JP4756592B2 - Base station, terminal device, information source device, and communication method - Google Patents

Description

  The present invention relates to a base station such as a wireless LAN, a terminal device, and a communication method.

In general, it is desired to efficiently use a bandwidth that is a communication resource during communication.
For example, in Patent Document 1, in a cellular communication system, the priority of transmission data is added to the downlink channel quality, communication resource allocation to each communication device is determined, and QoS (Quality of Service) control is followed. Data transmission is disclosed.
Japanese Patent Laid-Open No. 2002-7802 Dimitrios Stiliadis and Anujan Varma, `` Latency-Rate Servers: A General Model for Analysis of Traffic Scheduling Algorithms '', IEEE / ACM TRANSACTIONS ON NETWORKING, VOL.6, NO.5, OCTOBER 1998

Here, in actual bandwidth allocation, the problem is how much traffic is generated, that is, how much the burstiness of information is.
In other words, in the case of variable transmission rate traffic, even if the average transmission rate μ is low, the transmission rate may increase instantaneously, and transmission delay and packet loss will occur unless the bandwidth is expanded accordingly. is there.

  In this regard, in the technique of Patent Document 1, priority information is only added to transmission data input from the upper layer to the base station, and the base station allocates communication resources according to the priority information. I'm just there. Patent Document 1 does not disclose anything about how to effectively determine the bandwidth to be allocated when the transmission rate of transmission data varies.

  Therefore, an object of the present invention is to provide a new technical means for efficiently performing bandwidth allocation.

[base station]
The present invention is a base station that can communicate with a terminal device, and a computing unit that calculates an allocated bandwidth for a transmission queue provided for each type of transmission information in the base station and / or the terminal device, and transmission when a bandwidth is given A parameter capable of calculating a maximum transmission delay amount of information and an acquisition unit for acquiring a maximum allowable transmission delay amount of the transmission information, and the calculation unit includes the parameter of each transmission information and the maximum allowable transmission of each transmission information. A bandwidth allocated to each transmission queue is calculated based on the delay amount.

  According to the present invention, the base station that allocates a bandwidth to the transmission queue of the base station and / or the terminal device can determine the parameter that can calculate the maximum transmission delay amount of the transmission information when the bandwidth is given and the maximum permissible transmission information. Using the transmission delay amount, it is possible to calculate the allocated bandwidth to each transmission queue so that the maximum transmission delay amount of the transmission information when a certain band is allocated is less than or equal to the maximum allowable transmission delay amount of the transmission information. it can.

Moreover, it is preferable that the parameter represents traffic of transmission information based on a model that absorbs traffic fluctuation. As the model, for example, a token bucket model can be adopted.
The parameters include, for example, an upper limit on the amount of information transmitted from the information source at a time, an upper limit on the amount of information transmitted from the information source in a short period of time, and a transmission rate over a long period of information transmitted from the information source. If the upper limit is included, the maximum transmission delay amount can be calculated.

The arithmetic unit preferably calculates the bandwidth so that the sum of the bandwidths of the transmission queues is minimized under the following constraint conditions. If there is a difference between the allocated bandwidth and the effective bandwidth, the bandwidth calculated here is preferably the effective bandwidth, but may be the allocated bandwidth.
Condition 1: DB _{i, max} ≧ σ _i / r _i + Θ _i −L _{i, max} / r _i
Condition 2: r _i ≧ ρ _i
However,
i: Information source (1 to n: n is the number of information sources)
DB _{i, max} : Maximum allowable transmission delay amount of transmission information from information source i σ _i : Upper limit of information amount transmitted from information source i in a short period r _i : Bandwidth of transmission queue corresponding to information source i Θ _i : Delay time from the occurrence of traffic in the information source i to actual transmission L _{i, max} : Upper limit of the amount of information transmitted from the information source i at a time ρ _i : Over a long period of information transmitted from the information source i Maximum transmission rate

The calculation unit calculates an effective bandwidth that can be actually used for transmission of each transmission information based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information, and sets a bandwidth larger than the effective bandwidth to a transmission queue. It is preferable to calculate the bandwidth allocated to
When the effective band is smaller than the allocated band, the maximum transmission delay amount viewed from the effective band is larger than the maximum transmission delay amount viewed from the allocated band. For this reason, the calculation unit makes the band calculated based on the parameter and the maximum allowable transmission delay amount an effective band, and uses a larger band as the allocated band, thereby ensuring that the transmission delay is the maximum allowable transmission delay amount. It becomes as follows.

  It is preferable that the calculation unit adds the bandwidth for transmitting at least the overhead necessary for transmitting the transmission information to the calculated effective bandwidth to obtain the allocated bandwidth. In this case, even if overhead is added to the transmission information, the transmission delay is surely less than the maximum allowable transmission delay amount.

The base station preferably performs communication by a communication method in which an allocated bandwidth r _i ′ to a transmission queue corresponding to the information source i is defined by the following equation.
r _i ′ = ((TXOP _i + Δ _i ) / SI) × R _j
However,
TXOP _i : Transmission opportunity of information source i [sec]
Δ _i : Overhead [sec] necessary for transmitting information of information source i
SI: Service interval [sec]
R _j : Physical rate of transmission channel [bit / sec]
(J: 1 to K: K is the number of terminal devices)

  It is preferable that the arithmetic unit adds the bandwidth for transmitting at least the upper limit amount of information transmitted at a time from the information source to the calculated effective bandwidth to obtain the allocated bandwidth. Depending on the communication method, the upper limit of the amount of information transmitted at one time from the information source is wasted, and the effective bandwidth is reduced accordingly. If a band for transmitting the upper limit amount of information transmitted at one time is added, an appropriate allocated band is obtained.

