JP2001345752A - Radio access system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sleep processing part for effective power saving in a radio terminal station. SOLUTION: The sleep processing part 103 is equipped with a propagation environment estimating part 141 for estimating the propagation environment of the radio terminal station, and a sleep frame operating part 142 for calculating the number of sleep frames in the case of battery saving, on the basis of the results estimated by the estimating part 141. The processing part 103 estimates the propagation environment of the radio terminal station to a radio base station of radio connection, and calculates the number of sleep frames in the case of battery saving, on the basis of the estimated results.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio access system comprising a radio base station and a radio terminal station which transmits and receives information to and from the radio base station, and more particularly to a radio access system for battery saving in the radio terminal station. It relates to improvement of a sleep processing unit.

[0002]

2. Description of the Related Art At present, equipment terminals such as personal computers have become widespread, LANs have been constructed in companies and the like, data exchange between personal computers, shared use of equipment such as printers, and access to external networks have been performed. .

In networking such as a LAN, connections between servers, personal computers, and other devices are made by wire. For this reason, rewiring work must be performed every time the layout is changed, such as when the arrangement of personal computers is moved. The same applies to a notebook personal computer with high mobility. When the notebook personal computer is connected to an existing LAN and used, it can be used only at a place where a wiring connection port is provided.

[0004] As a method of wireless connection to a network or the like, a method of performing connection via a mobile phone or a PHS has been widely used. This allows access to the network within the area of the wireless network even while moving. The transmission capacity of the portable telephone and the PHS by wireless connection is 64 [kbps] at present. For this reason, it can be used comfortably for sending and receiving Internet mail and accessing homepages with relatively small data capacity. However, in the future, it is possible to use large-volume data such as moving images, which are expected to increase in use as content. It is hard to say that it is suitable for access.

[0005] For this reason, a wireless access system capable of accessing a larger amount of data is required, and IEEE8080 is required.
2.11 (USA), ATM Forum (USA), ETSI-BRAN
(Europe), MMAC (Japan), etc.

[0006] Regarding the radio access system studied in the MMAC, using the frequency bands of 5 [GHz] and 25 [GHz], outdoor 20 [Mbps] or more (1 user maximum 10 [Mbps]), indoor The goal is an information transmission speed of 156 [Mbps]. Of these, in the 5 [GHz] band, the OFDM method is used as a wireless method, and a transmission rate of 20 [Mbps] or more is targeted. Hereinafter, the 5 [GHz] band of the MMAC will be described.

Transmission and reception of data between a radio base station (hereinafter, AP) and a radio terminal station (hereinafter, MT) are performed using a 2 [ms] MAC.
(Media Access Control) This is performed for each frame. 1MA
The C frame has six physical channels (BCH, FCH,
ACH, SCH, LCH, RCH)
BCH is a channel having information such as the ID of the AP to which the MAC frame belongs, and FCH is M
A channel describing the structure of an AC frame.
CH is a channel that describes ACK information for RCH, SCH is a channel for data transmission other than BCH, FCH, ACH, and RCH, and is a channel for short size. LCH is a channel other than BCH, FCH, ACH, and RCH. The channel for data transmission is a channel for a long size, and the RCH is a channel for random access.
One MAC frame is data transmission from BCH, FCH, ACH, AP to MT, Down-Link composed of SCH and LCH, data transmission from MT to AP, and composed of SCH and LCH Up-Link, RCH
(FIG. 2). The bandwidth allocation for data transmission and reception between the AP and each MT is described in FCH,
Each MT transmits and receives data based on the FCH.

When transmitting the BCH, a preamble A field, B field, C
The three signals of the field are transmitted in an added form (FIG. 3). The signal in the order of the preamble A field and the B field is added only to the head of the BCH at the head of the frame. Therefore, the receiving side can detect the head of the MAC frame by detecting the preamble A field and the B field.

