JP3796484B2 - Downlink quality measurement equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, bidirectional wireless communication between a single base station and a single or a plurality of subscriber stations is performed using a TDD (Time Division Duplex) / TDMA (Time Division Multiple Access) method or FDD (Frequency Division Duplex). TECHNICAL FIELD The present invention relates to a downlink quality measuring apparatus for calculating downlink quality in more detail in transmission of a downlink radio frame from a base station to a subscriber station in a radio communication system using the / TDMA scheme.
[0002]
[Prior art]
Conventionally, the transmission quality of data transmission has been defined by a bit error rate (= number of erroneously received bits / total number of transmitted bits) or a block error rate (= number of erroneously received blocks / total number of transmitted blocks) (non-patent literature). 1).
[0003]
The downlink quality of a wireless communication system in which a single base station with a fixed installation location and a single or a plurality of subscriber stations are connected by the TDD / TDMA method has been measured as follows.
[0004]
First, the base station performs error correction using a Reed-Solomon code or the like on each packet of a single packet or a plurality of packets included in the downlink radio frame, and transmits the packet to the subscriber station as a downlink radio frame.
[0005]
Next, in the subscriber station, from the total number of packets included in the received downlink radio frame (number of received packets) and the number of packets discarded due to error detection out of the number of packets (number of received packets discarded) The wireless packet discard rate is calculated.
[0006]
This wireless packet discard rate is calculated by the number of discarded received packets ÷ the number of received packets.
[0007]
[Non-Patent Document 1]
Iwao Hosaka, “Introduction to Data Communication Systems”, Ohmsha, December 10, 1985, p. 103-p. 105
[0008]
[Problems to be solved by the invention]
By the way, the bit error rate, the block error rate, or the wireless packet discard rate described above is calculated on the assumption that all transmission data transmitted from the transmission side is normally received on the reception side.
[0009]
However, in the case of wireless data transmission, the quality of the transmission line is generally poor compared to wired data transmission. For example, the subscriber may be disconnected due to a momentary disconnection of the transmission line due to weather conditions such as rain or snow, or disconnection for a certain period. The station side may not be able to receive downlink radio frames. Further, there are cases where the subscriber station cannot receive the downlink radio frame due to a momentary interruption of the transmission path due to a radio wave obstacle such as a bird or laundry, or disconnection for a certain period.
[0010]
In such a case, the wireless packet discard rate is received when the transmission line is interrupted because it is assumed that all the packets constituting the downlink wireless frame transmitted from the base station can be received by the subscriber station. No consideration is given to a packet that could not be received or a packet that was disconnected for a certain period and could not be received. For this reason, there is a problem in that the value of the radio packet discard rate becomes small and cannot be reflected in the details of the actual downlink quality.
[0011]
The present invention has been made in view of such problems, and an object of the present invention is to provide a downlink quality measuring apparatus that can calculate downlink quality in more detail.
[0012]
Another object of the present invention is to provide a downlink quality measuring apparatus that allows a base station to easily acquire downlink quality calculated by a subscriber station.
[0013]
[Means for Solving the Problems]
A downlink quality measurement apparatus according to the present invention is a downlink quality measurement apparatus for a wireless communication system in which a single base station and a single or a plurality of subscriber stations are connected by a TDD scheme or an FDD scheme. A demodulating circuit that receives a downlink radio frame including a packet and outputs a reception synchronization signal for each received radio frame; resets for each reception synchronization signal; outputs a reception frame period signal; and When no sync signal is input, the frame period signal output unit outputs a free-running frame period signal by self-running, and the received frame period signal and the free-running frame period signal are counted to output the number of frames. A frame number counter for counting, a synchronization number counter for counting the reception synchronization signal and outputting the number of synchronizations; , With Then, from the number of frames and the number of synchronizations, the number of missing frames in the downlink radio frame is obtained as (number of frames−number of synchronizations). (Invention of Claim 1)
[0014]
According to the present invention, the number of synchronizations (corresponding to the number of frames actually received) counted by the reception synchronization signal output for each radio frame actually received at the subscriber station, and the demodulation circuit. The number of frames including the frame when the reception synchronization signal could not be output {the total number of frames that could actually be received (the number of received frame periodic signals) and the number of frames that could not be received (the number of free-running frame periodic signals) Corresponds to a number. } Is output, so The number of missing frames in the downlink radio frame can be obtained as (number of frames−number of synchronizations) The downlink quality can be calculated in more detail.