The base station preferably performs communication by a communication method in which the allocated bandwidth r _i ′ of the transmission queue corresponding to the information source i is defined by the following equation.
r _i ′ = ((TXOP _i + (L _{i, max} / R _j )) / SI) × R _j
However,
TXOP _i : Transmission opportunity of information source i [sec]
SI: Service interval [sec]
L _{i, max} : Upper limit [bit] of the amount of information transmitted at a time from the information source i
R _j : Physical rate of transmission channel [bit / sec]
(J: 1 to K: K is the number of terminal devices)

The base station performs communication by assigning a transmission opportunity to each transmission queue during a service interval,
It is preferable that the calculation unit calculates the bandwidth while optimizing the length of the service interval.
Since the service interval as well as the bandwidth affects the delay time, the delay time can be appropriately shortened by optimizing the service interval.

  Further, the acquisition unit can acquire the parameter and the maximum allowable transmission delay amount from the terminal device, and the bandwidth calculated by the calculation unit is assigned to the terminal device for bandwidth allocation to the transmission queue of the terminal device. It is preferable that transmission to the device is possible, and in this case, bandwidth allocation to the transmission queue of the terminal device can be performed.

  Furthermore, the base station is preferably configured to allocate the bandwidth calculated by the arithmetic unit to the transmission queue of the base station. In this case, the bandwidth can be allocated to the transmission queue of the own station.

[Terminal device]
Another aspect of the present invention is a terminal device that allocates a band to a transmission queue provided for each type of transmission information based on band allocation information received from a base station. A parameter capable of calculating the transmission delay amount and the maximum allowable transmission delay amount of the transmission information can be transmitted to the base station for band allocation calculation in the base station.

  According to this terminal device, since a parameter capable of calculating a maximum transmission delay amount of transmission information and a maximum allowable transmission delay amount of the transmission information can be transmitted to the base station when a band is given, the band allocation is performed in the base station. Arithmetic can be performed.

[Information source device]
From another viewpoint, the present invention provides an information source device that provides transmission information to a base station or a terminal device, and a parameter that can calculate a maximum transmission delay amount of the transmission information when a band is given, and a maximum of the information An allowable transmission delay amount can be transmitted to the base station or the terminal device for bandwidth allocation calculation.

  According to this information source device, when a band is given, a parameter capable of calculating the maximum transmission delay amount of the transmission information and the maximum allowable transmission delay amount of the information are sent to the base station or the terminal device for bandwidth allocation calculation. Since transmission is possible, bandwidth allocation calculation can be performed in the base station.

  Moreover, it is preferable that the information source device includes a shaper unit that absorbs traffic fluctuation of transmission information. By absorbing the traffic fluctuation in the information source device, the burstiness of the traffic given to the transmission queue of the base station or the terminal device is suppressed. In addition, the shaper part can adopt a device that absorbs traffic fluctuations by the token bucket model.

[Communication method]
From another viewpoint, the present invention is a method of performing communication by assigning a bandwidth to each transmission queue provided for each piece of transmission information, and when the bandwidth of the transmission information is given, the maximum of the transmission information is obtained. The transmission delay amount is represented by a parameter that can be calculated, and the bandwidth allocated to each transmission queue is calculated based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information, and the calculated bandwidth is transmitted to each transmission It is characterized by assigning to a queue.

  According to the present invention, when a band is given, it is possible to efficiently allocate a band by a parameter that can calculate the maximum transmission delay amount of transmission information and the maximum allowable transmission delay amount of the transmission information.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking communication using an IEEE 802.11 wireless LAN as an example.
[Overall configuration of wireless LAN (uplink)]
FIG. 1 shows an uplink wireless transmission path in a wireless LAN. In the wireless LAN of FIG. 1, a plurality of terminal devices STA-j (j: 1 to K; K is the number of terminal devices) are connected to an access point (AccessPoint) device AP serving as a base station (BS). ing.

An information source device RS for information transmitted from the terminal devices STA-1 to STA-K to the base station AP is connected to each terminal device STA-1 to STA-K.
As shown in the figure, there are various information source devices RS connected to the terminal device, such as a video phone RS that generates image information and audio information, and a personal computer RS that generates information sent to the Internet.
The information source devices RS and RS may be devices that can give the terminal devices STA-1 to STA-K information for transmission from the terminal devices STA-1 to STA-K to the base station AP. The information source device RS itself does not need to generate information.

Each of the terminal apparatuses STA-1 to STA-K has one or more types of information to be transmitted corresponding to the connected information sources, and each terminal apparatus STA-1 to STA-K wants to transmit The same number N of transmission queues Q-1 to QN as the types of information are provided. Logically, the base station AP can be regarded as performing communication independently for each of the transmission queues Q-1 to QN.
The base station AP performs communication by assigning a band (communication time), which is a wireless communication resource, to each of these transmission queues Q-1 to Q-N.

In the case of a videophone, the information source device RS has a camera 10 and a microphone 12 as information sources.
An image captured by the camera 10 is converted into digital video data (transmission information) by the video encoder 11 and output to the transmission queue Q-1 of the terminal device STA-1.
The voice collected by the microphone 12 of the videophone RS-1 is converted into digital voice data (transmission information) by the voice encoder 13 and output to the transmission queue Q-2 of the terminal device STA-1. .

When the base stations AP allocate the bands r ₁ ′ and r ₂ ′ to the transmission queues Q-1 and Q-2 of the terminal device STA-1, respectively, the band r ₁ ′ as a whole of the terminal device STA-1 + R ₂ ′ is assigned, and communication from the terminal device STA-1 to the access point AP is performed in the band r ₁ ′ + r ₂ ′.

Further, when the information source device RS is a personal computer, the information source device RS has an input device 14 such as a keyboard or a mouse as an information source, and input information from the keyboard or mouse is received by the Web browser 15. It is converted into Web data (transmission information) and output to the transmission queue Q-N of the terminal device STA-K.
When the band r _N ′ is allocated by the base station AP to the transmission queue Q-N of the terminal device STA-K, communication from the terminal device STA-K to the access point AP is performed in the band r _N ′. .

