JP2021192475A - Wireless communication system, communication method, and wireless base station - Google Patents

Abstract

To provide a wireless communication system, a communication method, and a wireless base station that can allocate wireless resources while ensuring efficiency and fairness among users by considering the communication quality or the like of each wireless terminal in real time.SOLUTION: In a wireless communication system according to the present invention, a wireless base station receives the queue length and priority information in a buffer from each wireless terminal, and determines the amount of wireless resources that can be allocated to each wireless terminal by feedback control that simultaneously considers the received queue length and priority information and the amount of wireless resources allocated in the past and the amount of wireless resources that can be allocated.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to radio resource allocation for radio communication systems.

In the wireless communication system, allocation control of wireless resources is performed for each wireless terminal in order to avoid data collision in communication between one wireless base station and a plurality of wireless terminals. For example, in LTE (Long Term Evolution), which is a mobile wireless communication standard, and IEEE 802.11ax, which is a wireless LAN (Local Area Network), OFDMA (Orthogonal Frequency Division Multiple Access) is adopted. Or, it is assigned to each wireless terminal in units of RU (Location Unit). The relationship between the RB / RU and the data rate depends on the MCS (Modulation and Coding Scene) and the number of tones (number of subcarriers).

For RB allocation in LTE, a wireless resource allocation technology proportional to the amount of data addressed to each user and a wireless resource allocation technology considering communication quality and fairness among users have been proposed in consideration of the buffer state of each user. (See, for example, Non-Patent Documents 1 to 4).

F. Capozzi, “Downlink Packet Scheduling in LTE Cellular Networks: Key Design Issues and a Survey,” IEEE Communications, Tutorials. 15, no. 2, pp. 678-700, Second Quarter 2013. E. Khorov et al. , "A Tutorial on IEEE 802.11ax High Efficiency WLANs," IEEE Communications Services & Tutorials, vol. 21, no. 1, pp. 197-216, First Quarter 2019. G. Piro et al. , "Two-Level Downlink Scheduling for Real-Time Multimedia Services in LTE Networks," IEEE Transitions on Multimedia, vol. 13, no. 5, pp. 1052-1065, Oct. 2011. Yamashita et al., “Wireless QoS Control Technology,” NTT Technology Journal, Vol. 16, No. 7, pp. 23-28, July 2004.

However, in the OFDMA of the IEEE 802.11ax standard, when the number of wireless terminals increases due to the spread of IoT (Internet of Things) and access concentration in the event of a disaster, various quality requirements and quality fluctuations cause real-time and efficient wireless resources. There was a problem that allocation became difficult.

Therefore, in order to solve the above problems, the present invention provides a wireless communication system and a communication method capable of allocating wireless resources while ensuring efficiency and fairness among users in real time in consideration of communication quality of each wireless terminal. And to provide radio base stations.

In order to achieve the above object, in the wireless communication system according to the present invention, it is decided to determine the wireless resource allocation amount between the wireless base station and each wireless terminal by feedback control in consideration of the communication quality and the buffer state.

Specifically, the wireless communication system according to the present invention is a wireless communication system in which the wireless connection between one wireless base station and a plurality of wireless terminals is an orthogonal frequency division multiple access (OFDMA). And,
The radio base station is
An information acquisition unit that acquires information on the queue length and priority in the current buffer,
A calculation unit that calculates the radio resource allocation between the wireless terminal and the wireless terminal based on OFDMA at regular time intervals using the queue length and priority information.
A feedback unit that feeds back the calculation result of the radio resource allocation to the next calculation of the radio resource allocation performed by the calculation unit.
It is characterized by having.

This wireless communication system achieves both real-time performance and fairness by feeding back the past allocation amount of wireless resources when calculating the wireless resource allocation from the queue length and priority in the current buffer.
More specifically, the present wireless communication system is a wireless communication system that allocates wireless resources based on OFDMA to a plurality of wireless terminals at regular time intervals, and the wireless base station is in a buffer from each wireless terminal. The radio that receives the queue length and priority information and allocates it to each radio terminal by feedback control that simultaneously considers the received queue length and priority information and the amount of radio resources allocated in the past and the amount of radio resources that can be allocated. Determine the amount of resources.