[0015]
In this case, the demodulation circuit further extracts and outputs a received packet from the received one radio frame, counts the received packet, and outputs a received packet number counter. An error detector that detects an error of the received packet and outputs an error detection signal, and an erroneously received packet number counter that counts using the error detection signal as a trigger and outputs the number of erroneously received packets is provided. Of the packets, the number of received packets that could be received normally without error, or the number of received packets that could be received normally as a result of error correction, and the reception was successful but the error could not be corrected and could not be received as a result Therefore, it is possible to calculate the number of erroneously received packets that are considered erroneously received packets. From the number of missing frames, the number N of fixed-length packets included in one downlink radio frame, and the number of erroneously received packets, the number of discarded wireless packets is calculated as (number of erroneously received packets + number of missing frames × N). To calculate the downlink quality in more detail. (Invention of Claim 2)
[0016]
Here, from the number of frames, the number of synchronizations, the number of received packets, the number of erroneously received packets, and the number N of fixed downlink packets in one radio frame, a radio packet discard rate is represented by { More detailed packet discard by providing a wireless packet discard rate calculator obtained by the number of erroneously received packets + (number of frames−number of synchronizations) × N} ÷ {number of received packets + (number of frames−number of synchronizations) × N} The rate can be calculated (the invention according to claim 3). Note that (number of frames−number of synchronizations) means the number of missing frames that could not be received at the subscriber station.
[0017]
Further, the uplink of one radio frame includes a control channel for transmitting the calculated radio packet discard rate, so that the base station knows the radio packet discard rate calculated by the subscriber station. (Invention of claim 4).
[0018]
Of course, a packet discard rate calculator is provided in the base station, and the number of frames, the number of synchronizations, the number of received packets, the number of erroneously received packets, and the number N of fixed downlink packets in one radio frame N May be calculated from the subscriber station to the base station so that the base station collectively calculates the wireless packet discard rate.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0020]
FIG. 1 shows an overall configuration of a wireless communication system 10 to which an embodiment of the present invention is applied.
[0021]
The wireless communication system 10 is used as a P-MP (Point to Multi-Point) type that provides a fixed wireless access service to a plurality of subscribers.
[0022]
The wireless communication system 10 is basically capable of two-way communication with a base station 11 fixed to a building or a utility pole, and the fixed base station 11 via a wireless line. A plurality of subscriber stations 21 (1) to 21 (3) (referred to as subscriber stations 21 as representatives) distributed in a company or home.
[0023]
The wireless line is established through wireless communication between the antenna 12 of the base station 11 and the antennas of the plurality of subscriber stations 21.
[0024]
Each subscriber station 21 is connected to terminals 20 (1) to 20 (3) (typically referred to as terminals 20) such as personal computers by wire or wirelessly. Each terminal 20 and each subscriber station 21 can be integrated. On the other hand, the base station 11 can be connected to a terminal 14 having a function of a personal computer, and is connected to a network 13 mainly by wire. The terminal 14 of the base station 11 is operated by an administrator of the wireless communication system 10, for example. The terminal 14 of the base station 11 can be always connected via the network 13.
[0025]
Each subscriber station 21 can access the network 13 via the radio line and the base station 11. As the network 13, an IP (Internet Protocol) network connected to a WWW (World Wide Web) server or the like (not shown) can be used.
[0026]
For communication between the base station 11 and the plurality of subscriber stations 21, bidirectional communication employing the TDD / TDMA scheme is possible. In this case, a common radio frequency, for example, a 26 [GHz] band is assigned between the base station 11 and the plurality of subscriber stations 21, and efficient communication is possible due to a difference in time slots to be used.
[0027]
For communication between the base station 11 and the plurality of subscriber stations 21, an FDD / TDMA system, which will be described later, can be adopted instead of the TDD / TDMA system. In either case of the TDD / TDMA scheme or the FDD / TDMA scheme, the downlink direction is a TDM (Time Division Multiplex) scheme, and the uplink direction is a TDMA scheme.
