KR101475880B1 - System and method requesting bandwidth allocation - Google Patents

Abstract

The bandwidth allocation requesting system according to the present invention is a bandwidth allocation requesting system between a mobile terminal and a base station, the bandwidth allocation requesting system comprising: a bandwidth allocation requesting system for allocating bandwidth allocation between a mobile terminal and a base station, A bandwidth including the number of allocation failures (F) as the number of frames that fail to allocate bandwidth for the bandwidth allocation request (F), the number of request slots (S) included in one frame, and the total number of mobile terminals A mobile terminal for calculating a number of waiting frames based on the allocation information and transmitting a bandwidth allocation request to the base station after a frame of the number of waiting frames after the second success frame; And a base station for providing the bandwidth allocation information to the mobile terminal, receiving the bandwidth allocation request, and allocating a predetermined slot to the mobile terminal in response to the bandwidth allocation request. Therefore, according to the present invention, each mobile terminal connected to the base station has an opportunity to transmit fair bandwidth request information, and each mobile terminal can achieve the effect of being allocated a fair bandwidth.

Bandwidth allocation request, collision, wait frame

Description

[0001] SYSTEM AND METHOD REQUESTING BANDWIDTH ALLOCATION [0002]

It is a technical field that enables efficient bandwidth allocation of a radio channel of a wireless network.

Specifically, in the case of allocating a bandwidth by allocating a predetermined slot to each mobile terminal by receiving a request through a bandwidth request through a request slot for each frame formed by slots, bandwidth is more effectively allocated .

Particularly, the present invention relates to IEEE 802.16 WiMAX / WiBro technology among wireless network technologies and to competition based bandwidth request technology within IEEE 802.16 networks.

There are four service classes in the bandwidth request allocation mechanisms. In other words,

Unsolicited grant service, real time polling service, non real time polling service, and best effort service.

Here, the best effort service is a service for more flexible applications. And a lottery method. However, since it is a non-guaranteed service, it is generally accepted that competition-based requests are sufficient for best effort services.

Figure 1 illustrates a contention-based bandwidth request allocation process for a best effort traffic channel.

The contention-based bandwidth request process defined in the IEEE 802.16 standard is as follows. Each user terminal connected to one base station transmits bandwidth request information to a base station in a request slot, which is a slot for a predetermined contention-based bandwidth request. Based on the bandwidth request information transmitted without collision, the base station allocates a predetermined slot in the corresponding frame to the user terminal, and allocates the bandwidth to the user terminal. If the bandwidth request information is lost due to collision, the user terminal reduces the collision probability of the next bandwidth request information transmission through Exponential Backoff.

The present invention is for more efficient and fair bandwidth allocation in the case where a plurality of terminals make a bandwidth request with a limited request slot as a bandwidth request.

In general, each user mobile terminal connected to one base station transmits a bandwidth allocation request to a base station in a request slot for a predetermined contention-based bandwidth request for each frame, and transmits a bandwidth allocation request information If the bandwidth allocation request information is lost due to a collision, the user terminal allocates bandwidth to the user terminal through Exponential Backoff without considering the total number of connected terminals. Reduces the collision probability of bandwidth request information transmission.

This method can reduce the overall collision probability, but it operates on the basis of the individual collision experience of each user terminal, which may lead to an unequal bandwidth request information transmission opportunity between each using terminal, which may lead to unequal bandwidth allocation There is a problem.

It is an object of the present invention to solve such a problem.

A bandwidth allocation requesting system according to a first aspect of the present invention is a bandwidth allocation requesting system between a mobile terminal and a base station, the bandwidth allocation requesting system comprising: a first allocation unit (F), the number of requested slots (S) included in one frame, and the total number of mobile terminals (N) connected to the base station, which are the number of frames that fail to allocate bandwidth for the bandwidth allocation request before the success frame, A mobile terminal for transmitting a bandwidth allocation request to the base station after a frame of the number of waiting frames after the second success frame; And a base station for providing the bandwidth allocation information to the mobile terminal, receiving the bandwidth allocation request, and allocating a predetermined slot to the mobile terminal in response to the bandwidth allocation request.

