RU2369012C2 - Device and method for sygnals transmission and reception by means of information of downlink line in standby mode in bwa-communication system - Google Patents

Abstract

FIELD: communication means.

SUBSTANCE: invention pertains to communication technique. Method includes several stages, whereon: information modification of the downlink line is detected; notification about available data for the mobile station from the base-station is accepted; and base-station is notified about the change of the information of the downlink communication line so that, base-station and the mobile station have similar information of the downlink communication line.

EFFECT: providing services to the customers, of various qualities at a high speed of data transmission.

12 cl, 5 dwg, 5 tbl

Description

FIELD OF THE INVENTION

The present invention relates generally to a Broadband Wireless Access (BWA) communication system, and more particularly to a device and method for transmitting and receiving signals between a mobile station (MS) and a base station (BS) when a change in downlink channel information occurs communication when the MS is in standby (sleep) mode.

State of the art

In the communication system of the fourth generation (4G), which is the next generation communication system, research has been actively conducted to provide users with services with different quality of service (QoS) at a high transmission speed. Recently, studies have been actively conducted in the 4G communication system in order to support high-speed services, while providing mobility and QoS in a broadband wireless access (BWA) communication system, such as a wireless local area network (LAN) system and a wireless system urban computer network (MAN, hot water). A typical communication system designed to achieve the goals mentioned above includes the IEEE (Institute of Electrical and Electronics Engineers) 802.16e communication system.

The IEEE 802.16e communication system uses an orthogonal frequency division multiplexing (OFDM) scheme and an orthogonal frequency division multiplexing (OFDMA) scheme to support a broadcast network for a physical channel of a WAN system.

1 is a block diagram schematically illustrating a conventional IEEE 802.16e mobile communication system. Referring to FIG. 1, an IEEE 802.16e communication system has a multi-cell structure including a cell 100 and a cell 150. In addition, the IEEE 802.16e communication system includes a BS 110 controlling a cell 100, a BS 140 controlling a cell 150 , and a plurality of MS 111, 113, 130, 151 and 153. The transmission and reception of signals between the BS 110 and 140 and the MS 111, 113, 130, 151 and 153 is performed using the OFDM / OFDMA scheme. This document MS 130 is located in the boundary region, i.e. in the handover area between the cell 100 and the cell 150. Therefore, when the MS 130 moves to the cell 150 controlled by the BS 140, during transmission and reception for the BS 110, the serving BS for the MS 130 changes from the BS 110 to the BS 140.

In the IEEE 802.16e communication system, MS power consumption plays an important role in the overall system performance. Therefore, standby operation and active operation corresponding to standby operation are proposed for the BS and MS in order to minimize power consumption of the MS. Additionally, in order to cope with the change in the channel state between the MS and the BS, the MS periodically performs a ranking (matching process) to adjust the timing error, frequency offset and transmit power between the BS and the MS.

The following describes the operations for distributing a downlink packet profile in a typical IEEE 802.16a communication system.

First, when the power of the MS is turned on, the MS monitors all frequency ranges set in advance in the MS and detects the pilot signal having the highest intensity, i.e. the largest ratio of carrier signal power to interference and noise (CINR). Additionally, the MS determines the BS transmitting the pilot signal having the highest CINR as the serving BS, which is the BS to which the MS currently belongs. After that, the MS receives the preamble (header) of the downlink frame transmitted from the serving BS and achieves system synchronization between the MS and the serving BS.

When the MS synchronizes with the serving BS, the serving BS transmits the DL (downlink) _MAP message and the UL (uplink) _MAP message to the MS. The DL_MAP message has the message format shown in table 1 below.

Table 1 Syntax The size Notes DL_MAP_Message_Format () { Management Message Type = 2 8 bits PHY Synchronization Field Variable See Related PHY Protocol Specification Dcd count 8 bits Base station id 48 bits Number of DL MAP Element n 16 bits Begin PHY Specification section { See applicable PHY specification section. for (i = 1 i <= n; i ++) For each DL_MAP element from 1 to n DL_MAP Information Element () Variable See Related PHY Protocol Specification If! byte boundary) {Padding Nibble 4 bits Fill free space with spaces to reach the byte limit } } } }

As shown in the table. 1, a DL_MAP message contains many information elements (IEs), such as a Management Message Type representing the type of message to be transmitted, PHY Synchronization defined in accordance with a modulation scheme and a demodulation scheme applied to a physical (PHY) channel to achieve synchronization , A DCD Count representing a counter corresponding to changes in the configuration of a downlink channel descriptor (DCD) message including a downlink packet profile, a Base Station ID representing a BS identifier, and Number of DL_MAP Elements n representing the number of elements after Base Station ID. The DL_MAP message in Table 1 contains the number n of DL_MAP IEs, each of which includes a Downlink Transmission Interval Usage Code (DIUC), which has a value corresponding to a downlink packet profile included in the DCD message. Those. The MS can detect information about a coding scheme (type of forward error correction code (FEC)) and a modulation scheme applied to downlink packets included in a downlink frame by extracting a DIUC value from a DL_MAP message. Therefore, the MS can receive data (data frame) in a downlink packet identifying downlink packets in a downlink frame.

When an MS moves or a change in the channel environment of the MS causes a change in the CINR value of the pilot received by the MS from the serving BS, it is also necessary to change the DIUC value applied to the data to be transmitted by the MS in accordance with the change in the CINR of the pilot.

