JP2003218770A - Radio communication system, radio base station, radio terminal and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a radio communication system in which a radio terminal in an intermittent reception station can be surely paged. <P>SOLUTION: In the radio communication system 1 comprising a base station 2 and radio terminals 3, the station 2 transmits a paging packet PPK containing paging information for the terminals 3 repeatedly a plurality of times at paging timings of prescribed intervals, and each of the terminals 3 restores from a standby state where a communication function is suspended to a communication state where the function can be exhibited synchronously with the paging timing from the station 2. By repeatedly transmitting the packet PPK a plurality of times, the terminal 3 can receive any of the plurality packets PPK even if the paging timing from the station 2 deviates from a restoring timing of the terminal 3, and thus, the terminal 3 can surely be paged. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

The present invention relates to a wireless communication system,
The present invention relates to a transmitter, a receiver, and a wireless communication method, and is suitable for application to, for example, an intermittent reception method of terminals in a wireless LAN system.

[0002]

2. Description of the Related Art Conventionally, in a mobile communication terminal such as a mobile phone, an intermittent reception method has been used in which a receiving state and a standby state are periodically repeated in a standby state in order to extend a driving time by a battery.

In such an intermittent reception method, the mobile communication terminal returns from the standby state to the reception state at regular intervals and confirms the call information from the base station. When the mobile communication terminal does not receive the call information from the base station, the mobile communication terminal returns to the standby state again, whereas when the call information is received, the mobile communication terminal returns to the transmission / reception state and notifies the base station of the return. Communication with the base station is restarted.

Since the power consumption in the standby state is much smaller than that in the communication state, the power consumption during standby is reduced by alternately repeating the communication state and the standby state by the intermittent reception method, which causes the consumption of the battery. Can be reduced and the driving time of the wireless communication terminal can be extended.

Here, in the intermittent receiving method, the reference clock is previously synchronized between the base station and the mobile communication terminal, and the mobile communication terminal returns to the receiving state at the timing when the base station transmits the call information. By doing so, the calling information can be surely transmitted and received between the base station and the mobile communication terminal.

[0006]

By the way, in recent years, a wireless LAN (Local Area Network) system for forming a small-scale computer network wirelessly has become widespread, and even in such a wireless LAN system, the above-mentioned intermittent reception method is used. It is used.

Here, for example, the error of the reference clock of the terminal in the wireless LAN standard called HiperLAN / 2 is ± 20 [ppm]. In this case, the maximum is 40 [ppm] between the wireless LAN base station and the terminal. ] Clock error occurs. If the call information transmission interval (that is, the intermittent reception waiting interval) is set to 2 [s], this clock error causes the time reference between the base station and the terminal to be 80 at maximum.
[μs] It will be shifted. In this case, the call timing of the base station and the reception timing of the terminal do not match, the terminal cannot receive the call information transmitted from the base station, and has to resynchronize with the base station. There was a problem.

The present invention has been made in consideration of the above points, and is intended to propose a wireless communication system, a transmitting device, a receiving device, and a wireless communication method capable of reliably calling a wireless terminal in an intermittent reception state. is there.

[0009]

In order to solve such a problem, according to the present invention, in a wireless communication system composed of a wireless base station and a wireless terminal, the wireless base station responds to the wireless terminal at a calling timing of a predetermined interval. The call packet including the call information is repeatedly transmitted a plurality of times, and the wireless terminal returns from the standby state in which the communication function of the wireless terminal is suspended in synchronization with the call timing of the wireless base station to the communication state in which the communication function functions. I did it.

By repeatedly transmitting the calling packet a plurality of times, the wireless terminal can receive any one of the plurality of calling packets even if the calling timing of the wireless base station and the return timing of the wireless terminal deviate from each other. The terminal can be called reliably.

In addition, the transmission time information of the call packet is written and transmitted to each of the plurality of call packets, and the time reference of the wireless terminal is corrected based on the transmission time information written in the received call packet. By doing
The time reference can be corrected each time the call packet is received, and the time reference error between the wireless base station and the wireless terminal can be minimized to reliably call the wireless terminal.