Incidentally, each of the entire band (physical _rate) R 1 to R _K between each of the terminal devices STA-1~STA-K and the base station AP, but can be the same in the wired transmission path, the present embodiment in a wireless transmission path as, depending on the environment in which the terminal apparatus STA-1~STA-K is located, the physical rate _{R 1} between one station STA-1 and the base station, there station STA −2 and the base station AP may be different from the physical rate R ₂ , in FIG. 1, the physical rate is indicated by different symbols R ₁ and R _K for the terminal apparatuses STA- ₁ to STA-K. Yes.

また、帯域ｒ_ｉ’が割り当てられても、送信情報の送信のために実際に利用される実効帯域ｒ_ｉは、オーバヘッド等のため、割当帯域ｒ_ｉ’よりも小さくなる。 However, in the following, it is assumed that the physical rates R _{1 to} R _K between the terminal apparatuses STA-1 to STA-K and the base station AP are the same value R (for example, 54 Mbps). . In this case, the band r _i ′ assigned to each transmission queue (information source i) is expressed by the following equation (1).

Even if the band r _i ′ is allocated, the effective band r _i actually used for transmitting the transmission information is smaller than the allocated band r _i ′ due to overhead and the like.

[Uplink bandwidth allocation]
Hereinafter, in the uplink of the wireless LAN of FIG. 1, the base station AP allocates the bands r ₁ ′ to r _N ′ to the transmission queues Q- ₁ to QN of the terminal apparatuses STA-1 to STA-K. Will be described.

Each information source device RS is based on a token bucket model, and the burstiness of the information source is transmitted from the information source in a short period of time to the upper limit L _max [bit] of the amount of information transmitted from the information source at a time. There is provided a parameter extraction unit 21 for representing three parameters: an upper limit σ [bit] of information to be transmitted and an upper limit ρ [bit / s] of a transmission rate over a long period of time.

[Token Bucket Model (Token Bucket)]
The token bucket model is a model as shown in FIG. Details of the token bucket model are described in Non-Patent Document 1.
In the token bucket model, information traffic can be output to the transmission queue by consuming tokens stored in the bucket TB.

  Here, the token is like a ticket for transmitting information to the transmission queue. When transmitting information of the traffic length L (bit), the same amount L (bit) accumulated in the bucket TB is used. Consume tokens. If there is no token in the bucket TB, information cannot be transmitted to the transmission queue.

  On the other hand, tokens generated at the token generation rate ρ [bit / s] are accumulated in the bucket TB, and if the tokens are not consumed while being accumulated, the tokens are full with the maximum capacity σ [bit] of the bucket. When the bucket TB is full of tokens, the token amount of the bucket TB does not increase any more even if the token is further input to the bucket TB, and the token is discarded.

For example, the variable transmission rate (VBR: Variable Bit Rate) traffic in which the average transmission rate μ [bit / s] and the total traffic transmitted up to time t shown in FIG. Consider the case given to.
Here, FIG. 4 shows a temporal change in the total amount of tokens accumulated in the bucket TB. When the token bucket is used, if the total amount of data A (t) that is actually transmitted is equal to or less than the total token amount σ + ρt, information can be transmitted reliably.
On the other hand, when the total amount of data A (t) that is actually transmitted becomes larger than the total token amount σ + ρt, the traffic is discarded.

From the above, if the token bucket is used, the burstiness of the information source can be absorbed, and the average transmission rate and burstiness of the information source can be replaced with the three parameters ρ, σ, and L _max .
That is, the traffic length (maximum packet length) L _max is the upper limit L _max [bit] of the amount of information transmitted from the information source at a time, and the maximum capacity σ of the bucket TB is transmitted from the information source in a short time. The upper limit σ [bit] of information becomes the token generation rate ρ, and the upper limit ρ [bit / s] of the transmission rate over a long period of time.

In the present embodiment, when a packet of length L consumes a token of a bucket TB, the token consumption is [L + overhead length]. That is, the upper limit (maximum packet length) L _max of the amount of information transmitted at a time from the information source is [actual maximum packet length + overhead length]. By doing so, even when overhead is added to the transmission information and transmitted, the bandwidth can be calculated appropriately.

Here, in order to transmit information correctly, it is preferable that the upper limit ρ of the transmission rate over a long period in the token bucket ρ ≧ the average transmission rate μ in the information source. This is because if ρ <μ, the traffic that cannot acquire the token is discarded before the token bucket TB.
However, even if ρ <μ, if a buffer memory is inserted before the token bucket TB, the traffic can be held for a certain amount of time without being discarded.

[Maximum transmission delay and bandwidth]
Here, the maximum transmission delay amount D _{i, max} of the information source i and the band r _i are related to each other, and the maximum transmission delay D _{i, max} increases as the band r _{i decreases} .
The relationship between the maximum transmission delay amount D _{i, max} and the band r _i can be expressed by the three parameters ρ _i , σ _i , L _{i, max of the} token bucket model corresponding to each information source i.

That is, the relationship between each parameter is illustrated in FIG. 5 using the parameters ρ _i , σ _i , L _{i, max} .
In FIG. 5, the delay time until the traffic to be transmitted first occurs at time t = 0 and the next transmission opportunity comes is denoted by Θ _i . The total transmission traffic A _i (t) up to time t is equal to or less than the total amount of tokens σ _i + ρ _i t input to the token bucket TB up to time t, and the band r _i is a value larger than ρ _i. It is said.
At this time, the maximum transmission delay amount D _{i, max} of the information source i is as shown in FIG. 5, and the following relational expression is established. The following relational expression is also described in Non-Patent Document 1.

Therefore, the maximum transmission delay amount D _{i, max} when the band r _i is given can be described as follows.

