KR20090063958A - Method for selecting frequency assignment in broadband wireless access system and method for requesting uplink bandwidth using the same - Google Patents

Abstract

A FA selection method for maximizing the performance of an uplink bandwidth request to a base station from a terminal and uplink bandwidth request method using the same are provided to minimize the loss of the message transmitting an uplink bandwidth request. A terminal extracts the value of NI as an uplink noise/interference level information element extracted by FA(Frequency Assignment)(S110). An RSSI(Received Signal Strength Indicator)/NI value is calculated based on the NI value corresponding to each FA about all FAs(S120). The terminal determines whether the paper in which it is necessary to have message transmission for an uplink band request(S130). The FA having the terminal is the calculated received signal strength indicator for each FA/NI value(S140).

Description

Method for selecting a FA in a broadband wireless access system and a method for requesting an uplink band using the same {METHOD FOR SELECTING FREQUENCY ASSIGNMENT IN BROADBAND WIRELESS ACCESS SYSTEM AND METHOD FOR REQUESTING UPLINK BANDWIDTH USING THE SAME}

The present invention relates to an uplink band request method in a broadband wireless access system. In particular, the present invention relates to a method for selecting a frequency assignment (FA) in a broadband wireless access system supporting frequency overlay and an uplink band request method using the same.

The broadband wireless access system defines a terminal (MS), a base station (BS) and a router (ACR) to be compatible with the existing public IP network, and grants the technology to allow the terminal to have mobility. It is a system that enables the use of IP-based network services on the move. The existing broadband wireless access system provides a structure in which one terminal can communicate with a base station only through a band belonging to one FA.

On the other hand, as an evolved form of such a conventional broadband wireless access system, a broadband wireless access system of an advanced concept has been proposed in which one terminal can communicate with a base station through a plurality of FAs. Here, a function of allowing a terminal to communicate with a base station using a plurality of FAs is called a frequency overlay function. According to this advanced concept of broadband wireless access system (hereinafter referred to as "frequency overlay communication system"), the base station is connected to a public IP network, the existing broadband wireless access system (hereinafter referred to as "non-frequency overlay communication system") While having the same structure as, the radio access portion between the base station and the terminal is different from the non-frequency overlay communication system. That is, there is a difference that the base station and the terminal can communicate with each other through a plurality of frequency bands connected by using two or more FAs. The advantage of the frequency overlay communication system having such a feature is that by modifying only the radio access method between the terminal and the base station and its related MAC layer functions, N times compared to the non-frequency overlay communication system (one terminal uses two FAs). You can use twice the bandwidth under the assumption, and consequently, you can use the bandwidth of the terminal increases in proportion to the number of FAs used by the terminal, which doubles the transmission speed between the terminal and the base station. An abnormal increase (in general, when the number of FAs used between the UE and the base station is N, the transmission rate is increased by N times compared to a non-frequency overlay communication system using one FA).

Meanwhile, when a terminal needs to transmit data to a base station in a frequency overlay communication system or a non-frequency overlay communication system, the terminal requires an uplink band for transmitting uplink data to the base station, and the base station uplink from the terminal. By allocating an uplink band capable of transmitting uplink data in response to a band request, the terminal can transmit uplink data to the base station through an uplink band allocated from the base station.

In this case, in the non-frequency overlay communication system, since the terminal and the base station communicate using only one FA, an uplink band request occurs through one FA. However, in the frequency overlay communication system, since the terminal and the base station communicate using a plurality of FAs, an uplink band request may occur through all the FAs used by the terminal. In particular, when a terminal transmits data to a base station through a connection established for transmission of data traffic, that is, a traffic connection between the terminal and the base station, an uplink bandwidth request is frequently generated between the terminal and the base station. . In this case, since the terminal may request the uplink band from the base station through all the FAs, the performance of the uplink band request depends on the channel status of each FA used between the terminal and the base station. In particular, when a lot of uplink bandwidth request is generated through FA having a poor channel condition, there is a problem that the performance of the uplink bandwidth request may be degraded due to frequent loss of a message transmitted from a terminal to a base station.