[0028]
FIG. 2 shows a configuration of a radio frame (one radio frame) based on the TDD scheme for performing communication between a plurality of subscriber stations 21 and the base station 11. The period of one radio frame is selected to be a fixed period, for example, 1 [ms], etc., of the order of 1 to 10 [ms]. Of course, a shorter period or a longer period can be selected as the period of one radio frame in relation to hardware or the like. The frame of one radio frame having a fixed period is different from a frame such as a variable-length ether frame.
[0029]
One radio frame includes a downlink area, an uplink area, and a guard time TS16. The downlink region includes a downlink header region TS11 and a downlink data region TS12. The uplink region includes a DMF (Delay Measurement Frame) region TS13, a slot demand region TS14, and an uplink data region TS15 that are time zones for measuring propagation delay between the base station 11 and each subscriber station 21. . Note that the DMF area TS13 stores the radio packet discard rate calculated on the subscriber station 21 side or the data necessary to calculate the radio packet discard rate when measuring the propagation delay of each subscriber station 21. Transmit from each subscriber station 21 to the base station 11. The DMF region TS13 also has a control channel function.
[0030]
In the downlink area of one radio frame, the downlink header area TS11 includes a preamble area TS17 for generating a reception synchronization signal for each radio frame, a base station number area TS18, a frame position designation area TS19, and DMF transmission permission. The command area TS20 includes control commands such as, and the slot allocation area TS21.
[0031]
In the downlink region of one radio frame, the remaining downlink data region TS12 is divided into a plurality of time slots, and a fixed downlink packet (also simply referred to as a packet) Pd is assigned to each. Each downlink fixed length packet Pd includes a subscriber station number Pd1, control information Pd2 such as adjacent packet presence / absence information, fixed length data Pd3 which is actual data, and an error detection code Pd4.
[0032]
In the uplink region of one radio frame, the uplink data region TS15 is divided into a plurality of time slots, and an uplink fixed length packet (also simply referred to as a packet) Pu is allocated to each. Each uplink fixed-length packet Pu is composed of guard time Pu1, preamble Pu2, subscriber station number Pu3, control information Pu4 including adjacent packet presence / absence information, etc., fixed-length data Pu5 that is actual data, and error detection code Pu6. ing.
[0033]
Note that the configurations of the upper and lower data areas TS12 and TS15 are common to the TDD / TDMA system and the FDD / TDMA system.
[0034]
The data length of one downlink fixed length packet Pd or one uplink fixed length packet Pu is selected to be 64 bytes or 128 bytes, for example.
[0035]
FIG. 3 shows the configuration of each subscriber station 21 as an example. The subscriber station 21 basically includes an antenna 22, a high frequency circuit 32, and a communication control circuit 33 connected to the high frequency circuit 32 and the terminal 20.
[0036]
The high frequency circuit 32 includes a receiver 41, a transmitter 42, and a changeover switch 43 disposed between the transceivers 41 and 42 and the antenna 22.
[0037]
The transmitter 42 of the high frequency circuit 32 converts the intermediate frequency signal supplied from the communication control circuit 33 into a radio frequency signal by a built-in mixer and converts the radio frequency high frequency signal with a built-in power amplifier. The power is amplified and supplied to the antenna 22 via the changeover switch 43.
[0038]
The receiver 41 of the high-frequency circuit 32 inputs a radio frequency high-frequency signal (a radio frame modulation signal) received by the antenna 22 through the change-over switch 43, amplifies it with a built-in low noise amplifier, and then incorporates it. The frequency is converted into a radio frame of an intermediate frequency by the mixer, and supplied to the modulation / demodulation circuit 51 of the communication control circuit 33.
[0039]
The demodulating unit constituting the modem circuit 51 demodulates the data in the downlink region in the radio frame received by the receiver 41 by an A / D converter (not shown) and a PSK demodulator (not shown), and has a fixed downlink length. The packet Pd is supplied to a TDD-TDM / TDMA control circuit (hereinafter referred to as a TDD / TDMA control circuit) 52. The TDD / TDMA control circuit 52 includes a radio packet discard rate calculation device 202.
