KR20080081233A - Method for updating channel information in broadband wireless access system - Google Patents

Abstract

A method for updating channel information in a BWA(Broadband Wireless Access) system is provided to enable an MS(Mobile Station) to maintain idle mode even though the MS fails to receive a paging advertising message as the DCD(Downlink Channel Descriptor) is modified. An MS in power-saving mode receives an IE(Information Element) containing a transmission frame field, which indicates a frame at which a channel descriptor configuration change counter and a channel descriptor are transmitted, from a BS(Base Station). If the channel descriptor configuration change counter is modified after the MS decodes the IE for the last time, the MS maintains a waken state in order to receive the channel descriptor at the frame the transmission frame field indicates, even though the MS is scheduled to a paging unavailable interval. Before receiving the channel descriptor, the MS maintains power-saving mode. Also the MS receives indication information which indicates whether the channel descriptor is scheduled to be transmitted during the next paging unavailable interval.

Description

Method for updating channel information in broadband wireless access system {Method for updating channel information in Broadband Wireless Access System}

The present invention relates to a method for performing idle mode applied to a broadband wireless access system, and more particularly, to allow a mobile station in an idle mode to more efficiently obtain DCD / UCD information. It relates to a method for doing so. The present invention also relates to a method for updating channel information in a broadband wireless access system.

In the broadband wireless access system, the idle mode operation is as follows. The paging area is defined as the entire area that the base stations included in the set of a plurality of base stations called the paging group are in charge. The base stations included in the same paging group have the same paging period (Paging_Cycle) and paging offset (Paging_Offset).

The mobile station may request the base station to switch to the idle mode, and when the base station transmits its paging group ID and the corresponding paging period and paging offset, the mobile station can switch to the idle mode state.

During idle mode, it is possible for the mobile station to determine whether to remain in idle mode or terminate through a paging broadcast message (MOB-PAG-ADV) delivered in broadcast form from the base station at each paging period promised.

When an uplink traffic that a mobile station in idle mode needs to transmit occurs, the mobile station can exit idle mode at any time. On the other hand, when downlink traffic to be delivered to the mobile station in the idle mode occurs, the base station may cause the mobile station in the idle mode to exit the idle mode through a paging broadcast message.

On the other hand, if the mobile station in the idle mode does not receive the paging broadcast message at a predetermined time due to moving to another paging area or losing synchronization, the mobile station must exit the idle mode.

The present invention provides a method for performing idle mode in which a mobile station in an idle mode acquires DCD / UCD information more efficiently in a broadband wireless access system, so that downlink traffic can be accessed more quickly. The purpose is to provide.

In addition, the present invention, even if the mobile station moves to another base station area of the same paging group, or even in the same base station area does not receive a paging broadcast message due to the change of the DCD, the idle mode to perform the idle mode There is another purpose to provide.

According to an aspect of the present invention, there is provided a method for performing idle mode of a mobile station applied to a broadband wireless access system, the method comprising: receiving a message broadcast in a paging area at a predetermined paging period; And receiving uplink channel descriptor and downlink channel descriptor information within a next paging period according to uplink channel descriptor (UCD) and downlink channel descriptor (DCD) transmission information included in the message. It comprises a step.

In addition, the present invention provides a method for performing an idle mode of a mobile station applied to a broadband wireless access system, the method comprising: receiving a message broadcasted at a predetermined paging period in a paging area; Examining whether or not transmission offset information indicating whether the uplink channel descriptor and the downlink channel descriptor are transmitted at a point in time and according to the check result, the uplink channel descriptor and the downlink channel descriptor Receiving the information.

In addition, the present invention provides a method for performing idle mode of a mobile station applied to a broadband wireless access system, at a first time point, a first paging broadcast message (MOB_PAG-ADV) and a first downlink. Receiving a Downlink Channel Descriptor (DCD) message and after a time elapses by a paging period at the first time point, a second paging broadcast message (MOB_PAG-ADV) and a second downlink channel descriptor (DCD) Receiving a Descriptor) message.