Additionally, when the BS needs to change the downlink packet profile, the BS changes the packet profile and then transmits a DCD message including the change information to the MS. Then, by receiving the DCD message, the MS can detect a change in the downlink packet profile of the DCD message.

However, when the downlink packet profile changes, i.e. the DCD message changes while the MS is in standby mode, the MS cannot detect a change in the DCD message in real time because the MS is in standby mode.

FIG. 2 schematically illustrates the operation of an MS when a DCD message changes while the MS is in standby mode in a conventional IEEE 802.16e communication system. In FIG. 2, both MS and BS configure protocols for modulation schemes and coding schemes for receiving and transmitting before transmitting and receiving signals between themselves. The protocol settings for modulation schemes and coding schemes are carried out by transmitting and receiving a downlink packet profile, i.e. transmitting and receiving a DCD message.

In addition, it is necessary to prepare protocols for modulation schemes and coding schemes between the BS and the MS in order to enable the MS to resume normally the transmission / reception of data after waking up from standby mode.

However, since the MS does not receive any signals from the BS at all during the sleep mode interval when the MS remains in sleep mode, the MS cannot detect any changes in the downlink packet profile, i.e. in the set of DIUCs made by the BS in the standby interval. When the DIUCs used by the MS and the BS do not match due to the standby operation of the MS, it is not possible to transmit and receive data between the MS and the BS.

The following describes various scenarios in which the DIUCs used by the MS and the BS cease to coincide due to the operation of the MS in standby mode.

The first case corresponds to when the DCD message changes while the MS is in standby mode, i.e. while the MS remains in the standby interval.

In the IEEE 802.16e communication system, the MS detects the DCD counter included in the currently received DL_MAP message and compares the detected value with the value of the DCD counter currently stored in the MS itself. If the DCD counter value included in the DL_MAP message currently received by the MS and the DCD counter value currently stored in the MS are different, the MS detects a change in the DCD message. Those. since the DCD counter values are different, the version numbers of the downlink packet profiles are different. Therefore, the MS can detect the version number of the downlink packet profile using the DCD counter value.

However, in the current IEEE 802.16e communication system, it is not possible to report a downlink packet profile change in an MS that has “woken up” from standby mode. Therefore, if the BS transmits downlink data to the MS using the downlink packet profile of the BS itself without detecting that the BS downlink packet profile is different from the downlink packet profile stored in the MS, the MS cannot normally receive data downlink.

The above scenario is described in more detail below with reference to FIG. 2.

However, it should first be noted that FIG. 2 is based on the assumption that the parameter indicating the value of the DCD counter controlled by the BS 200 is N, the parameter indicating the value of the DCD counter controlled by the MS 250 is M, and the two parameters N and M have an initial value of 0. When the BS 200 detects that it is necessary to change the downlink packet profile while the MS 250 is in standby mode, i.e. in the standby interval, the BS sets the DCD counter N, which is controlled by the BS 200, to 1 (N = 1) in step 211, and transmits the modified DCD message in step 213. Although the BS 200 transmitted the modified DCD message, the MS 250 in the interval Standby cannot detect a change in the DCD message. Therefore, the MS 250 stores the value 0 (M = 0) of the parameter denoting the value of the DCD counter, which is controlled by the MS 250 itself, at step 215.

When the standby interval ends, the MS 250 receives the DL_MAP message from the BS 200 in the listening interval at step 217. In the DL_MAP message, the DCD counter value, more specifically, the parameter value N representing the DCD counter value controlled by the BS 200, is set to 1. Therefore, The MS 250 detects from the value of the DCD counter that it is necessary to receive a new DCD message from the BS 200 base station.

After the listening interval ends, the MS 200 goes into standby mode and waits for the DCD message at step 219. When the BS 200 detects the occurrence of data destined for the MS 250, while the MS 250 is in standby mode, the BS 200 transmits to the MS 250 a TRF_IND message indicating that there is data to be transmitted intended for the MS 250, i.e. a TRF_IND message in which a bit representing the MS 250 in the standby identifier bitmap is marked with a positive value, i.e. 1, at step 221.

After transmitting the TRF_IND message, the BS 200 transmits the data to the MS 250 in step 223. However, as described above, although the BS 200 transmits data using the new modified downlink packet profile, the MS 250 still uses the downlink packet profile to changes. As a result, the DIUC value applied to the data transmitted from the BS 200 to the MS 250 differs from the DIUC value stored in the MS 250, and the MS 250 cannot normally demodulate the data transmitted from the BS 200 in step 225.

As described above, in the first scenario, the DIUC codes used by MS and BS become different, i.e. cease to coincide due to a change in the DCD message while the MS is in standby mode, i.e. while the MS remains in the standby interval.

However, as described below, in the second scenario, the DIUC codes used by the MS and the BS become different due to the standby operation of the MS, since the MS itself changes the DIUC value to be appropriate for the MS while the MS is operating in standby mode i.e. while the MS remains in the standby interval.

More specifically, when the MS moves while it is in the standby interval or when the environmental conditions of the MS channel change, so that the CINR value of the signal of the pilot channel from the serving BS becomes different from this value before the MS enters the standby mode , MS modifies the DIUC value to be appropriate for the MS itself. For example, when the CINR value of the signal of the pilot channel signal measured while the MS is in the standby interval, becomes lower than the CINR value of the signal of the pilot channel signal measured before the MS enters the standby interval if the MS transmits data in the BS using the available DIUC value without updating, there is a high probability that the data transmitted by the MS have an error.