The transmission / reception operation in the AP and MT will be described with reference to FIGS. Ethernet (registered trademark) network 8
When data that needs to be transmitted is received from the CL, a data format conversion is performed in a CL unit (convergence layer data conversion unit) 5 and the data is stored in the transmission buffer 1. The DLC unit (data link control unit) 2 adds a sequence number for selective retransmission processing (Selective Repeat ARQ), and the scheduling data buffer unit 9
The encoding process according to the encoding mode described in (1) is performed by the transmission PHY unit 3 and transmitted via the RF unit 7 and the antenna unit 4. The coded data received via the antenna unit 4 and the RF unit 7 is subjected to decoding processing corresponding to the coding mode described in the scheduling data buffer unit 9 by the reception P.
This is performed by the HY unit 12, the error-free data is accumulated in the reception buffer unit 13 in the reception DLC unit 10, and the ACK /
The NAK information transmission request is sent to the MAC unit 15. The data stored in the reception buffer unit 13 is format-converted by the CL unit 5 and transmitted to the Ethernet network 8.

[0010] In the MT 202, a bandwidth allocation request for data transmission from the MT 202 is sent to the AP 201. In the AP 201, the scheduling unit 14 allocates a bandwidth required for data transmission from the own AP 201 to each MT and a bandwidth for each MAC frame based on a bandwidth allocation request from each MT. Based information is described in the scheduling data buffer unit 9 and transmitted to the MT using the FCH.
The MT 202 writes, in the scheduling data buffer unit 9, information related to its own MT among the scheduling information described in the received FCH. AP and MT are transmission / reception timing in transmission / reception, and PHY units 3 and 1
2 is performed based on the scheduling information described in the scheduling data buffer unit 9.

[0011]

In a mobile station (MT), since it is a mobile terminal, it is required to reduce the size and weight of the apparatus and to prolong its use time. Usually, access to a network such as Ethernet from a PC is
The data does not always flow, but a huge amount of data flows locally when accessed. Therefore, the access time to the network is shorter than the use time of the personal computer. For this reason, reducing the power consumption of the MT in a state where the network access is not being performed (hereinafter, a standby state) leads to a longer use time of the MT.

Usually, during communication between the MT and the AP, a necessary circuit voltage is supplied. On the other hand, in the process of reducing power consumption in the standby state (hereinafter referred to as battery saving), the supply of power to unnecessary circuits is stopped (sleep state), and a period determined between APs (the number of sleep frames) Is supplied only when it is checked whether there is an access request from the AP (sleep release check processing). This reduces power consumption during the standby state.

The process in battery saving will be described with reference to FIG. If it is determined that the standby state continues and the state shifts to the sleep state, the MAC unit 6 issues a sleep request,
And the number of requested sleep frames is transmitted to the AP via the transmission PHY unit 3. Upon receiving the sleep permission signal including the number of permitted sleep frames from the AP and the number of frames for synchronization adjustment, the MAC unit 6 sets a value corresponding to the number of frames for synchronization adjustment in the timer count calculation unit 107, The operation clock and the timer count to be used are calculated from the set number of frames by the timer count calculation unit 107, set in the sleep timer unit 106, and temporarily enter the sleep state. The sleep timer unit 106 operates at the set operation clock, and sends a processing request to the sleep operation processing unit 103 after the set timer count.
The sleep operation processing unit 103 starts sleep release check processing, and the frame synchronization detection unit 109 searches for the head of the frame based on the preamble A and B fields located at the head of the frame. When the frame synchronization detecting section 109 detects the head of the frame, the decoding processing section 108 decodes the subsequently received BCH data. The BCH is sent to the BCH reception buffer unit 102, and the BCH data analysis unit 101 determines from the identifier and frame number of the AP described in the BCH whether or not the frame is the target frame of the target AP. If they do not match, the frame synchronization detection unit 109 continues to detect the head of the frame. If they match, the mobile station checks the presence / absence flag of the band allocation to the sleeping MT described in the BCH.
Send to Part 6. The MAC unit 6 sets the reception of the FCH in the transmission / reception schedule data buffer unit 9. When receiving the FCH, the received FCH is stored in the FCH reception buffer unit 105.
And the received data determination unit 104 determines whether or not there is a band allocation related to the own MT. The received data determination unit 104 sends the determination result to the sleep operation processing unit 103, and the sleep operation processing unit 103
Send to C section 6 to release sleep. If the received data determination unit 104 determines that there is no allocation,
If the H data analysis unit 101 determines that there is no allocation, the sleep operation processing unit 103 continues the sleep process, sets the number of permitted sleep frames in the timer count calculation unit 107, and calculates the timer count calculation unit 107. Based on the result, the sleep timer unit 106 is activated and enters a sleep state. When the sleep from the MT is released, that is, when there is information to be transmitted from the MT to the AP, the MAC unit 6 releases the sleep and transmits a band allocation request for information transmission to the AP using the RCH. Upon receiving the bandwidth allocation request, the mobile station recognizes that the MT has been released from sleep.