Meanwhile, the present invention provides a method of performing an idle mode of a mobile station applied to a broadband wireless access system, and as a coding and modulation scheme of a message broadcasted at a constant paging period in a paging area is changed. Receiving a message requesting initial ranging messaging and performing initial ranging.

In a preferred embodiment of the present invention, a method for updating channel information of a terminal in a power saving mode includes transmitting a channel descriptor configuration change counter and a channel descriptor transmitted by a terminal in a paging segment. The method may include receiving an information element (IE) including a transmission frame field indicating a frame. In this case, if the channel descriptor configuration change counter has changed since the terminal decoded the information element last time, the terminal may remain awake to receive the channel descriptor in the frame indicated by the transmission frame field even when the terminal is scheduled for a non-pageable period. have.

One preferred aspect of the present invention may further comprise maintaining a power saving mode prior to receiving a channel descriptor.

One preferred aspect of the present invention may further comprise receiving indication information indicating whether the channel descriptor is scheduled to be transmitted during a next paging unavailable interval. In this case, the paging unavailable interval is preferably a period in which communication between the terminal and the base station in the power saving mode is impossible.

In one preferred aspect of the present invention, the information element (IE) is preferably received in the paging segment. In this case, the paging segment is preferably a section in which communication is performed between the terminal and the base station in the power saving mode.

In a preferred aspect of the present invention, the channel descriptor may be any one of an uplink channel descriptor (UCD) and a downlink channel descriptor (DCD). In this case, at least one of the UCD and the DCD may be a broadcast message.

In a preferred aspect of the present invention, the information element (IE) may be a broadcast control pointer information element (Broadcast Control Pointer IE).

In addition, the transport frame field is 8 bits in size and may indicate when the next channel descriptor is transmitted. In this case, the channel descriptor may be a broadcast message.

In a preferred aspect of the present invention, the power saving mode may be either an idle mode or a sleep mode.

In a preferred aspect of the present invention, the transport frame field may indicate a frame number.

The present invention has the effect of allowing the mobile station in idle mode to obtain DCD / UCD information efficiently in a broadband wireless access system so that it can quickly access the network when necessary. In addition, the present invention has another effect of maintaining the idle mode even when the paging broadcast message is not received as the DCD is changed.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the detailed description of the present invention, a detailed description of the idle mode and a detailed description related to the DCD / UCD may refer to the IEEE802.16 document which is a standard for a broadband wireless access system.

In Idle Mode, a mobile station in a paging zone consisting of areas of a plurality of base stations (hereinafter, referred to as' BS's) receives a paging broadcast message (MOB_PAG-ADV) transmitted periodically. .

Table 1 shows an example of a paging-group-action for configuring a paging area. The inter-base station message may be transmitted over the wire between the base stations.

The inter-base station message may be used for the following four purposes according to a combination of action bits. That is, the receiving base station (target BS) can be designated as a specific paging group (Action = 0), the receiving base station can be excluded from the specific paging group (Action = 1), and the receiving base station belongs to which paging group. You can ask if it is (Action = 2). Meanwhile, the transmitting base station (Sender BS) may be informed to which paging group (Action = 3).

Since one base station may belong to one or more paging areas, the paging-group-action may include information on a plurality of paging groups. Through the paging-group-action, base stations can know the paging period and paging offset used in each paging area. Meanwhile, base stations can be dynamically allocated to a paging group.

Table 2 is an example of a deregistration request message (DREG_REQ) used by the mobile station to switch to idle mode.

The mobile station may request that the mobile station switch to idle mode by setting the de-registration request code of the deregistration request message DREG_REQ to 0x01 and transmitting it to the base station. Can be delivered). The base station receiving the deregistration request message DREG_REQ may respond to the request of the mobile station through the deregistration command message DREG_CMD.

Table 3 shows an example of a deregistration command message (DREG_CMD).

The base station allows the transition to the idle mode through the action code of the deregistration command message (DREG_CMD) (Action Code = 0x05), or requests the transition to the idle mode again after a certain time (Action Code = 0x06), it can be no longer requested to switch to idle mode until it sends a deregistration command message (Action Code = 0x07).