Preferably, the base station comprises: a request receiver for receiving the bandwidth allocation request; A bandwidth allocator for assigning a predetermined slot to the terminal in response to the bandwidth allocation request; And an information generator for generating bandwidth allocation information including at least one of the number of allocation failures, the number of request slots, and the total number of mobile terminals and providing the bandwidth allocation information to the mobile terminal.

In the bandwidth allocation request mobile terminal according to the second aspect of the present invention, the bandwidth for the bandwidth allocation request is smaller than the bandwidth for the bandwidth allocation request after the first success frame, which succeeds in bandwidth allocation after the first success frame, Calculation of the number of waiting frames based on the number of allocation failures (F), the number of unsuccessfully allocated frames, the number of requested slots (S) included in one frame, and the total number of mobile terminals (N) connected to the base station part; And a requesting unit for transmitting a bandwidth allocation request to the base station after a frame of the number of waiting frames after the second success frame.

Preferably, the mobile terminal determines the number of frames that failed in the bandwidth allocation for the bandwidth allocation request after the first success frame succeeding in the bandwidth allocation, An allocation failure count (F), a number of request slots included in one frame (S), and a total number of mobile terminals (N) connected to the base station; A calculating unit for calculating a number of waiting frames based on the number of allocation failures, the number of request slots, and the total number of mobile terminals; And a request unit for transmitting a bandwidth allocation request to the base station after a frame of the number of waiting frames after the second success frame.

Preferably, the requesting unit transmits a bandwidth allocation request to the base station after the frame of the waiting frame number after the second success frame, and transmits a bandwidth allocation request in the adjacent next frame when the bandwidth allocation request fails. can do.

More preferably, the number of idle frames is (number of allocation failures) * (total number of mobile terminals * ln (number of request slots / (number of request slots - 1) - 1}.

A bandwidth requesting method according to a third aspect of the present invention is a bandwidth requesting method between a mobile terminal and a base station, the bandwidth request method comprising the steps of: a first success succeeding in bandwidth allocation, (F), the number of requested slots (S) included in one frame, and the total number of mobile terminals (N) connected to the base station, which are the number of frames that fail to allocate the bandwidth for the bandwidth allocation request before the frame An information collection step in which the mobile terminal collects bandwidth allocation information including the bandwidth allocation information; Calculating a number of idle frames based on the number of allocation failures, the number of request slots, and the total number of mobile terminals; And a bandwidth requesting step in which the mobile terminal transmits a bandwidth allocation request to the base station after a frame of the number of waiting frames after the second success frame.

Preferably, the number N of mobile terminals is received from the base station.

More preferably, the number of waiting frames is (number of allocation failures) * (total number of mobile terminals * ln (number of request slots / (number of request slots - 1) - 1}.

More preferably, the bandwidth requesting step transmits a bandwidth allocation request to the base station after the frame of the waiting frame number after the second success frame, and when the bandwidth allocation request fails, And transmits a bandwidth allocation request in the frame.

According to the present invention, each mobile terminal connected to the base station has an opportunity of transmitting fair bandwidth request information, and each mobile terminal can achieve the effect that the bandwidth is equally allocated.

That is, if bandwidth allocation is successful in a specific frame, by waiting for a predetermined number of frames calculated based on the number of slots, the number of previous bandwidth allocation failures, and the total number of terminals connected to the base station, The bandwidth allocation can be more effectively performed.

A specific embodiment of the present invention will be described with reference to the accompanying drawings.

Figure 2 shows a block diagram of a bandwidth allocation requesting system. FIG. 2 includes a mobile terminal 100 and a base station 300. The mobile terminal 100 includes a calculation unit 170 and a request unit 150. The calculator includes a storage module 110 and a calculation module 130. The base station 300 includes a request receiving unit 310, a bandwidth allocating unit 330, and an information generating unit 350.