が出来るだけ小さくなるように、割当帯域ｒ_ｉ’を決定する。あるいは、一般的に実効帯域に付加帯域を加えると割当帯域となるため、まず実効帯域の総和が最小となるように実効帯域を決定してから、割当帯域を計算してもよい（［００５６］参照）。 [Optimization of band ri]
When the bands r _i ′ (r _i ′> r _i ) are allocated to the transmission queues Q-1 to QN corresponding to each information source i, here, in order to use the band efficiently, the sum of the allocated bands r _i ′ is used.

The allocated bandwidth r _i ′ is determined so as to be as small as possible. Alternatively, since an additional bandwidth is generally added to the effective bandwidth, the allocated bandwidth is obtained. Therefore, the effective bandwidth may be determined first so that the total effective bandwidth is minimized, and then the allocated bandwidth may be calculated ([0056] reference).

However, if maximum transmission delay allowed in each transmission information i (the maximum allowable transmission delay) _{DB i,} and _max, the maximum allowable transmission delay _{DB i, max} is the maximum transmission delay in the effective bandwidth _{r i D i , Max} = σ _i / r _i + Θ _i + L _{i, max} / r _i or more (constraint condition 1).
The effective band r _i should be equal to or greater than the upper limit ρ _i [bit / s] of the transmission rate over a long period based on the token bucket model (constraint condition 2).

The problem of minimizing the total sum of the allocated bands r _i ′ under the constraints 1 and 2 is to replace the following objective function with a method (linear programming or nonlinear programming) that minimizes the constraints under the constraints 1 and 2. be able to. Thus, for example, it is possible to calculate the optimized effective bandwidth r _i by sequential quadratic programming (SQP).

  The IEEE 802.11 wireless LAN is a communication method in which a common transmission channel is divided by time and shared among a plurality of terminal apparatuses, and the delay time Θ is a service interval SI [sec] as shown in FIG. Based on the transmission opportunity TXOP [sec], it can be calculated as follows. Note that the exact definition of TXOP and SI is based on the definition of IEEE 802.11 wireless LAN.

For example, each transmission opportunity (TXOP _i [sec]) for each transmission queue Q-i is started at a certain time in the service interval SI [sec], and the transmission queue Q-i does not transmit a TXOP even if there is no transmission packet. If it is not opened, it can be calculated by the following formula.

Further, TXOP _i ends when there is no transmission packet, and when the next transmission queue Q-i starts TXOP _i , it can be calculated by the following equation.

Further, when each TXOP _i starts at certain times with in SI, opens the TXOP _i it had not been transmitted packet can be calculated by the following equation.

The band r _i optimized as described above is assigned band r _i 'by adding a predetermined additional band to the effective band r _i as necessary, and the band terminals STA-1 to STA-K. Are assigned to the transmission queues Q-1 to QN, and communication is performed using the band r _i (r _i ′).

[Optimization of service interval SI]
In the optimization, not only the band r _i (r _i ′) but also the service interval SI can be optimized.

と定義し、最適化の対象パラメータｘに帯域ｒ_ｉだけでなくＳＩを加えることで、ＳＩも最適化することができる。
なお、上記式の定義では、ＴＸＯＰ_ｉは、送信情報の送信のために無駄なく利用され、しかも、ＴＸＯＰ_ｉ以外に送信情報の送信に必要とされる割当時間（例えば、オーバヘッドΔ［ｓｅｃ］）がないため、割当帯域ｒ_ｉ’＝実効帯域ｒ_ｉとなる。 That is, as is clear from the formula for calculating the delay time theta _{i, i} delay theta by reducing the SI can be reduced. However, if the SI is too small, the band r _i (r _i ′) allocated to each of the transmission queues Q-1 to QN becomes too small, and transmission may not be performed.
Therefore, the effective band r _i in the above constraint condition 1 is

SI can be optimized by adding not only the band r _i but also the SI to the optimization target parameter x.
In the definition of the above equation, TXOP _i is used without waste for transmission information transmission, and allocation time (for example, overhead Δ [sec]) required for transmission information transmission other than TXOP _i is used. Therefore, the allocated bandwidth r _i ′ = effective bandwidth r _i .

ここで、Δ_ｉは、各ＴＸＯＰ_ｉにおいて、送信情報ｉを送信するのに必要なオーバヘッド（ガード時間、プリアンブル、ＭＡＣメッセージ、その他の制御信号）であり、基地局は、Δ_ｉ＋ＴＸＯＰ_ｉの時間内において、各送信キューに対して、伝送チャンネルの排他的な使用を認める。なお、Δ_ｉは、各ＴＸＯＰ_ｉについて、異なっていてもよいし、共通であってもよい。 [Consideration of overhead]
Assignment _'when the communication scheme is defined by the following formula, allocated bandwidth r _i' band r _i described calculation to optimize the service interval SI and.

Here, Δ _i is the overhead (guard time, preamble, MAC message, and other control signals) necessary to transmit the transmission information _i in each TXOP _i , and the base station takes the time of Δ _i + TXOP _i In each of the transmission queues, exclusive use of the transmission channel is permitted. Note that Δ _i may be different or common for each TXOP _i .

If the overhead for transmission of the transmission information i is required, be calculated effective bandwidth r _i by optimizing the band to be actually allocated are those additional band of the overhead fraction was added to the effective bandwidth r _i Need to be. Therefore, calculation unit, allocated bandwidth r _{i 'and} based on the constraint condition 1 in accordance with the above definition of the effective bandwidth r _i, to calculate the effective bandwidth r _i, by adding the overhead fraction, suitable allocated bandwidth r _i The value of 'is obtained.

[Consideration when TXOP is released halfway]
_'When is defined by the following formula, allocated bandwidth r _i' allocated bandwidth r _i described calculation to optimize the service interval SI.