Table 4 shows an example of an operation code of the deregistration command message (DREG_CMD).

PLV (Paging Group ID), Paging_Cycle, and Paging Offset ) Can be passed. Thereafter, the mobile station can maintain the idle mode or terminate the idle mode by receiving a paging broadcast message (MOB-PAG-ADV) at a predetermined paging period and paging offset.

Table 5 shows an example of a paging broadcast message (MOB-PAG-ADV).

In a broadband wireless access system, in order for a mobile station to enter a network by powering on (Network Entry), or to reenter the network due to handover or other reasons, it is up / down with the current base station. It is necessary to receive a Downlink Channel Descriptor / Uplink Channel Descriptor (hereinafter, 'DCD / UCD').

Table 6 shows an example of the DCD message.

Table 7 shows an example of a UCD message.

The DCD / UCD messages are physical layer related parameters to be applied in a burst period allocated to downlink and uplink, respectively, and include information on a modulation scheme and a forward error correction (FEC) code type. In addition, according to various types of forward error correction codes, necessary parameters (eg, K, R values of R-S Code, etc.) are prescribed. Such parameters are given by a burst profile defined for each Uplink Interval Usage Code (UIUC) and Downlink Interval Usage Code (DIUC) in UCD and DCD, respectively.

Since the information to be included in the DCD / UCD message varies depending on the physical layer, the items shown in Tables 8 and 9 may be included in the TLV Encoded Information for the overall channel field of each message.

Table 8 shows an example of items included in the 'TLV Encoded Information for the overall channel' field of the DCD message when the physical layer is Orthogonal Frequency Division Multiple Access (OFDMA).

Table 9 shows an example of items included in the 'TLV Encoded Information for the overall channel' field of the UCD message when the physical layer is Orthogonal Frequency Division Multiple Access (OFDMA).

In addition to the items shown in Tables 8 and 9, many items may be included in the DCD / UCD message.

As shown in Tables 6-9 above, the DCD / UCD mesh needs to contain a great deal of information, so it is inefficient to decode it whenever the mobile receives a DCD / UCD message. Therefore, the DCD / UCD message shown in Table 6 and Table 7 includes configuration change count information. The configuration change count may be increased by one if the values included in the current DCD / UCD message are different from the values included in the previous DCD / UCD message.

As mentioned above, the DCD / UCD message is not only very long, and the information contained in the DCD / UCD message is generally not frequently changed, so it is not transmitted in every frame, but periodically, It may be sent at 10 second intervals.

After the base station transmits a DCD / UCD message containing the new value (the value of the configuration change count included in the DCD / UCD message is increased by one), all mobile stations in its area receive the DCD / UCD message. In order to be able to do this, after a certain time interval, the actually changed value of DCD / UCD is applied to bursts of up / down frames.

In this case, this fact can be informed to the mobile station through the 'DCD / UCD Count' field included in the DL-MAP message and the UL-MAP message shown in Tables 10 and 11. Since the DL / UL-MAP message and the DCD / UCD message use pre-appointed physical layer values, the mobile station can decode even if the value of the DCD / UCD message changes.

Table 10 shows an example of DL-MAP messages.

Table 11 shows an example of the UL-MAP message.

A mobile station receiving a DL-MAP / UL-MAP whose DCD / UCD count value is different from the previous one is included in the corresponding DL-MAP / UL-MAP using the values included in the most recently received DCD / UCD message. Decoded bursts will be decoded.

1 is a diagram for explaining an idle mode operation according to a change in a DCD / UCD value.

If the paging broadcast message is implemented to be transmitted using a predetermined coding and modulation scheme, the mobile station can receive the paging broadcast message even if the mobile station does not receive the DCD / UCD message while in the idle mode.