The information generating unit 350 of the base station generates the number of frames that failed in the bandwidth allocation for the bandwidth allocation request after the second success frame that succeeds in the bandwidth allocation after the first success frame after the bandwidth allocation succeeds (S) of request slots included in one frame, and the total number (N) of mobile terminals connected to the base station, and transmits the bandwidth allocation information to the mobile terminal.

The terminal receives the bandwidth allocation information from the base station and stores the bandwidth allocation information in the storage module 110. The terminal's calculation module 130 calculates the number of wait frames based on F, S and N. [ However, the bandwidth allocation information may be provided from the base station or may be directly collected by the terminal.

The bandwidth allocation information may be stored in the storage module of the terminal and may be calculated in the calculation module. However, the storage module may be omitted and the bandwidth allocation information may not be stored, Lt; RTI ID = 0.0 > a < / RTI >

The requesting unit 150 waits for the elapse of a frame corresponding to the number of waiting frames after the second success frame in which bandwidth allocation succeeds after the first success frame, and then makes a bandwidth allocation request to the base station.

After waiting for the frames corresponding to the waiting frame, the mobile terminal continuously transmits a bandwidth allocation request until the bandwidth allocation is successful. That is, if the first successful frame in the bandwidth allocation after the second success frame is a third success frame, then after the third success frame, based on the number of unsuccessful bandwidth allocation request transmissions between the second success frame and the third success frame And then calculates the waiting frame again. After the third success frame, the bandwidth allocation request is not transmitted after waiting for the bandwidth allocation request as much as the re-calculated and updated waiting frame. That is, the number of failed bandwidth allocation requests is set to the number of re-allocation failures (F '), and the number of waiting frames is updated again based on F', N, and S. By repeating this process, collision of bandwidth allocation request slots can be remarkably reduced.

If the total number of terminals connected to the base station is N, the number of request slots included in one frame is S, and the number of frames in which the mobile terminal requests bandwidth allocation but fails in the bandwidth allocation request is F, Lt; RTI ID = 0.0 > W,

W = F * N * {ln (S / S-1) -1}, the total number of frames required to succeed in the bandwidth request can be minimized. In the above, W is a real number, but it is possible to approximate it to 0 or a natural number, and it will be a more simple embodiment.

The reason why the total number of frames is reduced by the above formula is as follows.

The probability that the mobile terminal can successfully transmit a bandwidth allocation request in a predetermined frame without collision is referred to as Ps.

Ps = ((S - 1) / S) ^ (N-1)

The estimated number of frames between the first frame succeeding the bandwidth allocation request and the second frame succeeding the bandwidth allocation request is called E (f).

E (f) = 1 / Ps = S / (S - 1)

In the above equations, E (f) for a given S exponentially increases as N increases.

FIG. 5 shows the change of E (f) with respect to N. FIG. When N is 30 and S is 10, each mobile terminal collides 20 or more to make a successful request. As S increases, E (f) decreases. However, when S is 20 (2/3 of N = 30), five collisions still occur for a successful request transmission.

In order to reduce the collision, the number of attempts of the bandwidth allocation request in one frame should be limited. It is assumed that instead of attempting to transmit a bandwidth allocation request every frame, it waits for M frames without transmitting a next bandwidth allocation request after a successful transmission frame of the bandwidth allocation request.

To send a successful bandwidth allocation request, an average of 1 / Ps attempts is required.

The probability that the mobile terminal will attempt to send a bandwidth allocation request in one frame is called Pr.

Pr = (1 / Ps) / (1 / Ps) + m = 1 /

The average number of mobile stations transmitting a bandwidth allocation request in one frame is Nr.

Nr = Pr * N = N / (1 + Ps * m)

Ps = ((S - 1) / S) ^ (Nr - 1) = ((S - 1) / S)

-----[식A]

----- [Formula A]

Since Nr is not deterministic, this approximation can only be assumed on the assumption that S is large enough.

For simplicity, m = k * 1 / Ps. This equation means that one mobile terminal waits for m frames to send the next request, and m is proportional to the number of attempts for a successful request.