The TXOP _i assigned to the transmission queue Q-i in which the base station AP is located may be released halfway within the time period of the TXOP _i by the terminal device. That is, as shown in FIG. 7, even when there is a packet to be transmitted to the transmission queue Q-i, the remaining time of the TXOP _i is small and transmission of the packet in the transmission queue cannot be completed. The TXOP _i is released halfway, and the remaining time of TXOP _i is wasted. The maximum value of wasted time is L _{i, max} / R _i , and the effective band r _i is lower than the allocated band r _i ′ by this amount.

Therefore, when calculating the effective band r _i based on the constraint condition 1, the calculation unit calculates the effective band r _i according to the above definition. Then, based on the above definition, the calculation unit adds the amount of L _{i, max} to the effective band r _i and calculates the allocated band r _i ′.

In the above description, the calculation considering the overhead and the calculation when the TXOP is released halfway are described separately. However, the calculation considering both the overhead and the TXOP is released halfway is performed. Also good.
That is, when calculating the effective band r _i based on the constraint condition 1, the calculation unit can calculate the effective band r _i according to the following definition and calculate the allocated band r _i ′ based on the following definition.

[Bandwidth allocation procedure in Fig. 1 (uplink)]
The above band allocation process will be described more specifically with reference to FIG.
Here, in the information source device RS of FIG. 1, the burst property of the information source is not absorbed by the token bucket model. In the case of FIG. 1, the transmission information is video data, audio data, and Web data input from an input device, and the burst property is not so high.
However, since the parameters ρ _i , σ _i , L _{i, max} are necessary for bandwidth allocation, the parameter extraction unit 21 obtains the parameters ρ _i , σ _i , L _{i, max} from the transmission information itself. . That is, in FIG. 1, the parameter extraction unit 21 acquires parameters ρ _i , σ _i , L _{i, max} from the video encoder 11, the audio encoder 13, and the web browser 15.

In order for the parameter extraction unit 21 to acquire the parameters ρ _i , σ _i , L _{i, max} , for example, if a token bucket model is interposed between the video encoder 11 and the transmission queue Q-1. In addition, the parameters ρ _i , σ _i , L _{i, max} of the token bucket model that can give the transmission information to the transmission queue without discarding the traffic may be determined.
That is, it is only necessary to determine ρ _i and σ _{i such} that A _i (t) ≈μ _i ≦ σ _i + ρ _i t, and L _{i, max} is the upper limit of the amount of information transmitted from the information source i at a time. Therefore, it can be obtained directly from the transmission information.

Further, the parameter extraction unit 21 acquires the maximum allowable transmission delay amount DB _{i, max} of each transmission information based on the type of transmission information from the information source.

The maximum allowable transmission delay amount DB _max of transmission information differs depending on the type of information, and generally, it is required to be relatively small in the case of audio data and video data that change in real time. It may be large.

Extraction information such as ρ _i , σ _i , L _{i, max} , DB _{i, max} for each transmission information i acquired by the parameter extraction unit 21 of the information source device RS, RS is extracted from the terminal devices STA-1 to STA-K. It is sent to the information transmitters 31, 31, 31.
The terminal devices STA-1 to STA-K that have received the extraction information ρ _i , σ _i , L _{i, max} and DB _{i, max} transmit the extraction information of each transmission information to the base station AP. That is, the extracted information transmitting units 31 and 31 provide the extracted information ρ _i , σ _i , L _{i, max} , DB _{i, max} to the wireless multiplexing unit 32 for transmitting the transmission queue information, and the wireless multiplexing unit 32 Extraction information is sent to the base station AP.

In the base station AP, the extracted information receiving units 42 and 42 via the wireless distribution unit 41 allow the extracted information (three parameters ρ _i , σ _i) of each transmission information from each terminal device STA-1 to STA-K. , L _{i, max} and maximum allowable delay amount DB _{i, max} ). That is, the extracted information receiving units 42 and 42 are capable of calculating the maximum transmission delay amount of the transmission information when the band r _i is given _, and the maximum allowable transmission delay amount of the transmission information and the parameters ρ _i , σ _i , _{Li, max.} It functions as an acquisition unit that acquires DB _{i, max} .
Further, the base station AP also acquires a physical rate (full band) R _j between the terminal devices STA-1 to STA-K through communication with the terminal devices STA-1 to STA-K.

Based on the extracted information (three parameters ρ _i , σ _i , L _{i, max} , and maximum allowable delay amount DB _{i, max} ) and the physical rate, the allocated bandwidth calculation unit 43 provided in the base station AP The bandwidth r _i ′ and the service interval SI are calculated by the above-described optimization process (sequential quadratic programming or the like).

The calculated band r _i ′ and service interval SI are transmitted from the radio multiplexing unit 44 of the base station AP to each terminal apparatus STA-1 to STA-K. That is, the bands r ₁ ′, r ₂ ′ and SI are sent to the terminal apparatus STA-1, and the bands r _N ′ and SI are sent to the terminal apparatus STA-K.
The SI is reported from the base station AP to the terminal devices STA-1 to STA-K in the area as a broadcast message.

In each of the terminal apparatuses STA-1 to STA-K, the allocation information receiving units 34 and 34 receive the allocated bandwidth r _i ′ and the service interval SI via the radio distribution units 33 and 33. The received allocated band r _i ′ is allocated to a corresponding transmission queue in each terminal apparatus STA-1 to STA-K.
That is, the transmit queue Q-1 of the terminal apparatus STA-1, the bandwidth _{r 1} 'is assigned to the same transmit queue Q-2, the bandwidth _{r 2'} is allocated. Further, the band r _N ′ is allocated to the transmission queue QN of the terminal device STA-K.
Also, the terminal devices STA-1 to STA-K can detect the value of the service interval SI as a broadcast message by looking at a predetermined position of a control signal coming from the base station AP. Each terminal apparatus STA-1 to STA-K can communicate synchronously by using the detected SI.

[Downlink bandwidth allocation]
FIG. 7 shows a downlink wireless transmission path in the same wireless LAN as FIG. Note that points not particularly described regarding processing in the downlink are the same as those in the uplink.