However, if a predetermined coding and modulation scheme is not used, and if the mobile station in idle mode does not receive a DCD / UCD message, the mobile station can decode a paging broadcast message if the base station changes the coding and modulation scheme. Idle mode must be exited. On the other hand, when moving between base stations belonging to the same paging group but using different coding and modulation schemes, the mobile station must terminate the idle mode because it cannot decode the paging broadcast message. In addition, if the mobile station does not receive a DCD / UCD message at all while in the idle mode, the delay time may be long because the DCD / UCD message must be received when reentering the network later. Thus, there is a need for a mobile station in idle mode to receive a DCD / UCD message even when in idle mode.

In the case where a mobile station in idle mode receives a DCD / UCD message, the mobile station in idle mode decodes the downlink frame for a short period of time. Therefore, when the DCD / UCD value changes during a paging unavailable interval in which the mobile station does not decode the downlink frame to prevent power consumption, or when the mobile station moves to another base station belonging to the same paging group (DCD / The UCD count is an independent variable that is set individually for each base station), and the mobile station must continuously receive and decode downlink frames in order to receive new DCD / UCD messages. However, as described above, since the DCD / UCD message is transmitted with a fairly long period (up to 10 seconds), the power efficiency of the mobile station in the idle mode may be degraded.

Table 12 shows an example of a paging broadcast message (MOB-PAG-ADV).

The paging broadcast message shown in Table 12, unlike the paging broadcast message shown in Table 5, contains a DCD / UCD Transmission Indication to indicate whether transmission of the DCD / UCD message is scheduled during the next paging period. .

If the DCD / UCD Transmission Indication of the message is set to 1, the DCD / UCD Transmission Offset shown in Table 13 may be included in the TLV form in the paging broadcast message.

The DCD / UCD transmission identifier of the paging broadcast message shown in Table 12 and the DCD / UCD transmission offset shown in Table 13 are DL-MAP IEs in the form of the common downlink announcement (Common_DL_Notification_IE) DL-MAP IE shown in Table 14. May be included in the MAP message. The DCD / UCD Transmission Offset Bitmap is used to distinguish whether the included offset is for DCD or UCD.

Table 14 shows an example of a downlink notification DL-MAP message.

FIG. 2 is a diagram illustrating an embodiment of a mobile station when transmitting a paging broadcast message shown in Table 12 or a common downlink published DL-MAP IE shown in Table 14. FIG. Referring to FIG. 2, when the mobile station in idle mode detects a change in the DCD / UCD count value in the DL / UL-MAP during the paging listening period, the DCD / UCD transmission identifier of the paging broadcast message transmitted in the paging listening period. You need to know the value of (Transmission Indication). If the value of the DCD / UCD transmission identifier is '0', it can be seen that the UCD / DCD message is not transmitted at least for the next non-pageable period, so the mobile station performs normal idle mode procedure until the next paging listening period without waiting for the UCD / DCD message. do.

If the DCD / UCD Transmission Indication of the paging broadcast message delivered in the next paging listening period is '1', it means that the UCD / DCD message is transmitted during the next paging dead period. It does not enter the paging deadline until it receives a DCD / UCD message.

FIG. 3 is a diagram illustrating an embodiment of the operation of a mobile station when the DCD / UCD Transmission Offset shown in Table 13 or Table 14 is used. In the case of FIG. 3, the mobile station can receive the DCD / UCD message even during the paging period by transmitting the paging broadcast message with the exact time when the DCD / UCD message will be included.

Another embodiment of the present invention is a method for indicating whether a DCD / UCD message is transmitted during a next paging period through a DCD / UCD Transmission Offset rather than a DCD / UCD Transmission Indication. In this case, the DCD / UCD Transmission Indication is omitted from the paging broadcast message of Table 12. If the base station needs to transmit a DCD / UCD message during the next non-paging period, the DCD / UCD Transmission Indication TLV parameter is included in the paging broadcast message, and the receiving MS receives the DCD even if the paging listening period ends. It does not enter the paging deadline until it receives a / UCD message. On the other hand, if the base station does not transmit the DCD / UCD message during the next non-paging period, the paging broadcast message does not include the DCD / UCD Transmission Indication (LV) TLV parameter, the mobile station receives the DCD during the next non-paging period / UCD determines that the message is not transmitted and performs normal idle mode procedure until the next paging listening period.