As described above, in the current IEEE 802.16e communication system, if the DCD message changes while the MS is in standby mode, it is not possible to normally transmit and receive data, thereby causing data loss. Data loss can degrade the overall performance of an IEEE 802.16e communications system designed for high-speed data communications. Therefore, there is a need for a solution for transmitting and receiving data, reflecting the change in the message DCD in real time.

SUMMARY OF THE INVENTION

Therefore, the present invention is intended to solve the above and other problems arising in the prior art. An object of the present invention is to provide a system and method for transmitting and receiving signals when downlink channel information is changed in the standby (sleep) mode of a broadband wireless access communication system.

Another object of the present invention is to provide a system and method for notifying about a change in downlink channel information from an MS to a BS when the downlink channel information changes in a standby mode of a broadband wireless access communication system.

Another object of the present invention is to provide a system and method for requesting a change in downlink channel information from an MS to a BS when the downlink channel information is changed in a standby mode of a broadband wireless access communication system.

In order to solve the above and other problems, there is provided a device for transmitting and receiving a signal according to a change in the information of a downlink channel in a communication system with broadband wireless access. The device comprises a mobile station for detecting a change in the downlink channel information, receiving a notification that there is data that the mobile station should receive, and notifications of a change in the downlink channel information; and a base station for changing the downlink channel information and transmitting to the mobile station the changed downlink channel information including information notifying about the change of the downlink channel information, notifications of the availability of data to be transmitted to the mobile station, establishing the correspondence of the channel information of the downlink of the base station and the mobile station with each other by means of a given scheme and data transmission to the mobile station using th information downlink channel, when the base station receives notification of a change of downlink channel information from the mobile station.

In accordance with another aspect of the present invention, there is provided a method for transmitting and receiving a signal according to changing information of a downlink channel by a mobile station in a broadband wireless access communication system. The method consists in detecting a change in the downlink channel information, receiving a notification from the base station that there is data to be received by the mobile station, and notifying the base station of the change in the downlink channel information, thereby indicating that the base station and the mobile station have the same downlink channel information.

In accordance with another aspect of the present invention, there is provided a method for transmitting and receiving a signal according to changing downlink channel information by a base station in a broadband wireless access communication system. The method consists in changing the information of the downlink channel; transmit the changed downlink channel information to the mobile station, including information notifying about the change in the downlink channel information, notify of the availability of data to be transmitted to the mobile station, establish the correspondence of the downlink channel information of the base station and the mobile station with each other by means of one circuit from the first predetermined circuit and the second predetermined circuit and transmit data to the mobile station using the agreed channel information downstream s link, when the base station receives notification of a change of downlink channel information from the mobile station.

Brief Description of the Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, of which:

FIG. 1 is a block diagram schematically illustrating a conventional IEEE 802.16e mobile communication system;

FIG. 2 schematically illustrates the operation of an MS when a DCD message changes while the MS is in standby mode in a conventional IEEE 802.16e communication system;

FIG. 3 schematically illustrates the operation of an MS when a DCD message changes while the MS is in standby mode in an IEEE 802.16e communication system according to an embodiment of the present invention;

FIG. 4 is a flowchart of an MS operating method in an IEEE 802.16e communication system according to an embodiment of the present invention; and

FIG. 5 is a flowchart of a method for operating a BS in an IEEE 802.16e communication system according to an embodiment of the present invention.

A detailed description of the preferred

options for implementation

The following describes preferred embodiments of the present invention with reference to the accompanying drawings. In the following, a detailed description of known functions and configurations contained herein is omitted in cases where this may distract from the subject of the present invention.

The present invention provides a scheme for transmitting and receiving signals via a mobile station (MS) according to a change in downlink channel information in a communication system according to the Institute of Electrical and Electronics Engineers (IEEE) 802.16e standard, which is a Broadband Wireless Access (BWA) communication system. Those. the present invention provides a signal transmission and reception scheme using a single downlink transmission interval (DIUC) usage code between a BS and an MS by notification of a change in a downlink channel descriptor (DCD) message, i.e. changing the value of the DCD counter, from MS to BS, when the DCD message changes while the MS is in standby mode in the IEEE 802.16e communication system.

In addition, the present invention provides a scheme for reliably transmitting and receiving signals between a BS and an MS by real-time requesting a change in the DIUC from the MS to the BS when the ratio of the carrier signal power to interference and noise (CINR) of a reference signal, for example a channel signal the pilot signal measured while the MS is in the standby interval becomes smaller than the CINR of the reference signal measured before the MS has entered the standby mode in the IEEE 802.16e communication system.

The IEEE 802.16e communication system is a BWA communication system using an orthogonal frequency division multiplexing (OFDM) and orthogonal frequency division multiplexing (OFDMA) scheme in which physical channel signals are transmitted via multiple subcarriers to provide high-speed data transmission , and a multi-cell structure is used to support MS mobility. Although the IEEE 802.16e communication system is used herein as an embodiment of the present invention, it should be noted that the present invention can be applied to any communication systems supporting standby operation.

3 schematically illustrates the operation of an MS when a DCD message changes while the MS is in standby mode in an IEEE 802.16e communication system according to an embodiment of the present invention.