At this time, the information acquired by the information acquisition unit of the wireless communication system according to the present invention is information in the buffer of the wireless base station, and the wireless resource allocation is performed from the wireless base station to the wireless terminal. It can be assigned in the downward direction.
Further, the information acquired by the information acquisition unit of the wireless communication system according to the present invention is information in the buffer of the wireless terminal, and the wireless resource allocation is in the upward direction from the wireless terminal to the wireless base station. It can also be an allocation of.
That is, the above-mentioned radio resource allocation can be applied to both the downlink direction and the uplink direction.

Further, the communication method according to the present invention is a communication method in a wireless communication system in which the wireless connection between one wireless base station and a plurality of wireless terminals is an orthogonal frequency division multiple access (OFDMA). There,
Obtaining information on the queue length and priority in the current buffer of at least one of the radio base station and the radio terminal.
Using the queue length and priority information, the calculation of the radio resource allocation with the radio terminal based on OFDMA is performed at regular time intervals, and the calculation result of the radio resource allocation is used as the next radio resource allocation. To feed back to the calculation of
It is characterized by.

Further, the radio base station according to the present invention is a radio base station in which the radio connection between a plurality of radio terminals is an orthogonal frequency division multiple access (OFDMA).
An information acquisition unit that acquires information on the queue length and priority in the current buffer of at least one of itself and the wireless terminal.
A calculation unit that calculates the radio resource allocation between the wireless terminal and the wireless terminal based on OFDMA at regular time intervals using the queue length and priority information.
A feedback unit that feeds back the calculation result of the radio resource allocation to the next calculation of the radio resource allocation performed by the calculation unit.
It is characterized by having.

The above inventions can be combined as much as possible.

The present invention can provide a wireless communication system, a communication method, and a wireless base station capable of allocating wireless resources while ensuring efficiency and fairness among users in real time in consideration of the communication quality of each wireless terminal. ..

It is a figure explaining the basic structure of the wireless communication system which concerns on this invention. It is a figure explaining the RU arrangement (20MHz channel) in the IEEE 802.11ax standard. It is a figure explaining the basic structure of the wireless communication system which concerns on this invention. It is a figure explaining the basic structure of the wireless communication system which concerns on this invention. It is a figure explaining the wireless communication system which concerns on this invention. It is a figure explaining the communication method which concerns on this invention.

An embodiment of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In addition, the components having the same reference numerals in the present specification and the drawings shall indicate the same components.

(Outline of the invention)
Non-Patent Document 3 discloses radio resource allocation based on feedback control theory and scheduling based on PF (Proportional Fair) as real-time and efficient radio resource allocation technology for LTE. However, it does not correspond to the RU allocation of the wireless LAN of IEEE 802.11ax. In addition, since wireless resource allocation and scheduling are provided as separate functions, bidirectional information exchange between the functions is impossible, and it is difficult to link real-time wireless resource allocation and schedule. Therefore, in the technology disclosed in Non-Patent Document 3, it is difficult to guarantee efficiency and fairness among users at the same time.

The present invention is based on a wireless communication system in which a wireless base station allocates wireless resources to a plurality of wireless terminals based on OFDMA at regular time intervals. The wireless communication system of the present invention simultaneously considers the queue length and priority information in the current buffer, the amount of radio resources that can be allocated, and the amount of wireless resources allocated in the past, and feedback-controls the amount of wireless resources allocated to each wireless terminal. Determined by. Since the wireless communication system of the present invention considers current information and past information, it is possible to simultaneously guarantee efficiency and fairness among users in real time.