As a result, wasteful power consumption in the standby state can be reduced, and as a result, the use time can be prolonged. Furthermore, the power consumption and the clock supply circuit can be minimized according to the processing state such as the sleep state, the frame synchronization detection, and the BCH data analysis processing, so that the overall power consumption can be reduced. Becomes

[0015] The number of sleep frames is determined by exchanging sleep settings between the MT and the AP in order for the MT to transition to the sleep state. Normally, the MT is used without changing the number of sleep frames exchanged with the AP when shifting to the sleep state.

However, the MT is a mobile terminal and does not always exist at a fixed position. Therefore, MT
Is present near an AP with a good propagation environment, and even if a long sleep frame number is used, it is unlikely that the transmission frame from the AP will fail to be received. If a start request is issued, it can be started immediately. However, if there is almost no start request from the AP, power is wasted for the sleep cancel check process, and consequently the MT is consumed.
To shorten the usage time.

On the other hand, when MT has poor propagation environment, for example, AP
In the case where the number of sleep frames set is long in the case where there is a high possibility that reception of a transmission frame from the AP is unsuccessful near the boundary of the service area, power consumption can be reduced. If there is an activation request from the AP, there is a high possibility that reception will fail due to poor propagation environment, the time until the next frame for performing the sleep release check processing after the reception failure is long, and in some cases, the There is a possibility that the activation request ends first and the call cannot be received.
An object of the present invention is to reduce power consumption and ensure responsiveness by changing the number of sleep frames according to a propagation environment in a wireless access system.

[0018]

According to a first aspect of the present invention, there is provided a radio base station for transmitting and receiving information, and a radio terminal station for transmitting and receiving information to and from the radio base station by radio. In the wireless access system, the wireless terminal station has a sleep processing unit that performs power control during battery saving in a standby state, the sleep processing unit includes a propagation environment estimation unit that estimates a propagation environment of the wireless terminal station. A sleep frame calculating unit that calculates the number of sleep frames during battery saving based on the estimation result by the propagation environment estimating unit, and is configured to reduce power consumption during battery saving. .

According to a second aspect of the present invention, in the first aspect of the present invention, the sleep processing unit increases the number of sleep frames when the propagation environment is good, and decreases the number of sleep frames when the propagation environment is bad. The gist of the present invention is that a sleep frame operation unit is provided.

According to a third aspect of the present invention, in the first aspect, the sleep processing unit includes a propagation environment estimating unit for estimating based on a reception level of a signal transmitted from the radio base station.

According to a fourth aspect of the present invention, in the third aspect, the sleep processing unit calculates the number of sleep frames to increase the number of sleep frames when the reception level is high and to decrease the number of sleep frames when the reception level is low. The gist is that the unit is provided.

According to a fifth aspect of the present invention, in the first aspect, the sleep processing unit includes a propagation environment estimating unit for estimating based on a reception error rate of a signal transmitted from the radio base station. .

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the sleep processing section increases the number of sleep frames when the reception error rate is high, and decreases the number of sleep frames when the reception error rate is low. The gist is that a number calculation unit is provided.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the propagation environment estimating section includes N propagation environments (N is 1 or more).
And the number of determinations M (A, B) (M (A, B) is 1 or more) for determining the transition of the level according to the level (A) of the transition source and the level (B) of the transition destination. When the number of determinations of the set level transition is equal to or more than the number of determinations M (A, B), a propagation environment estimating unit for estimating the propagation environment by changing the level output as the estimation result is provided. Is the gist.