An object of the present invention is to provide a FA in a broadband wireless access system capable of maximizing the performance of the uplink bandwidth request by minimizing the loss of a message to be transmitted when the uplink band request from the terminal to the base station in the frequency overlay communication system. It is to provide a selection method and an uplink bandwidth request method using the same.

FA selection method according to one feature of the present invention for achieving the above object,

A method for selecting a FA having the best wireless transmission channel state among FAs used in a terminal of a broadband wireless access system,

a) each terminal receiving a DL MAP from the base station via a plurality of FAs being used for a frequency overlay function with the base station; b) extracting noise and interference levels of a wireless transmission channel existing on each FA from the DL MAP and estimating a state of the wireless transmission channel for each FA; And c) selecting the FA having the best state of the radio transmission channel based on the estimated state of the radio transmission channel for each FA.

According to another aspect of the present invention, a method for requesting an uplink band is provided.

A method for requesting an uplink band from a terminal of a broadband wireless access system to a base station,

a) each terminal estimating a state of a radio transmission channel for a plurality of FAs being used for a frequency overlay function with a base station; b) when the uplink data traffic to be transmitted to the base station is generated, selecting an FA having the best state of the radio transmission channel based on the estimated state of the radio transmission channel for each FA; And c) transmitting a message for an uplink band request to the base station through an FA having the best state of the selected radio transmission channel and allocating an uplink bandwidth from the base station.

According to the present invention, the FA having the best state of the wireless transmission channel can be selected from among the FAs being used by the terminal.

In addition, since the terminal may perform the uplink band request procedure by selecting the FA having the best state of the wireless transmission channel among the FAs being used, the probability of the loss of the message to be transmitted for the uplink band request can be minimized. .

In addition, since the loss of the message to be delivered for the uplink band request can be minimized, the performance of the uplink band request from the terminal to the base station can be maximized.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. .

In the present specification, a terminal (MS) is a mobile station (MS), a terminal (terminal), a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), It may refer to a user equipment (UE), an access terminal (AT), or the like, and may include all or a part of functions of a mobile terminal, a subscriber station, a portable subscriber station, a user device, and the like.

In the present specification, a base station (BS) is an access point (AP), a radio access station (Radio Access Station, RAS), a Node B (Node B), a base transceiver station (Base Transceiver Station, BTS), MMR ( Mobile Multihop Relay) -BS and the like, and may include all or part of functions such as an access point, a radio access station, a Node B, a base transceiver station, and an MMR-BS.

Now, a method for requesting an uplink band in a broadband wireless access system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram schematically illustrating a general non-frequency overlay communication system.

As shown in FIG. 1, in a non-frequency overlay communication system, a base station (BS) 10 is connected to a specific operator's IP network 30 through a router ACR 20. Therefore, in order for the subscriber to use the IP-based service through the terminal MS 40, the subscriber needs to access the public IP network 50 through the base station 10, the router 20, and the operator network 30. .

In addition, an AAA server 60, an ASA server 70, an HA server 80, and the like exist in the operator IP network 30. The AAA server 60 and the ASA server 70 use the terminal 40. To store authentication and QoS information for the subscriber who wants to access the non-frequency overlay communication system, and the HA server 80 performs a home agent function for the terminal 40.

In such a non-frequency overlay communication system, the terminal 40 can use IP-based network services while moving through the base station 10, the router 20, and the operator IP network 30. However, in such a non-frequency overlay communication system, the terminal 40 can communicate with the base station 10 only through one FA.

In order to solve this drawback, a frequency overlay communication system has been proposed that provides a frequency overlay function, which is a function for allowing a terminal and a base station to communicate through a plurality of FAs. In this frequency overlay communication, the structure between the base station 10 and the public IP network 50 is the same as that of the conventional non-frequency overlay communication system, but because the structure between the base station 10 and the terminal 40 is different, it is different here. Only the parts are explained.

2 is a diagram schematically illustrating a wireless access method between a terminal and a base station in a general frequency overlay communication system.

As shown in FIG. 2, the base station 11 in the frequency overlay communication system may communicate with the frequency overlay capable terminal 41 capable of performing the frequency overlay function using a plurality of FAs.