[0040]
The downlink fixed length packet Pd demodulated by the modem circuit 51 is hereinafter referred to as a received packet (downlink fixed length packet) Pd.
[0041]
Further, the modulation unit constituting the modem circuit 51 converts the data in the uplink region in the radio frame supplied from the TDD / TDMA control circuit 52 into a D / A converter (not shown) and a PSK modulator (not shown). Modulates and supplies to the transmitter 42.
[0042]
In addition to the modem circuit 51 and the TDD / TDMA control circuit 52, the communication control circuit 33 includes a communication interface circuit 53, a downlink reception buffer 61, an uplink transmission buffer 62, and a packet number measurement unit 63 connected to the terminal 20.
[0043]
The packet number measuring unit 63 periodically measures the number of packets accumulated in the uplink transmission buffer 62 for each period of one radio frame, and transmits this to the TDD / TDMA control circuit 52 as information on the slot demand 71. Information on the slot demand 71 is notified from the TDD / TDMA control circuit 52 to the base station 11 through the modulation / demodulation circuit 51, the transmitter 42, the changeover switch 43 and the antenna 22 in the time zone of the slot demand region TS14 of one radio frame in FIG. Is done.
[0044]
FIG. 4 shows a configuration example of the downlink quality measuring apparatus 200 of this embodiment that constitutes the subscriber station 21. Downlink quality measuring apparatus 200 includes modulation / demodulation circuit 51 and radio packet discard rate calculation apparatus 202 in TDD / TDMA control circuit 52.
[0045]
The wireless packet discard rate calculating apparatus 202 includes a frame period signal output circuit 204 and a synchronization number counter 206 for receiving one reception synchronization signal output from the modulation / demodulation circuit 51 (one pulse) for each received wireless frame. In addition to an error detector 208 and a received packet number counter 212, a frame number counter 210, an erroneously received packet number counter 214, and a wireless packet discard rate calculator 216 are provided.
[0046]
The frame cycle signal output circuit 204 includes a timer 205. When the radio frame received by the receiver 41 is normally demodulated by the modulation / demodulation circuit 51, one reception synchronization signal is sent from the modulation / demodulation circuit 51 every 1 [ms] corresponding to one radio frame. At this time, the frame period signal output circuit 204 outputs one (one pulse) frame period signal (referred to as a reception frame period signal) corresponding to the normal reception synchronization signal.
[0047]
At the same time, the frame cycle signal output circuit 204 counts and counts the system clock by the timer 205 and creates a self-running frame cycle signal (referred to as a free-running frame cycle signal) every 1 [ms]. . If the next reception synchronization signal is not input even after 1 [ms] has elapsed since the reception frame period signal was output, the free-running frame period signal is output as the frame period signal. In this case, the received frame period signal corresponds to the number of radio frames transmitted from the base station 11 and actually received and demodulated normally by the subscriber station 21, and the free-running frame period signal is transmitted from the base station 11. This corresponds to the number of radio frames that have been demodulated by the subscriber station 21 but are not normally demodulated (referred to as the number of missing frames).
[0048]
The frame number counter 210 counts frame period signals (received frame period signal and free-running frame period signal), and outputs the number of frames as a count value to the wireless packet discard rate calculator 216.
[0049]
The synchronization number counter 206 counts the reception synchronization signal and outputs the number of synchronizations that is a count value to the wireless packet discard rate calculator 216. In this case, the number of times of synchronization matches the count value of the received frame period signal.
[0050]
The error detector 208 performs error detection and correction of the received packet (downlink fixed-length packet) Pd, which is the downlink fixed-length packet Pd demodulated by the modem circuit 51, and detects an error and detects the error. One (one pulse) error detection signal corresponding to one received packet (downlink fixed length packet) Pd is output to the erroneous received packet number counter 214. The error detector 208 supplies the fixed-length data Pd3 to the downlink reception buffer 61, which is normal in the received packet (downlink fixed-length packet) Pd and which is normal after correcting the error.
[0051]
The erroneously received packet counter 214 counts using the error detection signal as a trigger, and uses the count value (one count value for one error detection signal) as the number of erroneously received packets as a radio packet discard rate calculator 216. Output to.