Expressing the above formula [A] simply by K,

이고, 따라서,

Lt; / RTI >

Fig. 6 shows the relationship between k and E (f) as n changes. In Fig. 6, s is fixed at 10. When k = 0, it corresponds to Fig. For a reasonable k value, the value of E (f) can be reduced. When N = 30, when each mobile terminal attempts to transmit a bandwidth allocation request when k = 0 in each frame, it takes more than 20 frames to successfully transmit a new bandwidth allocation request. If K = 2, it is reduced to 8 frames.

In order to minimize the number of frames, if k is optimized,

When the above equation is 0,

이며,

Lt;

Since k can not be negative,

이고,

ego,

이다.

to be.

That is, when the number of requested slots is less than e ^ (1 / N) / {e ^ (1 / N) -1}, (number of allocation failures) * {total number of mobile terminals * ln (1 / N) -1}, if the number of request slots is larger than e (1 / N) / {e (1 / N) -1} It may be desirable that there is no need to do so.

Fig. 7 shows the relationship between N and E (f). Compared with FIG. 6, it can be seen that the number of frames is greatly reduced when S = 20.

FIG. 3 shows a block diagram of another embodiment of a bandwidth allocation requesting system according to the present invention. That is, the mobile terminal 200 includes the count unit 205, counts the number of request slots included in the frame, and counts the number of times that the bandwidth allocation request fails. The total number of mobile terminals connected to the base station 300 is preferably detected by the information generating unit 350 of the base station and transmitted to the mobile terminal. Of course, it is also preferable that the number of requested slots included in one frame is also received in advance from the base station.

That is, compared with the embodiment of FIG. 2, the mobile terminal detects and generates the slot information constituting the frame without transmitting it to the base station, and the mobile terminal itself counts the number of times that the transmission of the bandwidth allocation request failed due to the collision There is a difference to generate.

FIG. 4 shows a flowchart of an embodiment of a bandwidth allocation request method according to the present invention.

That is, the number of allocation failures (F), which is the number of frames that failed in bandwidth allocation for a bandwidth allocation request before the second success frame that succeeds in bandwidth allocation after the first success frame after the first successful frame succeeding in bandwidth allocation, (S) of request slots included in one frame and a total number (N) of mobile terminals connected to the base station.

(S102) in which the mobile terminal calculates the number of wait frames based on the F, S, and N. [

A bandwidth requesting step (S103) of transmitting a bandwidth allocation request to the base station after waiting for the elapse of a frame corresponding to the number of waiting frames after a second success frame in which the mobile terminal first succeeds in bandwidth allocation after the first success frame, .

A bandwidth allocation request mobile terminal comprising:

An allocation failure count (F), which is the number of frames that failed in bandwidth allocation for a bandwidth allocation request before a second success frame that succeeds in bandwidth allocation after the first success frame since the first successful frame succeeding bandwidth allocation, (S) of the request slots included in the frame and the total number of mobile terminals (N) connected to the base station, and after the frame of the number of waiting frames after the second success frame And includes a terminal that transmits a bandwidth allocation request to the base station,

According to the present invention, each mobile terminal connected to the base station has an opportunity to transmit fair bandwidth request information, and each mobile terminal can achieve the effect of being allocated a fair bandwidth.

Accordingly, the present invention has industrial applicability useful in the field of wireless mobile communication.

Figure 1 illustrates a contention-based bandwidth request allocation process for a best effort traffic channel.

FIG. 2 shows a block diagram of a bandwidth request allocation system according to the present invention.

3 shows a block diagram of another embodiment of a bandwidth request allocation system according to the present invention.

4 is a block diagram of a bandwidth request allocation method according to the present invention.

5 is a graph showing the number of frames required for bandwidth request success.

6 is a graph showing E (f) according to the change of k when k = Ps * m.

7 is a graph showing E (f) according to the change of N when S is fixed.