Further, the plurality of call packets are interleaved with different interleave patterns and transmitted, and the soft decision data obtained by demodulating the plurality of received call packets are combined to perform error correction processing of the call packets. By doing so, the error rate of the call packet can be improved and the wireless terminal can be called more reliably.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) Configuration of Wireless LAN System In FIG. 1, reference numeral 1 denotes a wireless LAN system according to the present invention, which includes a wireless LAN base station 2 and a plurality of wireless LAN terminals 3 having the same configuration. The base station 2 communicates with each wireless LAN terminal 3 by OFDM (Orthogonal Frequency Division) based on the HiperLAN / 2 standard.
Multiplexing) wireless data communication.

The wireless LAN base station 2 is connected to the Internet 4 via a wire, and each wireless LAN terminal 3
A personal computer 5 is connected to each. In the wireless LAN system 1, each personal computer 5 includes a wireless LAN terminal 3 and a wireless LAN.
Data communication can be performed mutually via the base station 2, and data communication can be performed with other computers, servers, etc. connected to the Internet 4.

Here, in the wireless LAN system 1,
Data is transmitted and received in a transmission unit called a frame, and each wireless LAN terminal 3 has its own RTC (Real Time Closure).
The frame cycle counter using the reference clock of ck) is synchronized with the frame cycle of the wireless LAN base station 2 and operates according to the time reference of the frame cycle counter, so that data can be transmitted and received reliably. .

Next, the structure of the wireless LAN base station 2 will be described with reference to FIG. In the wireless LAN base station 2, a CP that comprehensively controls various functions of the wireless LAN base station 2.
Bus 11 for U (Central Processing Unit) 10
RAM (Random Access Memory) 12, ROM via
(Read Only Memoly) 13, RTC 14 and wireless communication unit 15 are connected, and the CPU 10 appropriately reads various programs such as control programs stored in the ROM 13 and expands them in the RAM 12, and based on the expanded programs, the first The wireless communication unit 15 as a communication means of the above is controlled.

When the wireless communication section 15 receives the uplink wave from the wireless LAN terminal 3 via the antenna 24, the wireless communication section 15 receives the uplink wave via the antenna duplexer 16 and receives RF / I.
Input to F section 17. The reception RF / IF unit 17 performs amplification and frequency conversion processing on the received uplink wave to generate a reception signal and outputs the reception signal to the demodulator 18.

The demodulator 18 uses the OFDM for the received signal.
Network interface 2
Output to 0.

When the input received signal data is data destined for a computer on the Internet 4, the network interface 20 sends the data to the Internet 4, whereas the received signal data is sent to another wireless LAN terminal 3 When addressed, the data is output to the encoding unit 21. The network interface 20 is
When data addressed to the wireless LAN terminal 3 arrives from the Internet 4, the data is output to the encoding unit 21.

The coding unit 21 performs a convolutional coding process on the data input from the network interface 20, and outputs the data to the modulator 22. The modulator 22 subjects the input data to interleave processing and modulation processing to subcarriers to generate a transmission signal, and outputs this to the transmission RF / IF section 23.

The transmission RF / IF unit 23 amplifies and frequency-converts the input transmission signal to generate a downlink wave, and the antenna 2 is transmitted via the antenna duplexer 16.
Send from 4.

Next, the structure of the wireless LAN terminal 3 will be described with reference to FIG. In the wireless LAN terminal 3, a CPU 30 that comprehensively controls various functions of the wireless LAN terminal 3
To the RAM 32, ROM 33, R via the bus 31
The TC 34 and the wireless communication unit 35 are connected, and the CPU
Reference numeral 30 indicates an RA by appropriately reading out various programs such as a control program and an intermittent reception program stored in the ROM 33.
Expanded to M32, based on the expanded program, the second
The wireless communication unit 35 as the communication means is controlled.

When the wireless communication unit 35 receives the downlink wave from the wireless LAN base station 2 via the antenna 44, the wireless communication unit 35 receives the received downlink wave via the antenna duplexer 36.
Input to the IF unit 37. The reception RF / IF unit 37 performs amplification and frequency conversion processing on the received downlink wave to generate a reception signal and outputs the reception signal to the demodulator 38.