[0052]
The reception packet number counter 212 counts the number of packets included in one downlink radio frame in synchronization with the reception synchronization signal, and outputs the count value to the radio packet discard rate calculator 216 as the number of received packets.
[0053]
The wireless packet discard rate calculator 216 is configured to measure the number of frames and the synchronization by the frame number counter 210 during a measurement period (for example, every minute, one minute can be arbitrarily set) according to a counter control signal output by itself. Based on the number of synchronizations by the number counter 206, the number of erroneously received packets by the erroneously received packet number counter 214, and the number of received packets by the received packet number counter 212, a wireless packet discard rate shown in the following equation (1) is calculated.
Wireless packet discard rate = {number of erroneously received packets + (number of frames−number of synchronizations) × N} ÷ {number of received packets + (number of frames−number of synchronizations) × N} (1)
[0054]
As described above, in equation (1), (number of frames−number of synchronizations) is a frame that could not be demodulated by the modem 51, that is, a frame that could not be received by the antenna 22 and the receiver 41 of the subscriber station 21. Therefore, the expression (1) can be replaced with the expression (2).
Wireless packet discard rate = {number of erroneously received packets + number of missing frames × N} ÷ {number of received packets + number of missing frames × N} (2)
[0055]
Here, N is the number of downlink fixed-length packets Pd for each subscriber station 21 included in one radio frame. When the number of packets is always fixed, a fixed value and the number of packets fluctuate dynamically. If so, set the expected value.
[0056]
The calculated wireless packet discard rate or the number of erroneously received packets, the number of frames, the number of synchronizations, the number N of fixed-length packets in the frame, and the number of received packets for calculating this wireless packet discard rate Each subscriber station 21 can be included in the DMF region TS13 output in a predetermined order and transmitted to the base station 11. In this case, the base station 11 that has received this information calculates, for example, the wireless packet discard rate for each subscriber station 21 in the terminal 14 and stores it in the storage device. Quality can be managed.
[0057]
FIG. 5 shows a configuration of the base station 11 as an example. The base station 11 basically includes an antenna 12, a high frequency circuit 132, and a communication control circuit 34 connected to the high frequency circuit 132 and the network 13.
[0058]
The configuration and operation of the high-frequency circuit 132 are the same as those of the high-frequency circuit 32 of the subscriber station 21 shown in FIG.
[0059]
The communication control circuit 34 includes a modulation / demodulation circuit 151, a TDD-TDM / TDMA (referred to as TDD / TDMA) control circuit 152, a communication interface circuit 153 connected to the network 13, a slot allocation unit 54, and a reception buffer 64 for each uplink subscriber station. A downlink subscriber station transmission buffer 65 and a packet number measuring unit 66 are provided.
[0060]
The packet number measurement unit 66 periodically measures the number of packets for each subscriber station 21 stored in the transmission buffer 65 for each downlink subscriber station for each period of one radio frame, and transmits this to the slot allocation unit 54. . The TDD / TDMA control circuit 152 extracts information on the slot demand 71 of each subscriber station 21 notified in the time zone of the slot demand region TS14 of one radio frame in FIG. 2 and transmits the information to the slot allocation unit 54.
[0061]
The slot allocation unit 54 determines information on the slot allocation 72 based on the number of packets for each subscriber station 21 and the information on the slot demand 71 and notifies the TDD / TDMA control circuit 152 of the information.
[0062]
The allocation of uplink time slots to each subscriber station 21 is notified in the time slot of the slot allocation region TS21 in one radio frame in FIG.
[0063]
When the communication interface circuits 53 and 153 of each subscriber station 21 and base station 11 include a CPU (Central Processing Unit) and are configured by a microcomputer or the like, various programs are installed in a ROM (Read Only Memory). In the case where it is configured to be executed by the CPU and configured as hardware, it is converted into an ASIC (Application Specific Integrated Circuit) and a predetermined function is executed.
[0064]
The radio communication system 10 to which an embodiment of the present invention is applied is basically configured as described above. Next, the overall operation and details of the downlink quality measuring apparatus 200 will be described. This will be described in the order of operation.