As shown in FIG. 1 and 2, both MS and BS configure the protocols for modulation schemes and coding schemes for receiving and transmitting before transmitting / receiving signals between themselves. The protocol settings for modulation schemes and coding schemes are carried out by transmitting and receiving a downlink packet profile, i.e. transmitting and receiving a DCD message. In addition, it is necessary to prepare protocols for modulation schemes and coding schemes between the BS and the MS in order to enable the MS to resume normally the transmission and reception of data after waking up from standby mode. However, since the MS does not receive any signals from the BS at all during the sleep mode interval when the MS remains in sleep mode, the MS cannot detect any changes in the downlink packet profile, i.e. in the set of DIUCs made by the BS in the standby interval. When the DIUCs used by the MS and the BS cease to match due to the standby operation of the MS, it is not possible to transmit and receive data between the MS and the BS.

Those. when the DCD message changes while the MS is in standby mode, i.e. The MS is in the standby interval, the MS detects a DCD counter included in the currently received DL_MAP message, and compares the detected value with the value of the DCD counter currently stored in the MS itself in the IEEE 802.16e communication system. If the DCD counter value included in the DL_MAP message currently received by the MS and the DCD counter value currently stored in the MS are different, the MS detects a change in the DCD message. Those. since the DCD counter values are different, the version numbers of the downlink packet profiles are different. Therefore, the MS detects the version number of the downlink packet profile using the DCD counter value.

As described above, in the current IEEE 802.16e communication system, it is not possible to report a downlink packet profile change in an MS that has "woken up" from standby mode. Therefore, if the BS transmits downlink data to the MS using the downlink packet profile of the BS itself without detecting that the BS downlink packet profile is different from the downlink packet profile stored in the MS, the MS cannot normally receive data downlink from BS.

Therefore, it proposes a scheme for transmitting and receiving data between the MS and the BS using the DIUC, which is updated to be the same when the DCD message changes, which will be described later with reference to FIG. 3.

However, it should first be noted that FIG. 3 is based on the assumption that the parameter indicating the value of the DCD counter controlled by the BS 300 is N, the parameter indicating the value of the DCD counter controlled by the MS 350 is M, and the two parameters N and M have an initial value of 0. When the BS 300 detects that it is necessary to change the downlink packet profile while the MS 350 is in standby mode, i.e. in the standby interval, the BS updates the value of the DCD counter N, which is controlled by the BS 300, to 1 (N = 1) in step 311 and transmits the modified DCD message in step 313. Although the BS 300 transmitted the changed DCD message, the MS 250 in the standby interval mode cannot detect a change in the DCD message. Therefore, the MS 350 stores the value 0 (M = 0) of the parameter denoting the value of the DCD counter, which is controlled by the MS 350, at step 315.

When the standby interval ends, the MS 350 receives the DL_MAP message from the BS 300 in the listening interval at step 317. In the DL_MAP message, the value of the DCD counter, more specifically, the parameter value N representing the value of the DCD counter that is controlled by the BS 200, is set to 1. Therefore The MS 350 detects from the value of the DCD counter that it is necessary to receive a new DCD message from the base station BS 300.

After the listening interval ends, the MS 300 goes into standby mode and waits for a DCD message at step 319. When the BS 300 detects data destined for the MS 350, while the MS 350 is in standby mode, the BS 300 transmits to the MS 350 a TRF_IND message indicating that there is data to be transmitted intended for MS 350, i.e. a TRF_IND message in which a bit representing MS 350 in the standby mode identifier bitmap is marked with a positive value, i.e. 1, at step 321.

After receiving the TRF_IND message, the MS 350 notifies the BS 300 that it has detected a change in the DCD message, i.e. changing the DCD counter value in step 323. At this stage, the MS 350 uses the medium access control (MAC) header message to notify of a change in the DCD counter value in the BS 300. The notification operation of changing the DCD counter value by the MS 350 is described in more detail below.

After receiving a notification of a change in the DCD counter value from the MS 350, the BS detects that the MS 350 still applies the DCD message until the change, i.e. a DCD message having a DCD counter value of 0, and then the BS selects one of the following two schemes in order to solve the problem caused by the difference between the DCD counter values in the BS 300 and the MS 350. That is, in order to prevent incorrect transmission and reception of data due to the difference between the DIUC values, in this case, the BS selects one of the two following schemes in step 325. After that, the BS 300 transmits data to the MS 350 by using the selected scheme in step 327.

In the first scheme, the BS 300 suspends data transmission to the MS 350 until the MS 350 receives a new DCD message, i.e. until the BS 300 broadcasts a new DCD message after receiving a report of a change in the value of the DCD counter. Those. according to the first scheme, the BS 300, having received the new DCD message, performs transmission and reception of data after updating the DIUC MS 350, to be the same as the transmission and reception of data of the BS 300.

According to the second scheme, the BS 300 transmits and receives data by applying the value of the DCD counter currently stored in the MS 350, i.e. by using the DIUC corresponding to the DCD counter value currently stored in the MS 350. FIG. 3 illustrates a case in which the BS 300 transmits data to the MS 350 according to the second scheme.

The second case, in which the MS and the BS use different DIUCs due to the MS operating in standby mode, corresponds to when the MS changes the DIUC value to be appropriate for it when operating in the standby mode, i.e. while the MS is in the sleep mode interval.