The demodulator 38 uses the OFDM for the received signal.
The demodulation process and the deinterleave process of the method are performed, the error correction process by the convolutional decoding is further performed in the decoding unit 39, and the data is output to the data interface 40.

The data interface 40 supplies the input received signal data to the personal computer 5 and outputs the data input from the personal computer 5 to the encoding unit 41. The encoding unit 41
The data input from the data interface 40 is subjected to convolutional coding processing and output to the modulator 42. The modulator 42 performs interleave processing and modulation processing of the OFDM method on the input data to generate a transmission signal, and outputs this to the transmission RF / IF section 43.

The transmission RF / IF unit 43 amplifies and frequency-converts the input transmission signal to generate an uplink wave, and the antenna 4 is transmitted via the antenna duplexer 36.
Send from 4.

Thus, in the wireless LAN system 1, via the wireless LAN terminal 3 and the wireless LAN base station 2,
Data communication can be performed wirelessly between the plurality of personal computers 5 or between the personal computer 5 and a computer on the Internet 4.

(2) Intermittent reception in wireless LAN system In addition to the above configuration, in the wireless LAN system 1,
When the wireless LAN terminal 3 is not performing data communication with the wireless LAN base station 2, the wireless LAN terminal 3 is consumed by executing an intermittent receiving process that periodically repeats a receiving state and a standby state according to an intermittent receiving program. It is designed to reduce power.

In this case, in the wireless LAN system 1, as shown in FIG. 4A, the wireless LAN base station 2 is set to the intermittent reception state once every 1000 frames under the control of the CPU 10 as a calling means. A paging frame including a paging channel PCH for calling a certain wireless LAN terminal 3 is transmitted. The length of one frame is 2
Since it is [ms], the paging frame transmission interval is 2
Once every [s].

In the intermittent reception state, the wireless LAN terminal 3 receives the paging packet by returning from the standby state to the reception state in synchronization with the transmission timing of a paging packet (described later) in the paging frame. When the received paging packet does not include the call for itself, the wireless LAN terminal 3 returns to the standby state again and continues the intermittent reception, whereas the paging packet includes the call for itself. If it does, the intermittent reception is terminated and the normal transmission / reception state is restored.

FIG. 4B shows the structure of the paging frame. From the head of the paging frame, the broadcast channel BCH in which the data structure information in the frame is written, the paging channel PCH, and the wireless LAN base station 2 to the wireless LAN terminal 3 are transmitted. A downlink DL for communication, an uplink UL for communication from the wireless LAN terminal 3 to the wireless LAN base station 2, and a random channel RCH for control information between the wireless LAN terminal 3 and the wireless LAN base station 2. It Incidentally, the normal frames other than the paging frame have the same configuration as the paging frame except that the downlink DL is provided immediately after the broadcast channel BCH.

As shown in FIG. 4C, the paging packet PPK is repeated eight times in the paging channel PCH. Each paging packet PPK is composed of a synchronization preamble provided at the head thereof and paging information. The length of the paging packet PPK is 3
Since it is 6 [μs], the length of the paging channel PCH is 36 [μs] × 8 = 288 [μs].

FIG. 5 shows the structure of paging information, which is Oc.
In tet2, a pointer which is the transmission time information of the paging packet PPK is written. The wireless LAN terminal 3 that has received the paging packet is able to perform reference clock synchronization with the wireless LAN base station 2 by correcting the time reference of the RTC 34 based on the value of this pointer. In Octet4 and Octet5, CRC (Cy for Octet1 to Octet3
clic Redundancy Check) code is entered.

Further, in Octet6 to Octet13,
The MAC ID of the wireless LAN terminal 3 (intermittent reception state) to be called by the wireless LAN base station 2 can be entered for eight terminals, and the received paging packet P
The wireless LAN terminal 3 having its own MAC ID entered in the paging information of the PK has its own wireless LAN base station 2
It is determined that it is called from, and the intermittent reception is terminated and the normal transmission / reception state is restored. Octet 14 and O
In ctet15, CRC codes for Octet6 to Octet13 are entered.

