshold value that is a criterion for determining an interference wave, and a means for switching a control channel when a ratio that the measured RSSI is equal to or greater than a threshold value is equal to or greater than a predetermined value. The wireless communication system according to claim 1, further comprising: 2. The wireless communication system according to claim 1, wherein when determining a frame for RSSI measurement, the control station avoids a frame that should transmit important system information to the dependent station. A radio communication system having a plurality of control stations that are frame-synchronized with each other and having a dependent station that performs slot time-division communication in which one section of a predetermined time interval with the control station is divided by a predetermined time Because
The control station normally transmits a control signal serving as a reference for synchronization in a predetermined slot in the section;
Means for determining a frame for measuring RSSI with a random number;
Means for stopping the transmission of the control signal in the predetermined slot in the determined frame and measuring RSSI;
A wireless communication system comprising: means for switching a control channel according to a measurement result of RSSI. A time division multiplexing (hereinafter referred to as TDMA) system in which one section (hereinafter referred to as a frame) of a predetermined time interval is divided into N at a predetermined time (hereinafter referred to as a slot) and communication is performed in each of the slots. A control station that transmits a control signal serving as a reference for TDMA synchronization in at least one TDMA slot, and receives at least the control signal and operates in synchronization with the TDMA timing of the control station. A wireless communication system comprising one dependent station,
In a system for measuring RSSI (Received Signal Strength Indication), which is a magnitude of noise and electric field strength, in a control channel for transmitting a control signal from a digital cordless telephone master as the control station, a frame for performing the RSSI measurement is a random number. A wireless communication apparatus comprising: means for determining at step S3; means for measuring the RSSI at the timing of control signal transmission; and means for switching a control channel from the RSSI. In the means for switching the control channel from the measured RSSI, the means for comparing the measured RSSI with a threshold value that is a criterion for determining an interference wave, and the ratio that the measured RSSI is equal to or greater than the threshold value is equal to or greater than a predetermined value. 6. The wireless communication system according to claim 5, further comprising means for switching a control channel. 6. The radio according to claim 5, further comprising means for determining a frame in which a plurality of control stations perform frame synchronization and performing RSSI measurement based on a unique number assigned to each of the plurality of digital cordless telephone master units. Communications system. 6. The wireless communication system according to claim 5, wherein when determining a frame for RSSI measurement, the control station avoids a frame that should transmit important system information to the dependent station. A wireless communication device that performs slot time-division communication by dividing one section of a predetermined time interval with a communication partner by a predetermined time,
Means for transmitting a control signal which is a reference for synchronization in a predetermined slot in the section,
Means for determining a frame for measuring RSSI with a random number;
Means for stopping the transmission of the control signal in the predetermined slot in the determined frame and measuring RSSI;
And a means for switching a control channel in accordance with an RSSI measurement result.

Images