It can be applied to both the downlink radio resource allocation from the radio base station to the radio terminal and the uplink radio resource allocation from the radio terminal to the radio base station.
In the case of downlink radio resource allocation, the radio base station determines the amount of radio resources to be allocated to each radio terminal based on the downlink queue length and priority information in its own buffer.
In the case of uplink wireless resource allocation, the wireless terminal causes the wireless base station to report the uplink queue length and priority information in the buffer in the wireless terminal, and the wireless base station allocates to each wireless terminal based on the reported information. The amount of wireless resources is determined, and information on the available frequency and amount of wireless resources is notified to each wireless terminal.

(Embodiment)
FIG. 1 is a diagram illustrating a basic structure of the wireless communication system 301 of the present embodiment. The wireless communication system 301 includes one wireless base station 10 and a plurality of wireless terminals 20. In the wireless communication system 301, the wireless connection between the wireless base station 10 and the wireless terminal 20 is an orthogonal frequency division multiple access (OFDMA: Orthogonal Frequency Division Access).

FIG. 2 is a diagram illustrating the RU arrangement of OFDMA of the IEEE 802.11ax standard. The minimum RU size R _RU1 in the IEEE 802.11ax standard is 26 tones, for example, a maximum of 9 RUs can be assigned on a 20 MHz channel. It is possible to allocate one RU per user, and as the amount of radio resources that can be allocated, the RU size is from 26 tones (RU1), 52 tones (RU2), 106 tones (RU4), and 242 tones (RU9). It shall be possible to select. The data rate of each radio terminal is determined by the number of tones of the assigned RU and the MCS. The radio resource allocation function of the present embodiment is provided in the radio base station 10.

FIG. 3 is a diagram illustrating the function of the wireless terminal 20. The wireless terminal 20 includes a wireless receiver 21, a buffer 22, and a wireless transmitter 23.
The radio receiver 21 receives the radio resource allocation information including the RU size allocated from the radio base station 10.
The buffer 22 stores the input uplink data and outputs the data based on the radio resource allocation information received from the radio base station 10. The wireless terminal 20 may include a plurality of buffers for each priority. The wireless terminal 20 acquires queue length information q [k] and priority information QoS [k] for each buffer or flow (k represents time).
The radio transmitter 23 transmits the queue length information q [k] and the priority information QoS [k] output from the buffer 22 to the radio base station 10. When a plurality of buffers exist, the wireless transmitter 23 may transmit the queue length information q [k] and the priority information QoS [k] for each buffer or each flow.

FIG. 4 is a diagram illustrating the basic functions of the radio base station 10. The radio base station 10 includes a radio receiver 11, a resource allocation computer 12, and a radio transmitter 13.
The wireless receiving means 11 receives the queue length information q [k] and the priority information QoS [k] from each wireless terminal 20.
The resource allocation computer 12 has each queue length based on the queue length information q [k] obtained from the buffer (not shown) of the radio base station 10 or the queue length information q [k] obtained from each radio terminal 20. The RU size proportional to is calculated and assigned to the downlink communication or the uplink communication with each wireless terminal 20. As the scheduling method, for example, a PF (Proportional Fair) method is adopted.
Further, the resource allocation calculator 12 transmits data or transmission data based on the priority information QoS [k] obtained from the buffer (not shown) of the radio base station 10 or the priority information QoS [k] obtained from each wireless terminal 20. Received data can be distributed to multiple buffers, and different scheduling methods can be applied to each buffer.
The radio transmitter 13 transmits the radio resource allocation information including the RU size allocated to each radio terminal 20.

FIG. 5 is a diagram illustrating an additional function of the radio base station 10. In this embodiment, uplink communication will be described for the sake of simplicity. The radio base station 10 has an information acquisition unit for acquiring information on the queue length and priority in the current buffer, and an information acquisition unit.
A calculation unit that calculates the radio resource allocation between the wireless terminal and the wireless terminal based on OFDMA at regular time intervals using the queue length and priority information.
A feedback unit that feeds back the calculation result of the radio resource allocation to the next calculation of the radio resource allocation performed by the calculation unit.
To prepare for.