Here, as described above, in the paging channel PCH, the paging packet PPK is repeated eight times and transmitted (FIG. 6 (A)). Therefore, even if the reference clock of the wireless LAN terminal 3 is deviated from the reference clock of the wireless LAN base station 2, any of the eight paging packets PPK can be received.

That is, FIG. 6B shows a state in which the reference clock of the wireless LAN terminal 3 matches the reference clock of the wireless LAN base station 2, while FIG.
Is a wireless L with respect to the reference clock of the wireless LAN base station 2.
The state in which the reference clock of the AN terminal 3 is the most advanced within the allowable range (advancing by 80 [μs]), and FIG. 6D shows the state in which the reference clock of the wireless LAN terminal 3 is the most delayed within the allowable range ( 80 [μs] delay). Even in such a case, the wireless LAN terminal 3 can receive any of the eight paging packets PPK.

Further, each paging packet PPK is provided with a synchronization preamble. Therefore, the wireless LAN terminal 3 that has received the paging packet PPK
Can reliably receive the paging packet PPK by retaking frequency synchronization and timing synchronization using the synchronization preamble.

In addition to this, each paging packet PPK
As described above, since the pointer that is the transmission time information of the paging packet PPK is entered in the wireless LAN terminal 3, the wireless LAN terminal 3 that receives the paging packet PPK corrects the reference clock of the RTC 34 each time, and the wireless LAN terminal 3 corrects the wireless LAN. The reference clock can be synchronized with the base station 2, and the paging packet PPK can be reliably received.

(3) Intermittent Reception Processing of Wireless LAN Terminal Next, the intermittent reception processing in the wireless LAN terminal 3 will be described with reference to FIG.
This will be described in detail with reference to the flowchart shown in.

Wireless LAN terminal 3 as communication control means
CPU30 of the routine R according to the intermittent reception program
Enter from the start step of TI and move to step SP1.
In step SP1, the CPU 3 of the wireless LAN terminal 3
0 determines whether or not transmission / reception with the wireless LAN base station 2 is completed.

When a negative result is obtained in step SP1, this means that transmission / reception with the wireless LAN base station 2 is ongoing, and at this time, the CPU 30
Moves to step SP13 and continues the normal transmission / reception operation. On the other hand, when a positive result is obtained in step SP1, this means that transmission / reception with the wireless LAN base station 2 is completed, and at this time, the CPU 30
Moves to step SP2.

In step SP2, the CPU 30 determines whether or not a predetermined waiting time has elapsed after the end of transmission / reception.

When a negative result is obtained in step SP2, this means that a predetermined waiting time has not yet elapsed after the end of transmission / reception with the wireless LAN base station 2, and the CPU 30 at this time. Return to step SP1. On the other hand, when a positive result is obtained in step SP2, this means that a predetermined waiting time has elapsed after the end of transmission / reception, and at this time, the CPU 30 shifts to step SP3 and shifts to the standby state. After notifying the wireless LAN base station 2, step SP4
Move on to.

In step SP4, the CPU 30 detects the number of frames after which the next paging from the wireless LAN base station 2 will be performed, sets this return timing (frame) in the return timing counter (not shown), and then, The circuits other than the return timing counter are shifted to the standby state in which the circuits are stopped, and the process proceeds to the next step SP5.

In step SP5, the CPU 30 determines whether the counter value of the return timing counter is one frame before the return timing (999 frames when the return timing is 1000 frames). When a negative result is obtained in step SP5, this means that it is not yet one frame before the return timing, and at this time, the CPU 30 returns to step SP5. On the other hand, when a positive result is obtained in step SP5, this means that the current time is one frame before the return timing, and at this time, the CPU 30 moves to step SP6.

In step SP6, the CPU 30 sends and receives the RF / IF system 2 in the wireless LAN terminal 3.
The analog circuits such as 3, 17 and the modulator 22 and the demodulator 28 are turned on and activated. This is because these circuits have a slower rising edge than digital circuits, so that the paging packet PPK can be reliably received by starting the circuits before the paging timing.