When the MS moves while it is in the standby interval or when the environmental conditions of the MS channel change so that the CINR of the signal of the pilot channel from the serving BS becomes different from this value before the MS goes into standby mode, the MS changes DIUC value to be appropriate for MS itself. For example, when the CINR value of the pilot channel signal measured at the time when the MS is in the standby interval, becomes lower than the CINR value of the pilot channel signal measured before the MS enters the standby interval if the MS transmits data in the BS using the available DIUC value without updating, there is a high probability that the data transmitted by the MS have an error. Therefore, the present invention allows the MS to request the DIUC update of the MS even when the MS is in standby mode to establish DIUC correspondence for the MS and the BS, thereby ensuring regular data transmission and reception.

More specifically, according to the present invention, a MAC header message notifying of a change in the value of the DCD counter is used to request a DIUC MS update. A MAC header message for notifying about a change in a DCD counter value and a request for changing a DIUC MS value is described in more detail later in this document.

First, a MAC header message of the present invention for notifying of a change in a DCD counter value and a DIUC MS update request is defined as one of the following three types.

The first type of MAC header message is a message generated based on the MAC header message used in the current IEEE 802.16e communication system. The first type of MAC header message notifies you of a change in the value of the DCD counter using two unused and reserved bits in the MAC header message, i.e. the message header of the physical (PHY) channel of the current IEEE 802.16e communication system. The first type of MAC header message has the format shown in table. 2 below.

table 2 HT = 1 (1) EC = 0 (1) TYPE = 010 (3) PREFERENCE_DIUC (4) UP_TX_POWER (7) UL-HEADROOM (6) DCD CHANGE COUNT LSB (2) CID MSB (8) CID LSB (8) HCS (8)

As can be seen from table 2, all fields except the DCD CHANGE COUNT LSB field (the least significant bit) in the first type of MAC header message are the same as the PHY channel notification header message fields of the current IEEE 802.16e communication system. In Table 2, HT is a field indicating the type of header, EC is a field indicating encryption control, and it always has a value of 0 in the PHY channel notification header message, and TYPE is a field indicating the type of the currently sent MAC message header. When TYPE is marked as 010, this implies that the MAC header message is a PHY channel notification header message.

In Table 2, PREFERENCE_DIUC is a field indicating the DIUC value requested by the MS, UP_TX_POWER is a field indicating the additional transmit power available for the MS, DCD CHANGE COUNT LSB is a field indicating the LSB value of the number of modified DCD messages, CID indicates the base identifier MS, and HCS is a field indicating the control sequence of the headers.

The first type of MAC header message is a MAC header message generated by changing the reserved bits of the PHY channel notification header message of the current IEEE 802.16e communication system in the DCD CHANGE LSB field, which notifies you of a change in the DCD counter value. Two reserved bits that are not currently used in the PHY channel notification header message of the current IEEE 802.16e communication system are used as two LSB bits of the DCD counter specifying the DIUC (PREFERENCE_DIUC) requested by the MS in the first type MAC header message. The first type MAC header message includes PREFERENCE_DIUC and DCD CHANGE COUNT LSB, by which the MS can notify of a change in the DCD counter and a change in DIUC in the BS.

The second type MAC header message is a downlink packet profile change request and frequency band request header message, which is a newly generated message to notify of a change in the DCD counter value and to request a change in the MS DIUC.

The second type of MAC header message has the format shown in table 3 below.

Table 3 HT = 1 (1) EC = 0 (1) TYPE = 100 (3) BR (11) REQUESTED DOWNLINK BURST PROFILE (8) CID MSB (8) CID LSB (8) HCS (8)

In Table 3, the HP, EC, HCS, and CID fields of the second type of MAC header message are the same as the HT, EC, HCS, and CID fields of the first type of MAC header message shown in Table 2, so a description of them will not be repeated.

In Table 3, TYPE is a field indicating the type of the currently sent MAC header message. When TYPE is marked as 100, this implies that the MAC header message is a downlink packet profile request and bandwidth request header message. Additionally, the BR field indicates the frequency band requested by the MS, which has a value of 0 when there is no data that the MS should transmit via the uplink. The REQUESTED DOWNLINK BURST PROFILE field is 8 bits long, of which four bits from zero to third bits represent the DIUC requested by MS, and four bits from fourth to seventh bits represent four LSB bits of the DIUC specifying DCD requested by MS . REQUESTED DOWNLINK BURST PROFILE has the format shown in table 4 below.

Table 4 Title Type of
(1 byte) Length Value REQUESTED DOWNLINK BURST PROFILE one one Bits 0-3: DIUC of the downlink packet profile requested by the MS for downlink traffic
Bits 4-7: LDB Configuration Change Count value for a DCD specifying a packet profile associated with a DIUC

The second type MAC header message includes a REQUESTED DOWNLINK BURST PROFILE field whereby the MS can notify of a change in the DCD counter and a change in the DIUC in the BS.

The third type MAC header message is a downlink packet profile change request and frequency band request header message, which is a newly generated message to notify of a change in a DCD counter value and to request a change in MS DIUC.

The third type of MAC header message has the format shown in table 5 below.

Table 5 HT = 1 (1) EC = 0 (1) TYPE = 100 (3) BR (11) CINR (7) DCD Change Indication (1) CID MSB (8) CID LSB (8) HCS (8)

In Table 5, the HP, EC, HCS and CID fields of the third type MAC header message shown in Table 5 are the same as the HT, EC, HCS and CID fields of the first type MAC header message shown in Table 5. 2, therefore, a repetition of their description is omitted.