In the downlink, the information source device RS for information to be sent from the base station AP to the terminal devices STA-1 to STA-K is an ADSL modem if the backbone network is ADSL, and an optical receiver if the backbone network is an optical line. Become.
Therefore, the transmission information here is information transmitted from a server such as the Internet.
In addition, the base station AP includes a number N of transmission queues Q-1 to Q-N corresponding to the type of transmission information. In the downlink, the base station AP transmits its own transmission queues Q-1 to Q-Q. Bandwidth r _i 'is assigned to -N.

The traffic of information transmitted from the server on the Internet greatly depends on the performance of the server at the transmission source, so the burstiness is very large, and it is directly transmitted to the transmission queues Q-1 to Q-N of the base station AP. If given, appropriate bandwidth allocation cannot be performed.
Therefore, the information source device RS (ADSL modem, optical receiver) here corresponds to each of the transmission queues Q-1 to QN with shapers 22, 22, and 22 for absorbing the burstiness of traffic. I have.

  The shaver unit 22 absorbs traffic burstiness by the token bucket model described above. That is, the transmission from the backbone network is received via the signal distribution unit 23, and after the burstiness of traffic is absorbed by the shaper unit 22 corresponding to the type of transmission information, each transmission queue Q-1 To QN.

Each shaper unit 22 has parameters ρ _i , σ _i , L _{i, max} of the token bucket model. Therefore, in the parameter extraction unit in FIG. 7, ρ _i , σ _i , L _i from the shaper unit 22. _{, Max} may be obtained. Further, the parameter extraction unit 21 acquires the maximum allowable transmission delay amount DB _{i, max} of each piece of transmission information based on the type of transmission information.

Extraction information such as ρ _i , σ _i , L _{i, max} , DB _{i, max} for each transmission information i acquired by the parameter extraction unit 21 of the information source device RS is the terminal devices STA-1 to STA-K of the base station AP. To the extracted information receiving units 42, 42, 42. That is, the extracted information receiving units 42, 42, and 42 are provided with the parameters ρ _i , σ _i , L _{i, max} and the maximum allowable transmission of the transmission information that can calculate the maximum transmission delay amount of the transmission information given the band r _i ′. It functions as an acquisition unit that acquires the delay amount DB _{i, max} .
Further, the base station AP also acquires a physical rate (full band) R _j between the terminal devices STA-1 to STA-K through communication with the terminal devices STA-1 to STA-K.

The allocated band calculation unit 43 provided in the base station AP extracts extracted information (three parameters ρ _i , σ _i , L _{i, max} , and maximum allowable delay amount DB _{i, max} ) and physical rate R _j. Based on the above, the bandwidth r _i ′ and the service interval SI are calculated by the above-described optimization process (sequential quadratic programming or the like).

Then, the calculated allocated bandwidth r _i ′ is allocated to the transmission queue of the local station AP.
That is, the band r ₁ ′ is allocated to the transmission queue Q-1 of the base station AP, the band r ₂ ′ is allocated to the transmission queue Q-2, and the band r _N ′ is allocated to the transmission queue Q-N. Assigned.

  The present invention is not limited to the above embodiment. For example, the present invention is not limited to a wireless LAN, and can be applied to other communication systems.

  Further, the shaper unit included in the information source device RS of FIG. 7 may be included in the information source device RS of FIG. Furthermore, the shaper unit and / or the parameter extraction unit may be provided before the transmission queue of the terminal device or the base station device to which the information source device RS is connected instead of the information source device RS.

Further, when performing an operation for minimizing the total sum of the bands r _i, the total sum of the bands r _i ′ may be a simple sum of all the allocated bands r ₁ ′ to r _N ′, or the total allocated band r ₁ The sum of the squares of “˜r _N ” may be used as the sum of the bands r _i ′.

1 is an overall configuration block diagram of a wireless LAN (uplink). FIG. It is a schematic diagram of a token bucket model. It is a figure which shows the example of a transmission rate variable traffic. It is a graph which shows the accumulation | storage token total amount to a token bucket. It is a graph which shows the relationship between the maximum delay of an information source, and a zone | band. It is explanatory drawing of service interval SI and transmission opportunity TXOP. It is explanatory drawing that TXOP is released on the way. 1 is an overall configuration block diagram of a wireless LAN (downlink). FIG.

Explanation of symbols

AP base station STA-1 terminal device STA-K terminal device RS information source device Q-1 transmission queue Q-2 transmission queue QK transmission queue ρ _i parameter σ _i parameter L _{i, max} parameter D _{i, max} Maximum transmission delay amount DB _{i, max} Maximum allowable transmission delay amount of transmission information 21 Parameter extraction unit 22 Shaper unit 42 Extraction information reception unit (acquisition unit)
43 Allocated bandwidth calculation unit (calculation unit)

Claims (26)