At the next step SP7, the CPU 30
Determines whether the counter value of the return timing counter has reached the return timing. When a negative result is obtained in step SP7, this means that the return timing has not been reached yet, and at this time, the CPU 30 returns to step SP7. On the other hand, when a positive result is obtained in step SP5, this means that the return timing has been reached, at which time the CPU 30 moves to step SP8 and activates all circuits of the wireless LAN terminal 3 to receive. It returns to the state and waits for the paging packet PPK.

Then, in step SP9, the CPU3
0 determines whether or not the paging packet PPK has been received.

If a negative result is obtained in step SP9, this means that the paging packet PPK could not be received. At this time, the CPU 30 proceeds to step SP14 and uses the synchronization preamble to perform frequency synchronization and timing. After resynchronization, the process returns to step SP9 and waits for the paging packet PPK again.

On the other hand, if a positive result is obtained in step SP9, this means that the paging packet P
It indicates that the PK has been successfully received. At this time, CP
The U30 moves to step SP10, corrects the time reference of the RTC 34 based on the pointer of the received paging packet PPK, and moves to the next step SP11.

At step SP11, the CPU 30
The paging information of the received paging packet PPK is referred to, and it is determined whether or not the paging packet PPK is a call to itself.

If a negative result is obtained in step SP11, this means that the MAC address of the self is included in the paging information.
ID is not entered, and the paging packet P concerned
This means that PK is not a call to itself, and at this time, the CPU 30 returns to step SP4 and shifts to the standby state again.

On the other hand, when a positive result is obtained in step SP11, this means that the MAC ID of the self is written in the paging information, and the paging packet PPK is a call to itself. At this time, the CPU 30 moves to step SP12.

At step SP12, the CPU 30
After transmitting the paging acknowledge signal indicating that the paging for itself has been confirmed to the wireless LAN base station 2, the process proceeds to step SP13, the normal transmission / reception state is restored, and the communication with the wireless LAN base station 2 is started, and step SP1 Return to.

In the above configuration, the wireless LAN terminal 3 of the wireless LAN system 1 performs the intermittent reception process which periodically repeats the receiving state and the standby state when not performing data communication with the wireless LAN base station 2. By
The power consumption of the wireless LAN terminal 3 is reduced.

On the other hand, the wireless LAN base station 2
A paging packet PP for calling the wireless LAN terminal 3 in the intermittent reception state once every 00 frames.
Send a paging frame containing K. In the discontinuous reception state, the wireless LAN terminal 3 receives the paging packet PP
By returning from the standby state to the receiving state in synchronization with the transmission timing of K, the paging packet P
Receive PK.

At this time, the wireless LAN base station 2 repeatedly transmits the paging packet PPK eight times. As a result, even if the reference clock of the wireless LAN terminal 3 deviates from the reference clock of the wireless LAN base station 2, the wireless L
The AN terminal 3 can receive any of the eight paging packets PPK.

Further, the wireless LAN base station 2 attaches a synchronization preamble to each paging packet PPK and transmits it. Thereby, the wireless LAN terminal 3 can surely receive the paging packet PPK by re-taking the frequency synchronization and the timing synchronization using the synchronization preamble.

Even if an error occurs in the received paging packet PPK due to a change in the radio wave propagation environment such as fading, the paging packet PPK is repeatedly transmitted eight times, and each paging packet PPK has a synchronization preamble. Since it is attached, the probability that any paging packet PPK can be received without error can be improved.

In addition to this, each paging packet PPK
Since the pointer which is the transmission time information of the paging packet PPK is entered in the wireless LAN terminal 3, the wireless LAN terminal 3 receiving the paging packet PPK receives R each time.
The time reference of the TC 34 can be corrected to perform reference clock synchronization with the wireless LAN base station 2, and thus the paging packet PPK can be reliably received.

Since the wireless LAN system 1 repeatedly transmits the paging packet PPK, the amount of data that can be transmitted is reduced accordingly. Specifically, every 1000 frames (2 [s]), 36 [μs] × 8 =
Since the paging packet PPK is transmitted for 288 [μs], the amount of data that can be transmitted is 288.
Decrease by [μs] / 2 [s] = 0.144%. However, if the error rate can be improved by repeatedly transmitting the paging packet PPK, it is possible to improve the transmission data amount as a whole.