In Table 5, TYPE is a field indicating the type of the currently sent MAC header message. When TYPE is marked as 100, this implies that the MAC header message is a downlink packet profile request and bandwidth request header message. Although the message types of the MAC header of the second type and the MAC header of the third type may differ from each other, they are set to be the same in the present embodiment to provide clarity and convenience of description.

In Table 5, the BR field indicates the frequency band requested by the MS, which is set to 0 when there is no data that the MS should transmit via the uplink. Additionally, the CINR field indicates the CINR of the downlink signal, for example, the pilot channel signal received by the MS, and the DCD Change Indication field indicates whether the DCD counter has been changed.

As shown in Table 5, the third type MAC header message has a format similar to the second type MAC header message format. Those. just like a second type MAC header message, a third type MAC header message is a message indicating a request to change the profile of the downlink packets and a request for a frequency band. However, the second type MAC header message and the third type MAC header message differ in the request process for changing the downlink packet profile.

The following describes the ways in which a second type MAC header message and a third type MAC header message request a change in the downlink packet profile.

First, the second type MAC header message is used by the MS, which directly requests the assignment of the DIUC value, which is appropriate for the MS, from the BS to change the DIUC value when moving the MS during the standby interval or changing the channel environment causes CINR the pilot channel signal from the BS become different from the CINR before the MS enters standby mode. Therefore, in the second type MAC header message, four bits from zero bit to third bit out of eight bits of the REQUESTED DOWNLINK BURST PROFILE field are used to express the DIUC value requested by the MS.

In contrast, a third type MAC header message is used by the MS to request the assignment of the DIUC value appropriate for the MS by notifying the CINR of the received pilot channel signal instead of using the MS, which directly requests the assignment of the DIUC value that is appropriate for the MS , from the BS, to change the DIUC value when moving the MS during the standby interval or changing the channel environment causes the CINR of the pilot channel signal from the BS to become different from the CINR to MS transition to standby mode. Therefore, the third type MAC header message includes a CINR field for notifying the CINR of the pilot channel signal received by the MS. In order to notify the quality of the MS channel, the third type MAC header message may include CINR as well as other information capable of expressing the quality of the MS channel.

Additionally, to notify of a change in the DCD counter value, the second type MAC header message directly transfers the DCD counter value stored in the MS to the BS using four bits from the fourth bit to the seventh bit of the eight bits of the REQUESTED DOWNLINK BURST PROFILE field.

In contrast, the third type MAC header message uses the DCD change indication field to express a change in the value of the DCD counter. Those. when the value of the DCD counter currently stored in the MS is different from the value of the DCD counter received by the MS in the listening interval, the value of the DCD change indication field is set to 1. When the value of the DCD counter currently stored in the MS is equal to the value of the DCD counter received by the MS in the listening interval, the value of the DCD change indication field is set to 0. Therefore, the BS can detect whether the DCD counter value has changed from the value of the DCD change indication field of the third type MAC header message.

The time point at which the third type MAC header message is transmitted must be the same as the time point at which the first type MAC header message and the second type MAC header message are transmitted. Those. when the DCD counter value currently stored in the MS is different from the DCD counter value of the DCD message received by the MS in the listening interval, or when it is necessary to change the DIUC value due to a change in the CINR of the downlink signal received by the MS, the MS transmits a MAC message header of the third type.

Further, even when the DCD counter value currently stored in the MS is equal to the DCD counter value of the DCD message received by the MS in the listening interval, and it is not necessary to change the DIUC value taking into account the CINR of the downlink signal received by the MS, the MS can use the message A MAC header of the third type to acknowledge the TRF_IND message.

When the MS notifies its CINR value through a third type MAC header message to the BS, the BS determines a DIUC value appropriate for the MS in accordance with the CINR value of the MS. The process in which the BS determines a DIUC value appropriate for the MS according to the CINR value of the MS is not described herein, since it is not directly related to the present invention.

Additionally, when the MS notifies of a change in the value of the DCD counter by a third type MAC header message in the BS, i.e. when the MS transmits a third type MAC header message containing a DCD change indication field having a value of 1, the BS stops transmitting traffic data destined for the MS until the MS receives a DCD message corresponding to the changed value of the DCD counter, t .e. until the BS retransmits the DCD message corresponding to the changed value of the DCD counter.

In addition, even before the BS retransmits the DCD message corresponding to the changed DCD counter value, if the BS continuously controls and detects the DCD counter value of the DCD message stored in the MS, the BS can transmit traffic data destined for the MS using the DIUC specified in the DCD message corresponding to the value of the DCD counter stored in the MS.

Therefore, unlike the first type MAC header message and the second type MAC header message, the third type MAC header message allows the MS to directly notify the received CINR of the downlink signal to the BS. Therefore, the BS can accurately determine the DIUC for the MS, as well as the amount of power to be transmitted to the MS, the number of data encoding retries, etc.

Further, new MAC header messages proposed by the present invention, including a first type MAC header message shown in Table 2, i.e. a message created by modifying a PHY channel notification header message used in the current IEEE 802.16e communication system, a second type MAC header message and a third type MAC header message are compared with each other.