As described above, in the frequency overlay communication system, the base station 11 and the terminal 41 can communicate through a plurality of FAs, but in FIG. 2, only two FAs FA # 1 and FA # 2 are used for convenience of description. It is assumed to be described.

Referring to FIG. 2, the terminal 41 communicates with the base station 11 using two FAs FA # 1 and FA # 2. That is, the terminal 41 may communicate with the base station 11 through the 10 MHz band of one FA (FA # 1) and the 10 MHz band of the other FA (FA # 2).

Thus, in this case, the terminal 41 can use twice the bandwidth of the terminal 40 in the non-frequency overlay communication system shown in FIG. 1, thereby transmitting between the terminal 41 and the base station 10. Speed can also be increased approximately twice.

3 is a flowchart of an uplink bandwidth request method in a general broadband wireless access communication system.

Referring to FIG. 3, when data traffic to be transmitted from the terminal 41 to the base station is generated, the terminal 41 needs to transmit a message for uplink bandwidth request. Bandwidth Request Code (BR Code) is transmitted (S10).

When the base station 11 receives the bandwidth request code from the terminal 41, the terminal 41 includes a UL MAP (UL MAP with CDMA) including a CDMA allocation information element containing uplink bandwidth information for transmitting the bandwidth request message. allocation IE) is transmitted to the terminal 41 (S11).

Accordingly, the terminal 41 detects the CDMA allocation information element included in the UL-MAP message including the CDMA allocation information element received from the base station 11, and the uplink resource included in the CDMA allocation information element, That is, a bandwidth request header (BR header), which is a bandwidth request message, is transmitted to the base station 11 using the uplink bandwidth (S12). At this time, the terminal 41 includes a basic connection identifier (Basic Connection Identifier: Basic CID) uniquely allocated through an initial ranging procedure with the base station 11 in the bandwidth request header to request a bandwidth including the basic connection identifier. A header (BR header with Basic CID) is transmitted to the base station 11.

Next, the base station 11 generates a UL-MAP allocated an uplink bandwidth for transmission of uplink data traffic of the terminal 41 through the bandwidth request header received from the terminal 41, and then sends it to the terminal 41. In step S13, the terminal 41 transmits uplink data traffic to the base station 11 using the uplink bandwidth allocated to the UL-MAP received from the base station 11 (S14). In this case, since the base station 11 receives the bandwidth request header having the basic connection identifier in step S30, the base station 11 allocates an uplink bandwidth to the corresponding basic connection identifier in step S40. The UL-MAP to which the uplink bandwidth is allocated is also transmitted to the terminal 41 having the corresponding basic connection identifier.

Meanwhile, FIG. 3 illustrates a process in which a terminal transmits data by requesting an uplink band to a base station through a traffic connection when only one FA is used in a broadband wireless access system. However, the terminal and the base station communicate through a plurality of FAs. In a frequency overlay communication system capable of performing the terminal, the terminal may request an uplink band to the base station through all FAs used by the terminal.

4 is a flowchart of an uplink band request method in a conventional frequency overlay communication system.

2 and 4, in the conventional frequency overlay communication system as shown in FIG. 2, the terminal 41 communicates with the base station 11 using two FAs FA # 1 and FA # 2. Is doing. That is, the terminal 41 and the base station 11 have one connection through FA # 1 and another connection through FA # 2.

In this state, when the terminal 41 needs to request an uplink band, the terminal 41 transmits uplink data by performing a procedure as shown in FIG. 3 with the base station 11 through FA # 2. Bandwidth may be allocated (S20 to S23).

As described above, in the conventional frequency overlay communication system, since the terminal may request the uplink band from the base station through all the FAs, the performance of the uplink band request depends on the channel state of the FAs used between the terminal and the base station. In particular, when a lot of uplink bandwidth request is generated through FA having a poor channel condition, there is a problem that the performance of the uplink bandwidth request may be degraded due to frequent loss of a message transmitted from a terminal to a base station.