[0065]
General overall operation
For example, randomly generated variable-length data such as an Ethernet frame supplied from the terminal 20 to the subscriber station 21 is divided into uplink fixed-length packets Pu by the communication interface circuit 53 of the subscriber station 21. Is done. At this time, the communication interface circuit 53 further adds control information Pu4 including recombination information such as adjacent packet presence information, error detection code Pu6, and the like to each uplink fixed-length packet Pu.
[0066]
Each uplink fixed length packet Pu is assigned a slot according to the contents of the slot assignment area TS21 from the base station 11, and is transmitted from each subscriber station 21 functioning as a transmission side device through a wireless line.
[0067]
Each uplink fixed-length packet Pu received at the base station 11 functioning as a receiving-side device is recombined by the communication interface circuit 153 based on the control information Pu4 and the like, and the presence or absence of a packet is detected. If there is no omission, the recombined frame is output as data to the network 13 side.
[0068]
On the other hand, the same applies to the data supplied from the network 13 to the base station 11. In this case, the data is divided into fixed downlink packets Pd by the communication interface circuit 153 of the base station 11 functioning as a transmitting side device. At this time, recombining information such as adjacent packet presence / absence information is added to each downlink fixed length packet Pd as control information Pd2 and transmitted to a subscriber station 21 functioning as a receiving side device through a wireless line.
[0069]
The downlink fixed-length packet Pd received by the communication interface circuit 53 of the corresponding subscriber station 21 is recombined based on the control information Pd2, the presence or absence of a packet is detected, and when there is no packet loss It is transmitted to the terminal 20.
[0070]
The above description is a general description of the overall operation of the radio communication system 10, and then the detailed operation of the downlink quality measuring apparatus 200 will be described.
[0071]
At this time, first, a counter control signal for starting counting is output from the wireless packet discard rate calculator 216, and the counter values of the frame number counter 210, the synchronization number counter 206, the erroneously received packet number counter 214, and the received packet number counter 212 are counted. Is reset to zero.
[0072]
When the modulation / demodulation circuit 51 of the subscriber station 21 receives the downlink radio frame received through the antenna 22 via the receiver 41, it outputs one reception synchronization signal, which is a reception pull-in signal synchronized with the preamble TS 17, as a frame period signal output. Output to the circuit 204, the synchronization counter 206, and the error detector 208. Further, the modem circuit 51 outputs a received packet (downlink fixed-length packet) Pd to the error detector 208 and the received packet number counter 212 in synchronization with the output of the reception synchronization signal.
[0073]
When receiving the reception synchronization signal, the frame period signal output circuit 204 resets a built-in timer, generates one reception frame period signal, and outputs it to the frame number counter 210. At this time, if the frame period signal output circuit 204 cannot receive the reception synchronization signal for a predetermined period, it generates one free-running frame period signal generated by the timer and supplies it to the frame number counter 210. Output.
[0074]
The frame number counter 210 counts the received frame period signal and the free-running frame period signal, that is, increments the count value of the number of frames as a trigger.
[0075]
The synchronization number counter 206 increments the count value of the number of synchronizations using the reception synchronization signal as a trigger. The number of synchronizations is equal to the count value of the received frame period signal.
[0076]
When the error detector 208 receives the received packet (downlink fixed length packet) Pd synchronized with the reception synchronization signal, the error detector 208 performs error correction and discards the received packet (downlink fixed length packet) Pd that could not be corrected at the same time. The detection signal is output to the erroneous reception packet number counter 214. The normally demodulated reception packet (downlink fixed-length packet) Pd and the error-corrected reception packet (downlink fixed-length packet) Pd are sent to the downlink reception buffer 61.
[0077]
The erroneously received packet number counter 214 increments a count value of the erroneously received packet number using an error detection signal as a trigger.
[0078]
The reception packet number counter 212 uses the reception synchronization signal as a trigger to increment the number of reception packets by the number of reception packets (downlink fixed-length packets) Pd included in one downlink radio frame.
[0079]
When the counter control signal for counting is output from the wireless packet discard rate calculator 216, the count values of the frame number counter 210, the synchronization number counter 206, the erroneously received packet number counter 214, and the received packet number counter 212 are latched. Then, the number of frames, the number of synchronizations, the number of erroneously received packets, and the number of received packets, which are the latched count values, are taken into the wireless packet discard rate calculator 216.