According to an eighth aspect of the present invention, in the first aspect of the invention, the sleep processing unit calculates the first sleep frame number calculated by the sleep frame calculating unit and transmitted to the wireless base station from the wireless base station. When the received second sleep frame number is large, the first sleep frame number is adopted as the third sleep frame number actually used by the wireless terminal station, and occurrence of frame synchronization loss due to a reception error is suppressed. The gist is that a sleep processing unit is provided.

A ninth aspect of the present invention is based on the first aspect, wherein the propagation environment estimating section estimates the propagation environment based on a reception level and a reception error rate of a signal transmitted from the radio base station. I do.

According to a tenth aspect of the present invention, in a wireless access system including a wireless base station for transmitting and receiving information and a wireless terminal station for transmitting and receiving information to and from the wireless base station, the wireless terminal station is in a standby state. A sleep processing unit for performing power control during battery saving in the state, wherein the sleep processing unit calculates a sleep frame during battery saving calculated in accordance with an estimated propagation environment between the wireless terminal station and the wireless base station. Has a table of numbers,
The gist of the present invention is to reduce the power consumption during battery saving.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is used for the location which shows the same structure. FIG. 1 is a basic configuration diagram of a sleep processing unit according to an embodiment of the present invention. When the standby state is continued and it is determined that the state shifts to the sleep state, M
The AC unit 6 sends the sleep request and the number of requested sleep frames to the AP via the transmission PHY unit 3. AP
When the MAC unit 6 receives the sleep permission signal including the number of allowed sleep frames and the number of frames for synchronization adjustment, the MAC unit 6 sets a value corresponding to the number of frames for synchronization adjustment in the timer count calculation unit 107, and An operation clock to be used and a timer count are calculated from the set number of frames by the timer count calculation unit 107, and set in the sleep timer unit 106 to temporarily enter a sleep state. The sleep timer unit 106 operates at the set operation clock, and sends a processing request to the sleep operation processing unit 103 after the set timer count. Sleep operation processing unit 103
Starts a sleep release check process, and the frame synchronization detection unit 109 detects that the preamble A
The head of the frame is searched based on the field and the B field. When the frame synchronization detecting section 109 detects the head of the frame, the decoding processing section 108 decodes the subsequently received BCH data. The BCH is sent to a BCH reception buffer unit 102, and a BCH data analysis unit 101
H from the AP identifier and frame number described in H
It is determined whether the received frame is the target frame of the target AP, and if they do not match, the frame synchronization detection unit 109 continues to detect the head of the frame. If matched, BCH
And checks whether or not there is a band allocation flag for the MT during sleep described in (1). MAC unit 6
Sets the reception of the FCH in the transmission / reception schedule data buffer unit 9. If FCH is received, the received FC
H is sent to the FCH reception buffer unit 105, and the reception data judgment unit 104 judges whether there is a band assignment related to the own MT. The reception data determination unit 104 sends the determination result to the sleep operation processing unit 103, and the sleep operation processing unit 1
03 sends a sleep release request to the MAC section 6 to release the sleep. When the reception data determination unit 104 determines that there is no allocation, or when the BCH data analysis unit 101 determines that there is no allocation, the sleep operation processing unit 103
Performs continuation of sleep processing, and counts the timer count.
The number of permitted sleep frames is set to 107, and the sleep timer unit 106 is activated based on the calculation result of the timer count calculation unit 107 to enter a sleep state. When the sleep is released from the MT, that is, when there is information to be transmitted from the MT to the AP, the MAC unit 6 releases the sleep and transmits a band allocation request for information transmission to the AP using the RCH. Receives the bandwidth allocation request,
The sleep release of the MT is recognized.