Accordingly, in an embodiment of the present invention, when the terminal requests an uplink band for transmitting uplink data traffic from the terminal to the base station, the FA having the best channel state among the FAs used between the base stations is selected. To perform the uplink band request. Particularly, in the embodiment of the present invention, when a traffic connection established for transmission of data traffic is established between a terminal and a base station, an uplink band through a traffic connection is performed by performing an uplink band request through an FA having the best channel state. Improve performance of demand

5 is a flowchart illustrating a FA selection method in a terminal according to an embodiment of the present invention.

With reference to FIG. 5, the FA classification in the frequency overlay communication system will be described before describing an uplink band request method according to an embodiment of the present invention.

In a frequency overlay communication system, a base station and a terminal may communicate using a plurality of FAs. At this time, a specific FA is designated as a primary frequency assignment (pFA) among the FAs used, and all other FAs are sFA (secondary). Frequency Assignment). Therefore, only one pFA and more than one sFA may exist between a specific terminal and a base station in a frequency overlay communication system. Here, pFA is not only used for transmitting most of the important control signals between the base station and the terminal, but also used for transmitting data traffic between the two. On the other hand, sFA is a FA mainly used for data traffic transmission, and the control signal is transmitted at a considerably lower frequency than pFA. In addition, if the connection through the pFA is not established and maintained between the base station and the terminal, the base station and the terminal is in a disconnected state, but if the connection through the pFA, even if the connection setup through the sFA is disconnected, the base station and the terminal The connection for intercommunication is maintained. As described above, in the frequency overlay communication system, a plurality of FAs exist in the same base station, and these FAs are divided into pFAs and sFAs, but have different functions and meanings as described above. In particular, pFA plays a very important role in the communication between the base station and the terminal.

Referring to FIG. 2, if FA # 1 is determined as pFA while the base station 11 and the terminal 41 are communicating through a total of two FAs, the remaining FA # 2 will be sFA. Therefore, if FA # 1 is disconnected because FA # 1 is pFA, the connection between the base station 11 and the terminal 41 is released. However, since FA # 2 is sFA, the connection through FA # 1 is lost even if FA # 2 is disconnected. If maintained, the connection between the base station 11 and the terminal 41 can be maintained.

Hereinafter, an uplink band request method according to an embodiment of the present invention will be described with reference to FIGS. 2 and 5.

First, the terminal 41 receives a DL MAP transmitted from the base station 11 through all FAs in use, and the UL noise and interference level information element existing for each received DL MAP. A MAP IE called level information element) is extracted (S100). The uplink noise and interference level information element is used by the base station 11 to determine the transmission power of the uplink data symbol to be transmitted by the terminal 41 when the open loop power control mode is used in the broadband radio access system. It is a MAP IE to notify the terminal 41 through. In addition, even if the terminal 41 is using the closed loop power control mode, this uplink noise and interference level information element is continuously notified from the base station 11 to the terminal 41.

The uplink noise and interference level information element includes information called NI. Here, NI is a measure of the degree of noise and interference of the radio transmission channel present on the FA on which the corresponding DL MAP is transmitted. The smaller the value of the NI, the better the noise and interference characteristics of the FA, that is, the radio transmission characteristics of the FA channel. Since a specific method for transmitting the uplink noise and interference level information element including the NI to the terminal 41 through the DL MAP is well known, a detailed description thereof will be omitted here.

Accordingly, the terminal 41 extracts values of NI included in all uplink noise and interference level information elements extracted for each FA (S110).

Next, the terminal 41 calculates RSSI (Received Signal Strength Indicator) / NI values for all FAs being used by the terminal 41 based on the NI values corresponding to the respective FAs (S120). Here, RSSI represents the received signal strength, and is a measure of the strength of the signal received by the terminal 41 through the wireless transmission channel on a specific FA. Omit.

As such, the RSSI / NI value calculated in step S120 indicates a radio transmission characteristic of the corresponding FA. The larger the value, the relatively better the radio transmission channel state of the corresponding FA.

Subsequently, the terminal 41 determines whether there is data traffic that needs to be transmitted through the uplink, so that message transmission for the uplink band request is necessary (S130).