Specifically, the radio base station 10 further includes a quality coefficient computer 14, a fairness coefficient computer 15, and a weighting coefficient computer 16. The information acquisition unit is a functional unit (not shown) that acquires queue length information q [k] and priority information QoS [k] from a buffer (not shown) of the radio receiver 11 or the radio base station 10. The calculation unit is a quality coefficient computer 14, a weight coefficient computer 16, and a resource allocation computer 12. The feedback unit is a fairness coefficient computer 15.

FIG. 6 is a diagram illustrating a radio resource allocation method performed by the radio base station 10. This radio resource allocation method is
Acquiring information on the queue length and priority in the current buffer of at least one of the radio base station 10 and the radio terminal 20 (step S01).
Using the queue length and priority information, the calculation of the radio resource allocation with the radio terminal 20 based on OFDMA is performed at regular time intervals (step S02).
The calculation result of the radio resource allocation is fed back to the calculation of the next radio resource allocation (step S03), and the radio resource is allocated between the radio base station 10 and the radio terminal 20 based on the calculation result (step S04). ).

[Step S01]
The wireless receiver 11 receives the queue length information q [k] and the priority information QoS [k] from each wireless terminal 20.

[Step S02]
The quality coefficient calculator 14 creates an N-dimensional priority vector {QoS [k]} having _{priority information QoS i} [k] (1 ≦ i ≦ N) obtained from each wireless terminal 20 as an element, and quality. calculating the coefficient _{K Pi (1 ≦ i ≦ N} ) of N-dimensional quality coefficient vector whose elements _{K P [k]}. However, N is the total number of wireless terminals for which priority can be set, the total number of buffers of each wireless terminal, or the total number of flows of each wireless terminal. Also, {} represents a vector.

The priority can be set for each wireless terminal, each buffer of each wireless terminal, or each flow of each wireless terminal. When set for each wireless terminal, the number of elements N of the priority vector is equal to the number of wireless terminals, and when set for each buffer of each wireless terminal, the number of elements N of the priority vector is the number of buffers of each wireless terminal. When set for each flow of each wireless terminal, the number of elements N of the priority vector is equal to the total number of flows of each wireless terminal.

ただし、太字はベクトルを表わし、Ｘ［ｋ］は各変数の時刻ｋにおけるＸの値を示す。また、係数ａ_０、ａ_１、ａ_２は、１からｐまでのＱｏＳ_ｉの範囲で品質係数Ｋ_Ｐｉが単調減少となるように設定する。 Quality factor calculator 14, in the calculation of the quality factor vector {K P _[k]}, a higher priority wireless terminal is calculated as the quality factor of the buffer to flow increases.
For example, a priority 1 and p stage p, the priority in ascending order 1 is the highest priority is assumed to be low, the quality coefficient vector at time _k {K P _[k]} is the priority at the time k vector It can be calculated by the following formula using {QoS [k]}.

However, bold letters represent vectors, and X [k] indicates the value of X at time k of each variable. The coefficient _{a 0,} a 1, _{a 2,} the quality factor _{K Pi} in a range of QoS _i from 1 to p is set to be monotonically decreased.

The number 1 is an example, and the quality coefficient computer 14 may set the quality coefficient _KPi as an arbitrary equal or non-equidistant value for each priority without depending on the above equation. Moreover, the quality coefficient calculator 14 may use a polynomial function and an exponential function of the priority vectors having 1 except the quality factor vector _{{K P [k]} {} QoS [k]}.

[Step S03]
The fairness coefficient computer 15 is based on the N-dimensional allocation RU size vector {r ₃ [k]} _{having the allocation RU size r 3i} (1 ≦ i ≦ N) output from the resource allocation computer 12 as an element. _{b i (1 ≦ i ≦ N} ) and an element N-dimensional fairness coefficient vector {b [k]} is calculated. The assigned RU size is, for example, "1" when the RU size is 26 tones, "2" when the RU size is 52 tones, "4" when the RU size is 106 tones, and "9" when the RU size is 242 tones.