DESCRIPTION OF THE EMBODIMENTS

100: mobile terminal 110: storage module

130: calculation module 150:

170:

300: base station 310: request receiver

330: bandwidth allocation unit 350: information generation unit

205: counting unit 200: base station

Claims (10)

A system for requesting bandwidth allocation between a mobile terminal and a base station, An allocation failure count (F), which is the number of frames that failed in bandwidth allocation for a bandwidth allocation request before a second success frame that succeeds in bandwidth allocation after the first success frame since the first successful frame succeeding bandwidth allocation, (S) of request slots included in a frame and a total number (N) of mobile terminals connected to the base station, and calculates the number of waiting frames after the second success frame A mobile terminal for transmitting a bandwidth allocation request to the base station after a lapse of a corresponding frame; And And a base station for providing the bandwidth allocation information to the mobile terminal, receiving the bandwidth allocation request, and allocating a predetermined slot to the mobile terminal in response to the bandwidth allocation request. The method according to claim 1, The base station comprises: A request receiver for receiving the bandwidth allocation request; A bandwidth allocator for assigning a predetermined slot to the terminal in response to the bandwidth allocation request; And And generating an bandwidth allocation information including at least one of the number of allocation failures, the number of request slots, and the total number of mobile terminals, and providing the bandwidth allocation information to the mobile terminal. A mobile terminal for requesting bandwidth allocation, An allocation failure count (F), which is the number of frames that failed in bandwidth allocation for a bandwidth allocation request before a second success frame that succeeds in bandwidth allocation after the first success frame since the first successful frame succeeding bandwidth allocation, A calculating unit for calculating a number of waiting frames based on the number of request slots (S) included in the frame and the total number of mobile terminals (N) connected to the base station; And a requesting unit for transmitting a bandwidth allocation request to the base station after waiting for the elapse of a frame corresponding to the number of waiting frames after the second success frame. The method of claim 3, The calculating unit calculates, An allocation failure count (F), which is the number of frames that failed in bandwidth allocation for a bandwidth allocation request before a second success frame that succeeds in bandwidth allocation after the first success frame since the first successful frame succeeding bandwidth allocation, A storage module for storing bandwidth allocation information including a number S of request slots included in a frame and a total number N of mobile terminals connected to the base station; And a calculation module for calculating a number of waiting frames based on the number of allocation failures, the number of request slots, and the total number of mobile terminals. The method of claim 3, Wherein the requesting unit transmits a bandwidth allocation request to the base station after the frame of the waiting frame number after the second success frame and transmits a bandwidth allocation request in a next adjacent frame when the bandwidth allocation request fails. Mobile terminal. The method of claim 3, The number of waiting frames is If the number of requested slots is smaller than e (1 / N) / {e (1 / N) -1} (Number of allocated slots) * {total number of mobile terminals * ln (number of request slots / (number of request slots - 1)) - 1}. A method for requesting bandwidth allocation between a mobile terminal and a base station, An allocation failure count (F), which is the number of frames that failed in bandwidth allocation for a bandwidth allocation request before a second success frame that succeeds in bandwidth allocation after the first success frame since the first successful frame succeeding bandwidth allocation, An information collection step in which the mobile terminal collects bandwidth allocation information including a number S of requested slots included in a frame and a total number N of mobile terminals connected to the base station; Calculating a number of idle frames based on the number of allocation failures, the number of request slots, and the total number of mobile terminals; And And a bandwidth requesting step of the mobile terminal transmitting a bandwidth allocation request to the base station after waiting for the elapse of a frame corresponding to the number of waiting frames after the second success frame. 8. The method of claim 7, Wherein the number N of mobile terminals is received from the base station. 8. The method of claim 7, The number of waiting frames may be, If the number of requested slots is smaller than e (1 / N) / {e (1 / N) -1} (Number of allocation failure times) * {total number of mobile terminals * ln (number of request slots / (number of request slots - 1)) - 1}. 8. The method of claim 7, Wherein the bandwidth requesting step transmits a bandwidth allocation request to the base station after a frame of the waiting frame number after the second success frame and allocates a bandwidth allocation request in a next frame adjacent to the frame in which the bandwidth allocation request is transmitted, And transmitting the bandwidth allocation request message.

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