[0080]
At this time, the wireless packet discard rate calculator 216 calculates the wireless packet discard rate of the above-described equation (1).
[0081]
Then, after the count value is taken into the wireless packet discard rate calculator 216, a counter control signal for starting counting is output again from the wireless packet discard rate calculator 216 at a predetermined time, and the frame number counter 210 The counter values of the synchronization number counter 206, the erroneously received packet number counter 214, and the received packet number counter 212 are reset to zero, and counting for the next wireless packet discard rate calculation is started.
[0082]
The above description is the detailed operation of the downlink quality measuring apparatus 200.
[0083]
Next, FIG. 6 shows a configuration example of the FDD subscriber station 21A. FIG. 7 shows a configuration example of the FDD-type base station 11A. FIG. 8 shows the configuration of an FDD radio frame.
[0084]
6 of the FDD system and the subscriber station 21 of FIG. 3 of the TDD system, the base station 11A of FIG. 7 of the FDD system, the base station 11 of FIG. 5 of the TDD system, and the FDD system In the radio frame of FIG. 8 and the radio frame of FIG. 2 of the TDD system described above, the same reference numerals are assigned to corresponding elements, and detailed description thereof is omitted.
[0085]
Since the FDD scheme is frequency multiplexing, different radio frequencies are used in the uplink direction and the downlink direction. Therefore, in the FDD system, the change-over switches 43 and 143 constituting the TDD type high frequency circuits 32 and 132 are replaced with diplexers 44 and 144, respectively, as shown in FIGS. As is well known, the diplexers 44 and 144 are composed of a band-pass filter for reception frequency and a band-pass filter for transmission frequency. The diplexers 44 and 144 lead output signals from the transmitters 42 and 142 to the antennas 12 and 22, respectively. The signal transmitted and received by the antennas 12 and 22 is guided to the receivers 41 and 141 side.
[0086]
On the other hand, as is clear from FIG. 2 and FIG. 8, one radio frame is divided into a downlink and an uplink in series in the TDD method, whereas in the FDD method, the radio frame is divided. The downlink radio frame and the uplink radio frame are configured in parallel.
[0087]
The downlink data area in the downlink radio frame shown in FIG. 8 has the same configuration as the downlink fixed length packet Pd shown in the downlink data area TS12 of FIG.
[0088]
Similarly, the uplink data area in the uplink radio frame shown in FIG. 8 has the same configuration as the uplink fixed length packet Pu shown in the uplink data area TS15 in FIG.
[0089]
Therefore, the downlink quality measuring apparatus 200 (modem / demodulation circuit 51 and radio packet discard rate calculating apparatus 202) shown in FIG. 4 calculates the more detailed radio packet discard rate shown in equation (1) as in the TDD scheme. can do.
[0090]
As described above, according to the above-described embodiment, the downlink frames from the base stations 11 and 11A are transmitted to the subscribers by, for example, instantaneous transmission line disconnection or disconnection for a certain period due to weather conditions such as rain or snowfall. When the station 21 or 21A cannot receive the signal, or when the subscriber station 21 or 21A cannot receive the signal due to a momentary interruption of the transmission path or a certain period of disconnection due to a radio wave obstacle such as a bird or laundry. Furthermore, it is a free-running output of the timer 205 built in the frame period signal output circuit 204 that the downlink frame is lost even when the subscriber station 21 or 21A cannot receive the signal due to some other factor. Since it is detected by the free-running frame period signal and added to the downlink quality information, more detailed downlink quality information can be obtained.
[0091]
The detailed downlink quality information can also be known by the terminal 14 on the base station 11 or 11A side by transmitting it from the subscriber station 21 side to the base station 11 or 11A side by using an uplink radio frame.
[0092]
The present invention is not limited to the above-described embodiment, and may be applied to, for example, a bidirectional optical line in which a base station and a subscriber station are connected by an optical fiber instead of a wireless line as a transmission line. Of course, various configurations can be adopted without departing from the gist of the present invention.
[0093]
【The invention's effect】
As described above, according to the present invention, since the free-running frame period signal corresponding to the number of frames that could not be actually received by the subscriber station is generated, the downlink quality can be calculated in more detail. Can do.