The sleep timer operation processing unit 103 includes a propagation environment estimation unit 141, a sleep frame calculation unit 142, and a sleep control unit 143. The propagation environment estimation unit 141
The propagation environment is estimated based on variable values (for example, reception level, error rate, etc.) for estimation from the C unit 6.
The sleep frame calculation unit 142 calculates the number of sleep frames based on the estimation result. The calculated number of sleep frames is sent to the MAC unit 6 via the sleep control unit 143, and is sent to the AP together with the sleep request.
In the sleep state, when the sleep control unit 143 determines from the calculation results of the propagation environment estimation unit 141 and the sleep frame calculation unit 142 that the propagation environment has transitioned, the sleep control unit 143 allocates a band to the AP to change the number of sleep frames. A request is transmitted, and a sleep request is transmitted to the AP together with the calculated number of sleep frames. The propagation environment estimation unit 141,
From the variable value for estimation from the MAC unit 6, the current MT
Is estimated. N propagation environments (N is 1 or more)
And the number of times that the current estimation result level (B) is determined to have shifted from the previous level (A) is M (A,
B) When the number of times (M (A, B) is 1 or more) occurs, the current level is shifted (A → B). Number of determinations M
(A, B) differs depending on the level from the transfer source (A) to the transfer destination (B).

When the propagation environment estimation unit 141 estimates that the propagation environment is bad, the number of sleep frames received from the AP is calculated by the sleep frame calculation unit 142.
If the number is larger than the number of sleep frames calculated by the
As the number of sleep frames transmitted to 07, the number of sleep frames calculated by the sleep frame calculation unit 142 is adopted. Thus, in a case where the transmission signal of the AP fails to be received due to a poor propagation environment, it is possible to suppress the occurrence of frame loss due to an error by attempting to receive a frame that is originally not intended.

FIG. 7 is an example of a graph showing the relationship between the estimated value of the propagation environment and the number of sleep frames in the sleep processing unit according to one embodiment of the present invention. The vertical axis is the number of sleep frames, and the direction of the arrow is the direction in which the number of sleep frames increases. The horizontal axis is the propagation environment, and the direction of the arrow is the direction in which the propagation environment deteriorates. The solid line indicates the number of sleep frames used in the present invention, and the thick broken line indicates the conventional setting of the number of sleep frames. The level of the propagation environment is divided into level A, level B, and level C in descending order. Referring to FIG. In the conventional setting of the number of sleep frames, the number of sleep frames does not change even if the propagation environment changes. On the other hand, in the setting of the number of sleep frames according to the present invention, the number of sleep frames is divided into level A, level B, and level C based on the propagation environment, and when the propagation environment is good (level A), the number of sleep frames is increased. ,
The power consumption can be reduced, and the number of sleep frames is reduced when the propagation environment is poor (level C). Since the number of frames up to the frame to be processed is small, it is possible to cope in a short time.

Assuming that the number of determinations M (C, B) of the change from level C to level B is 3 and the number of determinations M (B, C) of the change from level B to level C is 1, If you move from B to level C in a poor propagation environment,
Since the number of determinations M (B, C) is 1, the number of sleep frames can be changed immediately, responsiveness can be ensured, and the occurrence of loss of synchronization due to an error can be suppressed. Further, when the level C and the level B are switched back and forth, the number of determinations M (C, B) is 3, so that the number of sleep frames is not updated, and unnecessary power consumption is prevented. Becomes possible.

A variable for transition determination to the propagation environment estimating unit 141 is input from the MAC unit 6.
It may be from another part. For example, when the variable is the reception level, the reception level of the RF unit may be directly input. Also, the sleep frame calculation unit 142
Is a table L of the number of sleeve frames set corresponding to the levels of the N variable values in the propagation environment estimation unit 141.
It may be a UT (lookup table).

As described above, according to the present invention, the number of sleep frames is changed in accordance with the propagation environment to reduce power consumption in a favorable propagation environment and ensure responsiveness in a poor propagation environment. It is possible to do. In addition, it is possible to suppress the occurrence of loss of synchronization due to an error.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a sleep processing unit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a frame structure of MMAC.

FIG. 3 is a configuration diagram of a BCH.

FIG. 4 is a schematic diagram of a configuration of a wireless base station (AP).

FIG. 5 is a schematic diagram of a configuration of a wireless terminal station (MT).