If the terminal 41 determines that a message transmission for an uplink band request is necessary, the terminal 41 selects an FA having the largest value among the RSSI / NI values for each FA calculated in the step S120 (S120). S140). The FA selected in this way indicates that the radio transmission channel state is the best FA among the FAs used by the terminal 41.

Accordingly, the terminal 41 performs a procedure for uplink band request through the FA selected in step S140 (S150).

As such, the terminal 41 may determine the FA having the best wireless transmission channel state among the FAs in use through the steps S100 to S150, by using the wireless channel of the best state determined as described above. A message transfer procedure required for uplink bandwidth request may be performed. Accordingly, the terminal 41 can always deliver the message for the uplink band request by using the FA having the radio channel of the best state which can be selected by itself, thereby minimizing the possibility of the loss of the message transmitted to the base station 11. This can improve the performance of uplink bandwidth requirements using traffic connections.

Hereinafter, an uplink band request method according to an embodiment of the present invention will be described with reference to FIG. 6.

As described with reference to FIG. 5, the base station 11 and the terminal 41 communicate with each other through two FAs. One of the two FAs used for communication is pFA and one is sFA. For example, FA # 1 of the base station 11 and FA # 1 of the terminal 41 are pFAs, and FA # 2 of the base station 11 and FA # 2 of the terminal 41 are sFAs.

Therefore, the base station 11 and the terminal 41 communicate with each other through the FA # 1 operating as pFA and control signals and data, and communicate with each other via FA # 2 operating as sFA. Is doing.

In this state, the terminal 41 receives DL MAPs transmitted by the base station 11 through respective FAs, i.e., pFA and sFA (S200, S200 '). As described above, the DL MAP includes a MAP IE called UL Noise and Interference Level Information Element.

Accordingly, the terminal 41, as described with reference to FIG. 5, the NI value from the uplink noise and interference level information elements included in the DL MAP received in the pFA and sFA through the steps (S200, S200 '), respectively. After calculating the RSSI / NI value for each pFA and sFA by extracting the extracted, select the FA having a larger RSSI / NI value among the pFA and sFA (S210).

FIG. 6 illustrates a case where pFA is selected because the RSSI / NI value of the pFA is greater than the RSSI / NI value of the sFA in step S210 and it is determined that the radio transmission channel state of the pFA is better than the radio transmission channel state of the sFA. One drawing. That is, the uplink band request process as described in FIG. 3 is performed through the selected pFA because the radio transmission channel state is better.

Accordingly, the terminal 41 transmits a bandwidth request code (BR Code) to the base station 11 through the pFA selected in step S210 (S220), and includes a UL- containing CDMA allocation information element from the base station 11. A MAP message is received (S230).

Thereafter, the terminal 41 transmits a bandwidth request message (BR header), which is a bandwidth request message, to the base station 11 by using the uplink bandwidth included in the CDMA allocation information element received in step S230 (see FIG. S240). At this time, the terminal 41 is assigned during the Dynamic Service Addition (DSA) process with the base station 11, the traffic connection identifier (Transport CID) used for the service-specific classification of data traffic in the bandwidth request header It includes and transmits to the base station 11.

Next, the base station 11 generates a UL-MAP to which the uplink bandwidth for the transmission of the uplink data traffic of the terminal 41 through the bandwidth request header received from the terminal 41 and then to the terminal 41. Transmit (S250). Accordingly, the terminal 41 may transmit uplink data traffic to the base station 11 using the uplink bandwidth allocated to the UL-MAP received from the base station 11.

Meanwhile, in step S210, if the RSSI / NI value of the sFA is greater than the RSSI / NI value of the pFA, it is determined that the radio transmission channel state of the sFA is better than the radio transmission channel state of the pFA, so that the sFA is selected. The bandwidth request process must be done through the sFA, which is shown in FIG.

Since the uplink band request method shown in FIG. 7 is the same as the processes S200 to S250 shown in FIG. 6 except that the band request processes S320 to S350 are performed through sFA instead of pFA, the method shown in FIG. The case may be easily understood, so detailed description is omitted here.