The first type of MAC header message is advantageous in that it is a reusable message that is created by modifying the PHY channel notification header message used in the current IEEE 802.16e communication system. However, while the first type MAC header message allows 2 LSB bits of the DCD counter to be transmitted, the second type MAC header message allows 4 LSB bits of the DCD counter to be transmitted. Therefore, the second type MAC header message is more suitable than the first type MAC header message when the MS remains in standby mode for a relatively long time, and the DCD message changes relatively frequently.

Additionally, a second type MAC header message and a third type MAC header message can be used to simultaneously acknowledge a change in the downlink packet profile and a band allocation request. Those. even when the MS is in standby mode, the MS can request a frequency band via an uplink to the BS if data appears that needs to be transmitted to the BS. In this case, the MS can simultaneously confirm the change in the profile of the downlink packets and request the allocation of the frequency band using the MAC header message of the second type and the MAC header message of the third type. By simultaneously confirming the change in the downlink packet profile and the bandwidth allocation request, it is possible to minimize the burden of transmitting signals in the uplink.

FIG. 4 is a flowchart of an MS operating method in an IEEE 802.16e communication system according to an embodiment of the present invention.

As described above, the second type MAC header message and the third type MAC header message are similar in function, i.e. both of them are downlink packet profile request header and frequency band request messages. Therefore, it should be noted that one of the second type MAC header message and the third type MAC header message can be selectively used as a downlink packet profile request message and a bandwidth request message in the following description of FIG. four.

Referring to FIG. 4, while the MS is in standby mode at step 411, the MS checks whether the standby mode interval has completed at step 413. When the standby interval is not yet completed, the MS remains in the standby interval at step 411.

When the standby interval is completed, the MS goes into the listening interval. In step 415, the MS receives the pilot channel signal from the serving BS, measures the CINR of the pilot channel signal and determines from the measured CINR whether the DIUC of the MS itself needs to be changed.

At step 417, the MS compares the DCD counter value of the DL_MAP message from the BS with the DCD counter value stored in the MS, and determines whether the DCD counter value has changed. In step 419, the MS receives the TRF_IND message from the BS and checks if the bit for the MS is marked on the bitmap of the standby mode identifier of the received TRF_IND message with a value representing a positive identifier, i.e. 1. When the bit is not marked by 1, the MS returns to step 411.

As a result of the check in step 419, when the bit is marked by 1, the MS checks whether the uplink frequency band is allocated for the MS, in step 421. The MS proceeds to step 423, when the MS allocates the uplink frequency band, and proceeds to step 429 when the MS is not allocated uplink frequency band.

At 423, the MS checks whether it is necessary to notify of a change in the value of the DCD counter or to request a change in the DIUC. When it is necessary to notify of a change in the value of the DCD counter or to request a change in the DIUC, the MS selects one MAC header message from the first type MAC header message, i.e. PHY channel notification header messages, and second and third type MAC header messages, i.e. downlink packet profile request and frequency band request header messages, notifies of a change in the DCD counter value or requests a change in the DIUC by using the selected message in step 425. In step 425, the MS obeys the IEEE 802.16e communication system definition in selecting one MAC message header from the MAC header messages of the first, second and third types.

When it is not necessary to notify the DCD counter of a change in value and request a change in the DIUC, the MS may send a downlink packet profile request header message and a frequency band request message instead of a frequency band request header after assigning a downlink packet profile request header message to the BR field and requesting a frequency band of value 0 in step 427.

At 429, the MS switches from the standby mode to the wake-up mode and then performs the normal operation.

As described above, the second type MAC header message and the third type MAC header message are similar in function, i.e. are downlink packet profile request header and frequency band request messages. Therefore, it should be noted that one of the second type MAC header message and the third type MAC header message can be selectively used as a downlink packet profile request header message and a bandwidth request in the following description of FIG. 5.

5 is a flowchart of a method for operating a BS in an IEEE 802.16e communication system according to an embodiment of the present invention. Referring to FIG. 5, while the corresponding MS controlled by the BS is in sleep mode at step 511, the BS checks whether the sleep mode interval of the corresponding MS is completed at step 513. When the sleep mode interval is not yet completed, the BS returns to step 511.

When the MS standby interval is completed, the BS goes into the listening interval. At step 515, the BS checks whether data intended for the corresponding MS is stored in the buffer, i.e. data to be transmitted to MS. When there is no data to be transmitted to the MS, the BS proceeds to step 517.

At step 517, the BS transmits the TRF_IND message after marking the bit for the corresponding MS in the bitmap of the standby identifier of the TRF_IND message with a value representing a negative indication, i.e. 0, and then proceeds to step 519. In step 519, the BS updates the standby interval of the corresponding MS, and in step 521, the BS controls the standby mode MS based on the updated standby interval.

As a result of the verification in step 515, when there is no data to be transmitted to the MS, the BS transmits the TRF_IND message after marking the bit for the corresponding MS in the standby mode identifier bitmap of the TRF_IND message with a value representing a positive indication, i.e. 1, at step 523.

At step 525, the BS allocates an uplink frequency band to the corresponding MS and receives, via a dedicated uplink frequency band, one MAC header message from a first type MAC header message, i.e. PHY channel notification header messages, and second and third type MAC header messages, i.e. message heading request to change the profile of the packet downlink and request bandwidth. At step 525, the BS obeys the IEEE 802.16e communication system definition in receiving first, second, and third type MAC header messages.