A base station capable of communicating with a terminal device,
A calculation unit for calculating a bandwidth allocated to a transmission queue provided for each type of transmission information in a base station and / or a terminal device;
A parameter capable of calculating the maximum transmission delay amount of transmission information when a band is given, and an acquisition unit for acquiring the maximum allowable transmission delay amount of the transmission information,
The calculation unit calculates a bandwidth to be allocated to each transmission queue so that a maximum transmission delay amount calculated from the parameter of each transmission information is equal to or less than a maximum allowable transmission delay amount of each transmission information. base station.   2. The base station according to claim 1, wherein the parameter represents the traffic of transmission information based on a model that absorbs traffic fluctuation. The model is a token bucket model,
The parameters include an upper limit on the amount of information transmitted from the information source at a time, an upper limit on the amount of information transmitted from the information source in a short time, and an upper limit on the transmission rate over a long period of information transmitted from the information source. The base station according to claim 2, wherein: A base station capable of communicating with a terminal device,
A calculation unit for calculating a bandwidth allocated to a transmission queue provided for each type of transmission information in a base station and / or a terminal device;
A parameter capable of calculating the maximum transmission delay amount of transmission information when a band is given, and an acquisition unit for acquiring the maximum allowable transmission delay amount of the transmission information,
The calculation unit calculates a bandwidth to be assigned to each transmission queue based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information,
The arithmetic unit, while the maximum transmission delay amount of the transmission information in a certain band becomes equal to or less than the maximum allowable transmission delay amount of the transmission information, based Chikyoku you and calculates the smallest possible bandwidth. A base station capable of communicating with a terminal device,
A calculation unit for calculating a bandwidth allocated to a transmission queue provided for each type of transmission information in a base station and / or a terminal device;
A parameter capable of calculating the maximum transmission delay amount of transmission information when a band is given, and an acquisition unit for acquiring the maximum allowable transmission delay amount of the transmission information,
The calculation unit calculates a bandwidth to be assigned to each transmission queue based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information,
The arithmetic unit, the sum of the bandwidth of each transmission queue, under the constraints of the following, groups Chikyoku you and calculates the band so as to minimize.
Condition 1: DB _{i, max} ≧ σ _i / r _i + Θ _i −L _{i, max} / r _i
Condition 2: r _i ≧ ρ _i
However,
i: Information source (1 to n: n is the number of information sources)
DB _{i, max} : Maximum allowable transmission delay amount of transmission information from information source i σ _i : Upper limit of information amount transmitted from information source i in a short period r _i : Bandwidth of transmission queue corresponding to information source i Θ _i : Delay time from the occurrence of traffic in the information source i to actual transmission L _{i, max} : Upper limit of the amount of information transmitted from the information source i at a time ρ _i : Over a long period of information transmitted from the information source i Maximum transmission rate A base station capable of communicating with a terminal device,
A calculation unit for calculating a bandwidth allocated to a transmission queue provided for each type of transmission information in a base station and / or a terminal device;
A parameter capable of calculating the maximum transmission delay amount of transmission information when a band is given, and an acquisition unit for acquiring the maximum allowable transmission delay amount of the transmission information,
The calculation unit calculates a bandwidth to be assigned to each transmission queue based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information,
The calculation unit calculates an effective bandwidth that can be actually used for transmission of each transmission information based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information, and sets a bandwidth larger than the effective bandwidth to a transmission queue. group Chikyoku you and calculates as allocated bandwidth to.   7. The base station according to claim 6, wherein the arithmetic unit adds the bandwidth for transmitting at least the overhead necessary for transmitting the transmission information to the calculated effective bandwidth to obtain an allocated bandwidth. A base station capable of communicating with a terminal device,
A calculation unit for calculating a bandwidth allocated to a transmission queue provided for each type of transmission information in a base station and / or a terminal device;
A parameter capable of calculating the maximum transmission delay amount of transmission information when a band is given, and an acquisition unit for acquiring the maximum allowable transmission delay amount of the transmission information,
The calculation unit calculates a bandwidth to be assigned to each transmission queue based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information,
It said base station, based on allocated bandwidth ri to the transmit queue corresponding to source i 'is you characterized in that performs communication by a communication scheme defined by the following equation Chikyoku.
r _i ′ = ((TXOP _i + Δ _i ) / SI) × R _j
However,
TXOP _i : Transmission opportunity of information source i [sec]
Δ _i : Overhead [sec] necessary for transmitting information of information source i
SI: Service interval [sec]
R _j : Physical rate of transmission channel [bit / sec]
(J: 1 to K: K is the number of terminal devices)   7. The calculation unit according to claim 6, wherein the calculation unit adds at least a band for transmitting an upper limit amount of information transmitted at a time from an information source to the calculated effective band to obtain an allocated band. base station. A base station capable of communicating with a terminal device,
A calculation unit for calculating a bandwidth allocated to a transmission queue provided for each type of transmission information in a base station and / or a terminal device;
A parameter capable of calculating the maximum transmission delay amount of transmission information when a band is given, and an acquisition unit for acquiring the maximum allowable transmission delay amount of the transmission information,
The calculation unit calculates a bandwidth to be assigned to each transmission queue based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information,
It said base station, based on the allocated bandwidth ri transmit queue 'is you characterized in that performs communication by a communication scheme defined by the following formula corresponding to source i Chikyoku.
r _i ′ = ((TXOP _i + (L _{i, max} / R _j )) / SI) × R _j
However,
TXOP _i : Transmission opportunity of information source i [sec]
SI: Service interval [sec]
L _{i, max} : Upper limit [bit] of the amount of information transmitted at a time from the information source i
R _j : Physical rate of transmission channel [bit / sec]
(J: 1 to K: K is the number of terminal devices) A base station capable of communicating with a terminal device,
A calculation unit for calculating a bandwidth allocated to a transmission queue provided for each type of transmission information in a base station and / or a terminal device;
A parameter capable of calculating the maximum transmission delay amount of transmission information when a band is given, and an acquisition unit for acquiring the maximum allowable transmission delay amount of the transmission information,
The calculation unit calculates a bandwidth to be assigned to each transmission queue based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information,
The base station performs communication by assigning a transmission opportunity to each transmission queue during a service interval,
The arithmetic unit group Chikyoku you and calculates the band while optimizing the length of the service interval. A base station capable of communicating with a terminal device,
A calculation unit for calculating a bandwidth allocated to a transmission queue provided for each type of transmission information in a base station and / or a terminal device;
A parameter capable of calculating the maximum transmission delay amount of transmission information when a band is given, and an acquisition unit for acquiring the maximum allowable transmission delay amount of the transmission information,