[0094]
Also, the downlink quality calculated by the subscriber station can be easily obtained by the base station.
[0095]
As a result, it is possible to obtain a radio packet discard rate that represents downlink quality in more detail at the subscriber station and the base station as compared with the radio packet discard rate calculated by the prior art that does not consider the number of frames that could not be received. it can.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a wireless communication system to which an embodiment of the present invention is applied.
FIG. 2 is a configuration diagram of a TDD radio frame.
FIG. 3 is a block diagram showing a configuration of a TDD subscriber station.
FIG. 4 is a block diagram showing a configuration of a downlink quality measurement prime minister of this embodiment.
FIG. 5 is a block diagram showing a configuration of a TDD base station.
FIG. 6 is a block diagram showing a configuration of an FDD subscriber station.
FIG. 7 is a block diagram showing a configuration of an FDD base station.
FIG. 8 is a configuration diagram of an FDD radio frame.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Wireless communication system 11, 11A ... Base station
12, 22 ... Antenna 13 ... Network
14, 20 ... Terminal 21, 21A ... Subscriber station
32, 132 ... high frequency circuit 33, 34 ... communication control circuit
41 ... Receiver 42 ... Transmitter
43, 143 ... changeover switch 44, 144 ... diplexer
51, 151 ... modulation / demodulation circuit
52, 152 ... TDD / TDMA control circuit
53, 153 ... Communication interface circuit
54 ... Slot allocation unit 61 ... Downlink reception buffer
62: Upstream transmission buffer 63, 66: Number of packets measuring unit
64: Receive buffer for each upstream subscriber station
65: Transmission buffer for each downlink subscriber station
71 ... Slot demand 72 ... Slot allocation
200: Downlink quality measuring device 202 ... Radio packet discard rate calculating device
204... Frame period signal output circuit
205 ... Timer 208 ... Error detector
210: Frame number counter 212: Received packet number counter
214 ... Number of erroneously received packets counter 216 ... Wireless packet discard rate calculator

Claims (4)

In a downlink quality measuring apparatus of a wireless communication system in which a single base station and a single or a plurality of subscriber stations are connected by a TDD method or an FDD method,
A demodulation circuit that receives a downlink radio frame including at least one fixed-length packet and outputs a reception synchronization signal for each received radio frame;
Reset for each reception synchronization signal, and outputs a reception frame period signal, and when the reception synchronization signal is not input, a frame period signal output device that outputs a self-running frame period signal by self-running,
A frame number counter that counts the received frame period signal and the free-running frame period signal and outputs the number of frames;
Counting the received synchronization signal, and a synchronous counter for outputting a count synchronization,
From the number of frames and the number of synchronizations, the number of missing frames in the downlink radio frame is calculated as follows:
(Number of frames-number of synchronizations)
The Ru calculated as a downlink quality measuring apparatus according to claim. The downlink quality measuring apparatus according to claim 1, wherein
further,
The demodulation circuit extracts and outputs a received packet from the received one radio frame,
A received packet counter that counts the extracted received packets and outputs the number of received packets;
An error detector that detects an error in the extracted received packet and outputs an error detection signal;
Counting with the error detection signal as a trigger, and an erroneously received packet number counter that outputs the number of erroneously received packets ;
Equipped with a,
From the number of missing frames, the number N of fixed-length packets included in one downlink radio frame, and the number of erroneously received packets, the number of discarded radio packets is calculated as follows:
(Number of erroneously received packets + number of missing frames x N)
The Ru calculated as a downlink quality measuring apparatus according to claim. The downlink quality measuring apparatus according to claim 2, wherein
further,
From the number of frames, the number of synchronizations, the number of received packets, the number of erroneously received packets, and the number N of fixed downlink packets in one radio frame, a radio packet discard rate is
{Number of erroneously received packets + (number of frames−number of synchronizations) × N} ÷ {number of received packets + (number of frames−number of synchronizations) × N}
A downlink quality measuring apparatus, comprising: a wireless packet discard rate calculator obtained as follows. In the downlink quality measuring apparatus according to claim 3,
further,
The downlink quality measuring apparatus, wherein an uplink of the one radio frame includes a control channel for transmitting the calculated radio packet discard rate.

Images