As described above, in the embodiment of the present invention, the FA having a good radio transmission channel state may perform an uplink band request process even without distinguishing between pFA and sFA.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a diagram schematically illustrating a general non-frequency overlay communication system.

2 is a diagram schematically illustrating a wireless access method between a terminal and a base station in a general frequency overlay communication system.

3 is a flowchart of a method for requesting an uplink band in a general broadband wireless access communication system.

4 is a flowchart of an uplink band request method in a conventional frequency overlay communication system.

5 is a flowchart illustrating a FA selection method in a terminal according to an embodiment of the present invention.

6 is a flowchart illustrating an example of an uplink band request method according to an embodiment of the present invention.

7 is a flowchart illustrating another example of an uplink band request method according to an embodiment of the present invention.

Claims (9)

In the method for selecting the FA having the best wireless transmission channel state among the FA (Frequency Assignment) in use in the terminal of the broadband wireless access system, a) each terminal receiving a DL MAP from the base station via a plurality of FAs being used for a frequency overlay function with the base station; b) extracting noise and interference levels of a wireless transmission channel existing on each FA from the DL MAP and estimating a state of the wireless transmission channel for each FA; And c) selecting the FA having the best state of the radio transmission channel based on the estimated state of the radio transmission channel for each FA; FA selection method comprising a. The method of claim 1, Step b), Extracting uplink noise and interference level information elements in DL MAP received from the base station through the respective FAs; Extracting NI values from the uplink noise and interference level information elements extracted for each FA; And Estimating a state of a wireless transmission channel for each FA by calculating a value obtained by dividing a received signal strength indicator representing the strength of a signal received for each FA by the NI value extracted in the step. FA selection method comprising a. The method of claim 2, In step c), the FA selection method is characterized in that the FA having the largest value is selected as the FA having the highest value by comparing the values obtained by dividing the received signal strength by the NI value for each FA. . A method for requesting an uplink band from a terminal of a broadband wireless access system to a base station, a) each terminal estimating a state of a radio transmission channel for a plurality of FAs being used for a frequency overlay function with a base station; b) when the uplink data traffic to be transmitted to the base station is generated, selecting an FA having the best state of the radio transmission channel based on the estimated state of the radio transmission channel for each FA; And c) transmitting an uplink bandwidth request message to the base station through an FA having the best state of the selected wireless transmission channel, and allocating an uplink bandwidth from the base station; Uplink band request method comprising a. The method of claim 4, wherein Step a) is Extracting uplink noise and interference level information elements in DL MAP received from the base station through the respective FAs; Extracting NI values from the uplink noise and interference level information elements extracted for each FA; And Estimating a state of a wireless transmission channel for each FA by calculating a value obtained by dividing a received signal strength representing the strength of a signal received for each FA by the NI value extracted in the step. Uplink band request method comprising a. The method of claim 5, B), Determining whether there is uplink data traffic to transmit to the base station; And If it is determined that the uplink data traffic is present, the FA having the highest value is selected as the FA having the highest state by comparing the received signal strength divided by the NI value for each FA. step Uplink band request method comprising a. The method according to any one of claims 4 to 6, i) transmitting a bandwidth request code (BR code) to the base station via FA having the best status of the selected wireless transport channel; ii) receiving a UL MAP including a CDMA allocation information element from the base station via FA with the best state of the selected wireless transport channel; iii) transmitting a bandwidth request header (BR header) to the base station using an uplink bandwidth included in the CDMA allocation information element on the FA having the best status of the selected radio transmission channel; And i) receiving a UL MAP including an uplink bandwidth for uplink data traffic from the base station through the FA having the best state of the selected radio transmission channel; Uplink band request method comprising a. The method of claim 7, wherein The bandwidth request header transmitted to the base station in step iii) and the UL MAP received from the base station in step iv) include a traffic connection identifier (Transport CID) used for service classification of the uplink data traffic. Uplink band request method, characterized in that there is. The method according to any one of claims 4 to 6, After step c), Transmitting the uplink data traffic to the base station using the uplink bandwidth allocated from the base station The uplink band request method further comprising.

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