According to the above configuration, the wireless LAN base station 2
By repeatedly transmitting the paging packet PPK a plurality of times, even if the reference clock of the wireless LAN terminal 3 is deviated from the reference clock of the wireless LAN base station 2, the wireless LAN terminal 3 receives eight paging packets P.
It is possible to reliably receive any of the PKs.

Further, by transmitting each paging packet PPK with a synchronization preamble attached,
The wireless LAN terminal 3 can regain frequency synchronization and timing synchronization by using the synchronization preamble, and thus can reliably receive the paging packet PPK.

Further, the wireless LAN terminal 3 is filled with a pointer which is the transmission time information of the paging packet PPK and is transmitted to each paging packet PPK.
RTC3 each time the paging packet PPK is received
4 can be corrected to perform reference clock synchronization with the wireless LAN base station 2, and thus the paging packet PPK can be reliably received.

(4) Other Embodiments In the above embodiment, the wireless LAN base station 2 repeatedly transmits the paging packet PPK eight times so that the paging packet PPK can be reliably received. In addition to this, Hybrid AR
It is possible to further reduce the reception error of the paging packet PPK by applying the technique used in Q (Automatic Repeat Request).

For example, as shown in FIG. 8, in the modulator 22 of the wireless LAN base station 2, first and second interleavers 50A and 50A having different interleaving patterns (OFDM subcarrier allocation and frequency hopping patterns) are provided. 50B is provided.

The modulator 22 uses only the second interleaver 50B when transmitting normal data, and performs interleaving with a single interleave pattern, whereas it transmits the paging packet PPK. , First
And second interleavers 50A and 50B are used alternately to perform interleaving. As a result, the eight paging packets PPK are interleaved with different interleaving patterns alternately, and then modulated by the modulator 51 and transmitted.

On the other hand, as shown in FIG. 9, the wireless LAN terminal 3
In the demodulator 38, the first and second deinterleavers 53A and 53B are provided after the demodulation unit 52. The first and second deinterleavers 53A and 53B are
The wireless LAN base station 2 has deinterleave patterns corresponding to the interleave patterns of the first and second interleavers 50A and 50B, respectively.

The demodulator 38 uses only the second deinterleaver 53B when receiving normal data, and performs deinterleaving with a single deinterleave pattern. The demodulator 38 then uses the second deinterleaver 53.
The output data (soft decision data) of B is output to the decoding unit 39 (FIG. 3) via the switch 56. The decoding unit 39 performs error correction processing on this soft decision data.

On the other hand, when receiving the paging packet PPK, the demodulator 38 interleaves by alternately using the first and second deinterleavers 53A and 53B. The output of the first deinterleaver 53A is
After being delayed by one packet by the delay device 54, the data is input to the combiner 55. On the other hand, the output of the second deinterleaver 53B is directly input to the combiner 55.

As a result, the paging packet PPK deinterleaved with the first deinterleave pattern and the next paging packet PPK deinterleaved with the second deinterleave pattern are simultaneously input to the combiner 55. . The outputs from the first and second deinterleavers 53A and 53B are output as soft decision data, respectively. The combiner 55 combines the soft-decision data deinterleaved with the first deinterleave pattern and the soft-decision data deinterleaved with the second deinterleave pattern, and switches the combined soft-decision data with the switch 56. To the decoding unit 39 via. The decoding unit 56 performs error correction processing on the combined soft decision data.

Here, when frequency-selective fading occurs in the radio wave propagation environment, subcarriers at the same position in each paging packet PPK are affected by fading to almost the same extent, and the S / N ratio is increased. It deteriorates and the error rate deteriorates. However, by performing interleaving and deinterleaving by alternately using two different patterns, it is possible to disperse the influence of fading and improve the error rate.