FIG. 6 is a basic configuration diagram of a conventional sleep processing unit.

FIG. 7 is an example of a graph of the estimated value of the propagation environment-the number of sleep frames in the sleep processing unit according to the embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 1 transmission buffer unit 2 transmission DLC unit 3 transmission PHY unit 4 antenna 5 CL unit 6 MAC unit 7 RF unit 8 Ethernet 9 transmission / reception schedule data buffer unit 10 reception DLC unit 11 sleep processing unit 12 reception PHY unit 13 reception buffer unit 14 scheduling unit 15 MAC unit 101 BCH data analysis unit 102 BCH reception buffer unit 103 Sleep operation processing unit 104 Received data judgment unit 105 FCH reception buffer unit 106 Sleep timer unit 107 Timer count calculation unit 108 Decoder unit 109 Frame synchronization detection unit 141 Propagation environment estimation unit 142 Sleep frame calculation unit 143 Sleep control unit 201 AP (wireless base station) 202 MT (wireless terminal station)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshio Kunizawa 6-27-8 Jingumae, Shibuya-ku, Tokyo F-term (reference) 5K033 AA03 AA07 DA01 DA17 DB20 DB25 EA06 5K067 AA43 BB21 CC22 DD44 EE02 EE10 GG11

Claims (10)

[Claims] 1. A radio access system comprising a radio base station for transmitting and receiving information and a radio terminal station for transmitting and receiving information to and from the radio base station, wherein the radio terminal station is in a battery saving state in a standby state. Has a sleep processing unit that performs power control, the sleep processing unit, a propagation environment estimation unit that estimates the propagation environment between the wireless terminal station and the wireless base station, based on the estimation result by the propagation environment estimation unit, A wireless access system comprising: a sleep frame calculating unit that calculates the number of sleep frames during battery saving; and configured to reduce power consumption during battery saving. 2. The sleep frame calculation section increases the number of sleep frames when the propagation environment is good, and reduces the number of sleep frames when the propagation environment is bad, so that when the propagation environment is good. 2. The wireless access system according to claim 1, wherein power consumption is reduced. 3. The radio access system according to claim 1, wherein said propagation environment estimating unit estimates a propagation environment based on a reception level of a signal transmitted from a radio base station. 4. The radio access system according to claim 3, wherein said sleep frame calculating section calculates the number of sleep frames to be large when the reception level is high, and to reduce the number of sleep frames when the reception level is low. . 5. The radio access system according to claim 1, wherein said propagation environment estimation unit estimates a propagation environment based on a reception error rate of a signal transmitted from a radio base station. 6. The sleep frame calculating section increases the number of sleep frames when a reception error rate is high,
The wireless access system according to claim 5, wherein the number of sleep frames is calculated to be small when the reception error rate is low. 7. The propagation environment estimating unit divides a propagation environment into N (N is 1 or more) levels, and performs level transition according to a transition source level (A) to a transition destination level (B). (M (A, B) is 1)
If the number of determinations of the level transition is equal to or greater than the number of determinations M (A, B), the propagation environment is estimated by changing the level output as the estimation result. The wireless access system according to claim 1. 8. When the second number of sleep frames received from the radio base station is larger than the first number of sleep frames calculated by the sleep frame calculator and transmitted to the radio base station, the first sleep mode is used. 2. The wireless access system according to claim 1, wherein the number of frames is adopted as the third number of sleep frames actually used by the wireless terminal station, so as to suppress occurrence of frame synchronization loss due to a reception error. . 9. The radio access system according to claim 1, wherein said propagation environment estimating unit estimates a propagation environment based on a reception level and a reception error rate of a signal transmitted from a radio base station. 10. A radio access system comprising a radio base station for transmitting and receiving information and a radio terminal station for transmitting and receiving information to and from the radio base station, wherein the radio terminal station is in a battery saving state in its standby state. A sleep processing unit for controlling the power of the wireless terminal station. The sleep processing unit has a table of the number of sleep frames during battery saving calculated corresponding to the estimated propagation environment between the wireless terminal station and the wireless base station. A wireless access system configured to reduce power consumption during battery saving.