4 is a diagram illustrating an embodiment of an operation of a mobile station when a paging period and a DCD / UCD message transmission period are matched. As shown in FIG. 4, if the paging period in the idle mode and the period in which the DCD / UCD message is transmitted (DCD / UCD Interval) are set to be the same, all mobile stations in the idle mode in the paging listening period are used during every paging listening period. Since a DCD / UCD message can always be received, the function to be achieved in the present invention can be implemented without the operation proposed in the present invention.

FIG. 5 is a diagram illustrating an operation of a mobile station when the base station changes its coding and modulation scheme and causes the mobile station in idle mode to perform initial ranging. In order to perform initial ranging, a DCD / UCD message must be received. Therefore, if the mobile station performs the initial ranging, this allows the base station to send a DCD / UCD message to the mobile station in the idle mode.

That is, the mobile station receiving the ranging request through the paging broadcast message performs the ranging as follows. The mobile station receives a DCD / UCD message, sends a ranging request message (RNG-REQ), and receives a ranging response message (RNG-RSP). After receiving the ranging response message (RNG-RSP), the idle mode is continued. That is, when the DCD and UCD messages are received and decoded successfully, and when the ranging response message (RNG-RSP) is received, the mobile station enters the period of no paging, thereby performing the idle mode.

FIG. 6 is an exemplary diagram illustrating an operation of a mobile station when using a frame number instead of the DCD / UCD transmission offset shown in Table 14. FIG. When using the DCD / UCD transmission offset, the transmission offset should be at least 16 bits, considering that the idle mode's paging period is at most 16 bits and the DCD / UCD transmission period is at most 10 seconds (= 2000frame, 1frame = 5msec). do. However, in the case of the frame number, even if only the lower 8 bits are used, the DCD / UCD may indicate a frame to be transmitted, thereby reducing the message size.

If a frame number is used instead of the DCD / UCD transmission offset, another example of information that may be included in the TLV form in the paging broadcast message of Table 13 is shown in Table 15.

In case of using a frame number instead of the DCD / UCD transmission offset, another example of the common downlink (Common_DL_Notification_IE) DL-MAP IE of Table 14 is shown in Table 16.

Table 17 shows an example of a broadcast control pointer information element (Broadcast Control Pointer IE) included in a DL-MAP message when using a frame number instead of a DCD / UCD transmission offset.

If the DCD_UCD Configuration Counter value included in the Broadcast Control Pointer IE shown in Table 17 is different from the previous DCD_UCD Configuration Counter value owned by the mobile station, the broadcast station does not change the paging period. After downlink synchronization is performed in the frame indicated by the DCD_UCD Transmission Frame included in the control pointer information element (that is, the MS temporarily awakes in the frame), the DCD and the UCD message transmitted by the base station are received and decoded. After receiving the DCD and UCD messages, the mobile station switches to the non-paging period to perform the idle mode.

On the other hand, if the mobile station fails to decode the DCD or UCD message, or if the base station does not transmit the DCD or UCD message in the frame indicated by the DCD_UCD Transmission Frame value, the mobile station goes down until it receives the updated DCD and UCD message. Link frames must be received and decoded. The mobile station, which has successfully decoded the DCD and UCD messages, switches to the non-paging period and performs idle mode.

As shown in FIG. 6, when DCD / UCD transmission is scheduled for the next paging inactivity period (frame A), the base station transmits a paging broadcast message or a DCD / UCD transmission identifier (DCD / Through the UCD Transmission Indication and the Transmission Offset Bitmap, it is possible to transmit information to the mobile station that the DCD / UCD is transmitted during the next paging period.

In addition, the base station expresses the lower 8 bits of the frame number to be actually DCD / UCD transmission through the DCD transmission frame (UCD Transmission frame) and the UCD transmission frame (UCD Transmission frame), so that the mobile station transmits to the frame even during the paging period Receive a DCD / UCD message.