For example, the data of the paging packet PPK shown in FIG. 10A is interleaved by the first interleaver 50A as shown in FIG. 10B, is assigned to the subcarriers, and is transmitted. 50B interleaves as shown in FIG. 10C, allocates to subcarriers, and transmits. At this time, it is assumed that the S / N ratio of some subcarriers is lowered due to the frequency selective fading in the radio wave propagation environment.

In this case, two paging packets PP
The same subcarrier in K causes the error rate to deteriorate. However, since the two paging packets PPK have different interleaving patterns, it is highly possible that the data whose error rate deteriorates in one packet does not deteriorate in the other packet. Therefore, by combining the soft-decision data after deinterleaving, the paging packet P as a whole can be obtained.
The error rate of PK can be improved, and the paging packet PPK can be received more reliably.

In the above-mentioned embodiment, the wireless L
The case where the present invention is applied to the intermittent reception in the AN system has been described, but the present invention is not limited to this, and the present invention may be applied to the intermittent reception in various other wireless systems.

[0077]

As described above, according to the present invention, the radio base station repeatedly transmits the call packet including the call information for the radio terminal at a call timing of a predetermined interval, and the radio terminal is the radio base station. Since the wireless terminal communication function is restored from the standby state in which the communication function of the wireless terminal is suspended in synchronization with the call timing of the wireless terminal, the calling timing of the wireless base station and the recovery timing of the wireless terminal are deviated. Even if it does, the wireless terminal can receive any one of the plurality of call packets, and thus a wireless communication system that can call the wireless terminal reliably can be realized.

Further, the transmission time information of the calling packet is written in each of the plurality of calling packets and transmitted, and the time reference of the wireless terminal is corrected based on the transmission time information written in the received calling packet. By doing
The time reference can be corrected each time the call packet is received, and the wireless terminal can be reliably called by minimizing the reference clock error between the wireless base station and the wireless terminal.

Furthermore, interleaving processing is performed with different interleaving patterns for each of a plurality of call packets, the plurality of call packets are transmitted, and the soft decision data obtained by demodulating the plurality of received call packets are combined to perform error correction processing of the call packets. By doing so, the error rate of the call packet can be improved and the wireless terminal can be called more reliably.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a wireless LAN system according to the present invention.

FIG. 2 is a block diagram showing a configuration of a wireless LAN base station.

FIG. 3 is a block diagram showing a configuration of a wireless LAN terminal.

FIG. 4 is a schematic diagram showing a configuration of a paging frame.

FIG. 5 is a schematic diagram showing a configuration of paging information.

FIG. 6 is a timing chart showing clock error and packet reception timing.

FIG. 7 is a flowchart showing an intermittent reception process.

FIG. 8 is a block diagram showing a configuration of a modulator of another embodiment.

FIG. 9 is a block diagram showing the configuration of a demodulator of another embodiment.

FIG. 10 is a schematic diagram showing interleaving and S / N ratio deterioration.

[Explanation of symbols]

1 ... Wireless LAN system, 2 ... Wireless LAN base station,
3 ... Wireless LAN terminal, 4 ... Internet, 5 ...
Personal computer, 10, 30 ... CPU, 1
1, 31 ... Bus, 12, 32 ... RAM, 13, 33
...... ROM, 14, 34 ...... RTC, 15, 35 ...... Communication section, 16, 36 ...... Antenna duplexer, 17, 37 ......
Reception RF / IF, 18, 38 ... Demodulator, 19, 39 ...
… Decoding unit, 20 …… Network interface, 1
9, 39 ... Decoding section, 19, 39 ... Decoding section, 21, 4
1 ... Encoding unit, 22, 42 ... Modulator, 23, 43 ...
… Transmission RF / IF, 24,44 …… Antenna, 40 ……
Network interface, 50A, 50B ... Interleaver, 51 ... Modulation section, 52 ... Demodulation section, 53
A, 53B ... Deinterleaver, 54 ... Delay device.