At step 527, the BS determines based on the analysis of the first, second, or third type MAC header message received from the MS whether there is a notification of a change in the value of the DCD counter or a request for a change in the DIUC. When there is a request to change the DIUC, the BS changes the DIUC according to the request of the MS in step 529.

As a result of the determination in step 527, when there is a notification of a change in the value of the DCD counter, the BS transmits data to the MS based on the DIUC of the downlink packet profile of the DCD message corresponding to the value of the DCD counter stored in the MS, or stops transmitting data until The BS will not transmit the DCD message to the MS at step 531.

When there is no notification of a change in the value of the DCD counter, nor a request to change the DIUC as a result of determination at step 527, the BS proceeds directly to step 533.

At step 533, the BS controls the MS to enter wake-up mode, and then terminates the process.

According to the present invention, when the DCD message changes, i.e. when the downlink packet profile changes, in standby mode of a broadband wireless access communication system using an OFDM / OFDMA scheme, for example, an IEEE 802.16e communication system, or when it is necessary to change the DIUC of the MS due to a change in the CINR of the MS, the MS notifies of a change in the DCD message and requests a DIUC change from the BS so that the BS and MS transmit and receive data with the same DIUC, thereby maximizing transmission efficiency.

Although the present invention has been shown and described with reference to its specific embodiments, those skilled in the art should understand that various changes in form and content can be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (12)

1. The method of transmitting and receiving a signal through a mobile station in a communication system with broadband wireless access, namely, that:
receiving a downlink message from the MAP base station including counting a first change in the description of the downlink channel;
comparing the count of the first change in the description of the downlink channel with the stored count of the change in the description of the downlink channel received before counting the first change in the description of the downlink channel;
measuring a ratio of carrier power to interference and noise level (CINR) of a signal from a downlink base station; and
transmit a header message to the base station in order to request the frequency band and profile change of the downlink packets,
wherein the header message includes bandwidth request information measured by the CIRN, and a comparison result indicating whether the count of the first downlink channel description change is the stored count of the downlink channel description state change or not. 2. The method according to claim 1, wherein the downlink packet profile includes downlink channel information including a set of information about modulation schemes and coding schemes to be applied to the downlink channel. 3. The method according to claim 1, in which the header message includes at least one type information indicating the type of the header message, the connection identifier (CID) of the mobile station (MS) and the control sequence of the header (HCS). 4. The method of transmitting and receiving a signal through a base station in a communication system with broadband wireless access, namely, that:
receiving a header message requesting a frequency band and changing the profile of the downlink packets from the mobile station, the header message including band request information, a measured ratio of carrier power to interference and noise level (CINR) of the signal from the downlink base station, and a comparison result indicating whether the count of the first change in the description of the downlink channel included in the MAP message of the downlink is equal to the stored count of the state change description Nia downlink channel received prior to the first change count description downlink channel or not; and
establish the correspondence of the downlink packet profile of the base station and the mobile station with each other, in the case where the comparison result indicates that the count of the first change in the description of the downlink channel is not equal to the stored count of the change in the description of the downlink channel description. 5. The method of claim 4, wherein the downlink packet profile includes downlink channel information including a set of information about modulation schemes and coding schemes to be applied to the downlink channel. 6. The method according to claim 4, in which the header message includes at least one type information indicating the type of the header message, the connection identifier (CID) of the mobile station (MS), and the header control sequence (HCS). 7. A device for transmitting and receiving a signal in a communication system with broadband wireless access, comprising:
base station and
a mobile station in order to receive a downlink message from the MAP base station including counting a first change in the description of the downlink channel; compare the count of the first change in the description of the downlink channel with the stored count of the change in the description of the channel downlink received before counting the first change in the description of the channel downlink; measure the ratio of carrier power to the level of interference and noise (CINR) of the signal from the base station downlink; and transmit to the base station a header message in order to request a frequency band and a change in the profile of the downlink packets,
wherein the header message includes bandwidth request information measured by CINR and a comparison result indicating whether the count of the first change in the downlink channel description is equal to the stored count of the change in the description of the downlink channel description or not. 8. The apparatus of claim 7, wherein the downlink packet profile includes downlink channel information including a set of information about modulation schemes and coding schemes to be applied to the downlink channel. 9. The device according to claim 7, in which the header message includes at least one type information indicating the type of header message, connection identifier (CID) of the mobile station (MS), and the control sequence of the header (HCS). 10. A device for transmitting and receiving a signal in a communication system with broadband wireless access, comprising:
mobile station; and
a base station in order to receive a header message requesting a frequency band and changing the profile of the downlink packets from the mobile station, the header message including bandwidth request information, a measured ratio of carrier power to interference level and noise (CINR) of the signal from the base station downlink, and a comparison result indicating whether the count of the first change in the description of the channel downlink included in the MAP message downlink stored on account changes description downlink channel status, received before the first change count description downlink channel or not; and to establish the correspondence of the downlink packet profile of the base station and the mobile station with each other,
in the case where the comparison result indicates that the count of the first change in the description of the downlink channel is not equal to the stored count of the change in the description of the channel downlink. 11. The apparatus of claim 10, wherein the downlink packet profile includes downlink channel information including a set of information about modulation schemes and coding schemes to be applied to the downlink channel. 12. The device according to claim 10, in which the header message includes at least one type information indicating the type of the header message, the connection identifier (CID) of the mobile station (MS), and the control sequence of the header (HCS).

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