The DCD Transmission Indication, the UCD Transmission Indication, and the DCD / UCD Transmission Offset Bitmap included in Tables 14 and 16 are 1 bit and 1 bit, respectively. It has a length of 2 bits. Here, the information included in the DCD Transmission Indication, the UCD Transmission Indication, and the DCD / UCD Transmission Offset Bitmap includes one flag having a 2-bit length. Can be represented. Table 18 shows an example of the flag.

As in the example of Table 18, the flag may be used to indicate whether to transmit DCD / UCD during the next paging period. For example, if the value of the flag is '00', it means that DCD / UCD transmission is not scheduled for the next paging period, and if it is '01', it means that only DCD transmission is scheduled. On the other hand, '10' means that only transmission of the UCD is scheduled, and 11 means that transmission is scheduled for both the DCD and the UCD.

On the other hand, even when the mobile station is in the sleep mode, the DCD / UCD can be changed. In this case, according to the present invention, it can be informed that the DCD / UCD has been changed. That is, during the listening interval of the mobile station performing the sleep mode, the base station may transmit information indicating that the DCD / UCD has been changed and information on when the changed DCD / UCD message is transmitted to the mobile station. Meanwhile, even in a sleep interval, the mobile station temporarily switches to a state for receiving a downlink message at the time when the DCD / UCD message is transmitted, and then receives the DCD / UCD message. After receiving the DCD / UCD message, the device returns to a sleep interval, thereby continuing the sleep mode operation.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

1 is an explanatory diagram illustrating an idle mode operation according to a change of a DCD / UCD value.

FIG. 2 is a diagram illustrating an embodiment of a mobile station when a DCD / UCD Indication information is transmitted during a paging period. FIG.

FIG. 3 is a diagram illustrating an operation of a mobile station when transmitting a paging broadcast message or DL-MAP message including DCD / UCD Transmission Offset information. FIG.

4 is a diagram illustrating an embodiment of a mobile station when a paging period and a DCD / UCD message transmission period are matched.

FIG. 5 is a diagram illustrating an exemplary operation of a mobile station when the mobile station in idle mode performs initial ranging as the base station changes coding and modulation schemes. FIG.

FIG. 6 is a diagram illustrating an operation of a mobile station when using a frame number instead of the DCD / UCD transmission offset shown in Table 14. FIG.

Claims (14)

In the method for updating the channel information of the terminal in the power saving mode, Receiving, by the terminal, an information element (IE) including a channel descriptor configuration change counter transmitted in a paging segment and a transmission frame field indicating a frame in which a channel descriptor is transmitted; And If the channel descriptor configuration change counter has changed since the terminal decoded the information element last time, the terminal may specify the channel descriptor in the frame indicated by the transmission frame field, even if the terminal is scheduled for a non-paging period. And keeping awake state for receiving. The method of claim 1, Maintaining a power saving mode prior to receiving the channel descriptors. The method of claim 1, Receiving indication information indicating whether the channel descriptor is scheduled to be transmitted during a next paging unavailable interval. The method of claim 3, wherein And the paging unavailable interval is a period in which communication between a terminal and a base station in a power saving mode is impossible. The method of claim 1, And the information element (IE) is received in a paging segment. The method of claim 5, The paging segment is a channel information update method, characterized in that the communication between the terminal and the base station in the power saving mode. The method of claim 1, The channel descriptor is any one of an uplink channel descriptor (UCD) and a downlink channel descriptor (DCD). The method of claim 7, wherein At least one of the UCD and the DCD is a broadcast message. The method of claim 1, And the information element (IE) is a broadcast control pointer information element (Broadcast Control Pointer IE). The method of claim 1, And wherein the transmission frame field is 8 bits in size and indicates when the next channel descriptor is transmitted. The method of claim 1, And the channel descriptor is a broadcast message. The method of claim 1, The power saving mode is an idle mode (idle mode), characterized in that the channel information update method. The method of claim 1, The power saving mode is a channel information update method, characterized in that the sleep mode (sleep mode). The method of claim 1, Wherein the transmission frame field indicates a frame number.

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