Claims (18)

[Claims] 1. A wireless communication system comprising a wireless base station and a wireless terminal, wherein the wireless base station has a first communication means for wirelessly communicating with the wireless terminal and a call timing at a predetermined interval. And a calling unit that repeatedly transmits a calling packet including calling information for the wireless terminal through the first communication unit, the wireless terminal performing wireless communication with the wireless base station. Communication for controlling the second communication means and the second communication means so as to return from a standby state in which the communication function of the wireless terminal is suspended to a communication state in which the communication function functions, in synchronization with the call timing. A wireless communication system comprising: a control unit. 2. The wireless communication system according to claim 1, wherein the calling means adds a preamble for synchronization of the calling packet to each of the plurality of calling packets and transmits the packet. 3. The calling means writes transmission time information of the calling packet in each of the plurality of calling packets and transmits the calling packet, and the communication control means writes the transmission described in the received calling packet. The wireless communication system according to claim 1, wherein the time reference of the wireless terminal is corrected based on time information. 4. The time reference between the radio base station and the radio terminal, wherein the call means is determined by a transmission interval of the call packet and a maximum reference clock error of the radio terminal allowed in the radio communication system. For longer than the gap
The wireless communication system according to claim 1, wherein the call packet is repeatedly transmitted. 5. The wireless communication system according to claim 1, wherein the first communication means performs interleave processing with different interleave patterns for each of the plurality of call packets and transmits the interleaved packets. 6. The method according to claim 5, wherein the second communication means synthesizes the soft-decision data obtained by demodulating the plurality of received call packets and performs error correction processing on the call packets. The described wireless communication system. 7. A wireless base station that wirelessly communicates with a predetermined wireless terminal, communication means that wirelessly communicates with the wireless terminal, and call information for the wireless terminal at a call timing of a predetermined interval. And a calling means for repeatedly sending a calling packet including a plurality of times via the communication means. 8. The radio base station according to claim 7, wherein the calling means adds a preamble for synchronization of the calling packet to each of the plurality of calling packets and transmits the packet. 9. The time reference between the radio base station and the radio terminal, wherein the call means is determined by a transmission interval of the call packet and a maximum reference clock error of the radio terminal allowed in the radio communication system. For longer than the gap
The radio base station according to claim 7, wherein the call packet is repeatedly transmitted. 10. The radio base station according to claim 7, wherein the communication means performs interleaving processing with different interleaving patterns for each of the plurality of calling packets and transmits the interleaved packets. 11. A wireless terminal for performing wireless communication with a predetermined wireless base station, the communication means for performing wireless communication with the wireless base station, and the communication means for controlling the communication means from the wireless base station. Communication control means for returning from a standby state in which the communication function of the wireless terminal is suspended to a communication state in which the communication function is functioning, in synchronization with the transmission timing of a call packet including call information to be transmitted to the wireless terminal. A wireless terminal characterized by comprising. 12. The communication control means corrects the time reference of the wireless terminal based on the transmission time information of the call packet entered in the received call packet. Wireless terminal. 13. A wireless communication method for a wireless communication system comprising a wireless base station and a wireless terminal, wherein a calling packet including calling information for the wireless terminal is repeated a plurality of times from the wireless base station at calling timings at predetermined intervals. And a intermittent communication step of returning from a standby state in which the communication function of the wireless terminal is suspended to a communication state in which the communication function works, in synchronization with the call timing. Wireless communication method. 14. For each of the plurality of call packets,
14. The wireless communication method according to claim 13, wherein a synchronization preamble of the calling packet is added, and reception synchronization processing of the wireless terminal is performed based on the synchronization preamble. 15. For each of the plurality of calling packets,
14. The wireless communication method according to claim 13, wherein transmission time information of the call packet is entered, and the time reference of the wireless terminal is corrected based on the transmission time information entered in the received call packet. . 16. A deviation of a time reference between the radio base station and the radio terminal, which is determined by a transmission interval of the calling packet and a maximum reference clock error of the radio terminal allowed in the radio communication system. 14. The wireless communication method according to claim 13, wherein the call packet is repeatedly transmitted for a long time. 17. The wireless communication method according to claim 13, wherein the plurality of call packets are subjected to interleaving processing with different interleaving patterns and then transmitted. 18. The wireless communication method according to claim 17, wherein soft-decision data obtained by demodulating a plurality of received call packets is combined to perform error correction processing of the call packets.