ただし、Ｘ［ｋ］は時刻ｋにおける変数Ｘの値を示す。 The fairness coefficient computer 15 calculates so that the fairness coefficient of the radio terminal, the buffer, or the flow to which the radio resource is not allocated at the previous supplementing time becomes large. For example, if the penalty factor "penalty", the time k + 1 fairness coefficient at _b i [k + 1], using the fairness coefficient _b i [k] and assigned RU size _r 3i at time k [k] at time k It can be calculated by the following formula.

However, X [k] indicates the value of the variable X at time k.

In the number 2, the judgment is made based on whether or not the wireless resource is allocated to the wireless terminal, buffer or flow, but a threshold value is set and the judgment is made based on whether or not the allocation above the threshold value has been made in the past. Is also good. Further, only the value before one sampling may be used, or the values before a plurality of samplings may be used in any combination. The magnitude of the penalty coefficient is determined by the number of wireless terminals, the number of buffers, or the number of flows. For example, in the case of 10 wireless terminals, it can be set to 0.1 by "1 / number of connected devices".

[Step S02]
The weighting coefficient calculator 16 creates an N-dimensional queue length vector {q [k]} having _{the queue length information q i} [k] (1 ≦ i ≦ N) obtained from each wireless terminal 20 as an element. When an output quality coefficient vector by the quality coefficient calculator _{14 {K P [k]}} , a fairness factor fairness coefficient vector outputted by computer 15 {b [k]}, weighting coefficients from w _{i [k} ] (1 ≦ i ≦ N) as an element, the N-dimensional weighting coefficient vector {w [k]} is calculated.

ただし、［ｋ］は各変数の時刻ｋにおける値を示す。また、演算子“〇”はアダマール積を表していて、要素毎の積を計算する。 The weighting factor can be calculated in combination with the quality factor and the fairness factor so as to be proportional to the queue length. For example, in the case of proportional to the queue length, the weighting coefficient vector at time k {w [k]} is the queue length vector at time k {q [k]} and the quality coefficient vector at time k _{K P [k]} and It can be calculated by the following formula using the fairness coefficient vector {b [k]} at time k.

However, [k] indicates the value of each variable at time k. In addition, the operator "○" represents the Hadamard product, and the product for each element is calculated.

In addition to the calculation of Equation 3, the weighting coefficient may be calculated by combining the rate of change in the cue length and the integrated value of the cue length. In this case, the terms of the differential value or the integral value of {q [k]} can be linearly combined.

[Step S02]
The additional function of the resource allocation computer 12 will be described. _{The resource allocation computer 12 calculates the allocation RU size vector {r 3} [k]} from the weight coefficient vector {w [k]} output from the weight coefficient computer 16. An example of calculating the assigned RU size vector {r ₃ [k]} will be described below.

First, among the N elements of the weighting coefficient vector {w [k]}, only M elements, which is the maximum number of RUs that can be used, are selected in descending order of value. For example, M = 9 for FIG. 2 (A), M = 5 for FIG. 2 (B), M = 3 for FIG. 2 (C), and M = 1 for FIG. 2 (D). Become. If multiple elements have the same value, select them randomly. The selected M elements substitute the same value for the same element of the newly defined N-dimensional weighting coefficient vector {w'[k]}. 0 is assigned to the element that is not selected.

ただし、［ｋ］は各変数の時刻ｋにおける値を示す。また、Ｒ_Ｔは利用可能なデータレートである。例えば、２０ＭＨｚチャネルで１６−ＱＡＭ、符号化率３／４の場合はＲ_Ｔを４８．８Ｍｂｐｓとする。 Allocate radio resources to each radio terminal, buffer or flow in proportion to the weighting factor. _{For example, the provisional allocation rate vector {r 1} [k]} at the N-dimensional time k having the provisional allocation rate r _1i [k] (1 ≦ i ≦ N) as an element is calculated by the following formula.