The calculation unit calculates a bandwidth to be assigned to each transmission queue based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information,
The acquisition unit can acquire the parameter and the maximum allowable transmission delay amount from the terminal device,
The bandwidth calculated by the calculating unit, the group Chikyoku characterized in that it is transmitted to the terminal apparatus for bandwidth allocation to the transmission queue of the terminal device. A base station capable of communicating with a terminal device,
A calculation unit for calculating a bandwidth allocated to a transmission queue provided for each type of transmission information in a base station and / or a terminal device;
A parameter capable of calculating the maximum transmission delay amount of transmission information when a band is given, and an acquisition unit for acquiring the maximum allowable transmission delay amount of the transmission information,
The calculation unit calculates a bandwidth to be assigned to each transmission queue based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information,
The bandwidth calculated by the calculating unit, based Chikyoku you, characterized in that it is configured to allocate to the transmission queue of the base station. Based on the bandwidth allocation information received from the base station, a terminal device that allocates a bandwidth to a transmission queue provided for each type of transmission information,
A parameter capable of calculating the maximum transmission delay amount of transmission information and the maximum allowable transmission delay amount of the transmission information can be transmitted to the base station for bandwidth allocation calculation in the base station ,
A terminal apparatus that receives, from the base station, the band allocation information indicating a band to be allocated to each transmission queue calculated based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information by the base station . An information source device that provides transmission information to a base station or a terminal device,
A parameter capable of calculating the maximum transmission delay amount of the transmission information and the maximum allowable transmission delay amount of the information can be transmitted to the base station or the terminal device for bandwidth allocation calculation,
The parameters include an upper limit on the amount of information transmitted from the information source at a time, an upper limit on the amount of information transmitted from the information source in a short time, and an upper limit on the transmission rate over a long period of information transmitted from the information source. information source device are.   16. The information source device according to claim 15, further comprising a shaper unit that absorbs traffic fluctuation of transmission information. A method of performing communication by assigning a bandwidth to each transmission queue provided for each transmission information,
The traffic of the transmission information is represented by a parameter capable of calculating the maximum transmission delay amount of the transmission information when a bandwidth is given,
Calculate the bandwidth allocated to each transmission queue so that the maximum transmission delay amount calculated from the parameter of each transmission information is less than or equal to the maximum allowable transmission delay amount of each transmission information,
Assign the calculated bandwidth to each transmission queue,
A communication method characterized by the above. A base station that allocates a bandwidth to each transmission queue provided for each transmission information,
Given the bandwidth, the bandwidth allocated to each transmission queue is set so that the maximum transmission delay amount calculated from the parameter that can calculate the maximum transmission delay amount of each transmission information is less than or equal to the maximum allowable transmission delay amount of each transmission information. Calculate and assign the calculated bandwidth to each transmission queue,
A base station characterized by that. A base station that allocates a bandwidth to each transmission queue provided for each transmission information,
Given the bandwidth, the maximum transmission delay amount calculated from the parameter that can calculate the maximum transmission delay amount of each transmission information is less than the maximum allowable transmission delay amount of each transmission information, and the smallest possible bandwidth is assigned to each transmission queue. Calculate as bandwidth to be allocated
A base station characterized by that. A base station that allocates a bandwidth to each transmission queue provided for each transmission information,
Given the bandwidth, the effective bandwidth that can be actually used for transmission of each transmission information is calculated based on the parameter that can calculate the maximum transmission delay amount of each transmission information and the maximum transmission delay amount of each transmission information. A base station that calculates a larger bandwidth as a bandwidth allocated to a transmission queue. A base station that allocates a bandwidth to each transmission queue provided for each piece of transmission information in a terminal device,
When a bandwidth is given, a parameter capable of calculating the maximum transmission delay amount of each transmission information and the maximum transmission delay amount of each transmission information can be acquired from the terminal device,
A bandwidth allocated to each transmission queue is calculated based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information, and the calculated bandwidth is assigned to the terminal device for bandwidth allocation to the transmission queue of the terminal device. A base station characterized in that it can be transmitted to. A base station that allocates a bandwidth to each transmission queue provided for each piece of transmission information in the base station,
A configuration in which a bandwidth assigned to each transmission queue is calculated based on a parameter capable of calculating the maximum transmission delay amount of each transmission information and a maximum transmission delay amount of each transmission information when a bandwidth is given, and is assigned to the transmission queue of the base station A base station characterized by being. A method of performing communication by assigning a bandwidth to each transmission queue provided for each transmission information,
Given the bandwidth, the maximum transmission delay amount calculated from the parameter that can calculate the maximum transmission delay amount of each transmission information is less than the maximum allowable transmission delay amount of each transmission information, and the smallest possible bandwidth is assigned to each transmission queue. Calculate as bandwidth to be allocated
A communication method characterized by the above. A method of performing communication by assigning a bandwidth to each transmission queue provided for each transmission information,
Given the bandwidth, the effective bandwidth that can be actually used for transmission of each transmission information is calculated based on the parameter that can calculate the maximum transmission delay amount of each transmission information and the maximum transmission delay amount of each transmission information. A communication method characterized by calculating a larger bandwidth as a bandwidth allocated to a transmission queue. A method for performing communication by allocating a bandwidth to each transmission queue provided for each piece of transmission information in a terminal device,
When a bandwidth is given, a parameter capable of calculating the maximum transmission delay amount of each transmission information and the maximum transmission delay amount of each transmission information are acquired from the terminal device,
A bandwidth allocated to each transmission queue is calculated based on the parameter of each transmission information and the maximum allowable transmission delay amount of each transmission information, and the calculated bandwidth is assigned to the terminal device for bandwidth allocation to the transmission queue of the terminal device. The communication method characterized by transmitting to. A method of performing communication by allocating a bandwidth to each transmission queue provided for each piece of transmission information in a base station,
Given the bandwidth, calculate the bandwidth to be assigned to each transmission queue based on the parameter that can calculate the maximum transmission delay amount of each transmission information and the maximum transmission delay amount of each transmission information, and assign the bandwidth to the transmission queue of the base station. A characteristic communication method.

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