However, [k] indicates the value of each variable at time k. Also, _RT is an available data rate. For example, if at 20MHz channel 16-QAM, the coding rate 3/4 to 48.8Mbps the _{R T.}

また、［ｋ］は各変数の時刻ｋにおける値を示す。Ｒ_ＲＵ１は２６トーンの場合のデータレートを表している。端数処理には、四捨五入以外に切り上げや切り捨てを用いても良い。 Next, from the provisional allocation rate vector {r ₁ [k]}, _{the provisional allocation RU size vector {r 2} [k]} at _{the N-dimensional time k having the provisional allocation RU size r 2i} (1 ≦ i ≦ N) as an element. Is calculated. Since the provisional allocation RU size r _2i takes only an integer value, rounding to the nearest whole number is performed. For example, when rounding is used for rounding, the provisional allocation RU size vector {r ₂ [k]} can be calculated as follows.

Further, [k] indicates the value of each variable at time k. _RRU1 represents the data rate for 26 tones. In addition to rounding, rounding up or rounding down may be used for rounding.

The value that the assigned RU size r _3i [k] can take is limited to a predetermined integer value. For example, in the case of a 20 MHz channel, the RU size is one of 1, 2, 4, 9 (26 tones (RU1), 52 tones (RU2), 106 tones (RU4), 242 tones (RU9)) as shown in FIG. Therefore, the value that can be taken by each element of the assigned RU size vector {r ₃ [k]} is also 1, 2, 4, or 9.

Finally, the assigned RU size vector {r ₃ [k]} is generated as follows.
Temporary allocation The values are assigned to the same elements of the _{RU size vector {r 3} [k]} in order from the element with the largest value of the RU size vector {r _{2 [k]}.} If multiple elements have the same value, select them randomly. The value of each element assigned to {r ₃ [k]} is integrated, and the value assignment is repeated within the range where the integrated value does not exceed the maximum number M of available RUs. When the integrated value exceeds M, the substitution is stopped, and 0 is substituted for the remaining elements.

[Step S04]
The radio transmitter 13 receives the allocation RU size vector {r ₃ [k]} calculated by the resource allocation computer 12, and transmits the radio resource allocation information including the RU size allocated to each radio terminal, buffer or flow to the radio terminal. Send to 20.

(Other embodiments)
In the above embodiment, the wireless resource allocation method for uplink communication has been described, but it is clear that the method can also be applied to downlink communication.
In the above embodiment, the wireless communication system based on the IEEE 802.11ax standard has been described, but it is clear that it can be applied to any communication system that adopts OFDMA.
Further, the radio base station 10 can be realized by a computer and a program, and the program can be recorded on a recording medium or provided through a network.

10: Wireless base station 11: Wireless receiver 12: Resource allocation calculator 13: Wireless transmitter 14: Quality coefficient calculator 15: Fairness coefficient calculator 16: Weight coefficient calculator 20: Wireless terminal 21: Wireless receiver 22: Buffer 23: Wireless transmitter 301: Wireless communication system

Claims (5)

A wireless communication system in which the wireless connection between one wireless base station and a plurality of wireless terminals is an orthogonal frequency division multiple access (OFDMA).
The radio base station is
An information acquisition unit that acquires information on the queue length and priority in the current buffer,
A calculation unit that calculates the radio resource allocation between the wireless terminal and the wireless terminal based on OFDMA at regular time intervals using the queue length and priority information.
A feedback unit that feeds back the calculation result of the radio resource allocation to the next calculation of the radio resource allocation performed by the calculation unit.
A wireless communication system characterized by being provided with. The information acquired by the information acquisition unit is information in the buffer of the radio base station.
The wireless communication system according to claim 1, wherein the wireless resource allocation is a downlink allocation from the wireless base station to the wireless terminal. The information acquired by the information acquisition unit is information in the buffer of the wireless terminal.
The wireless communication system according to claim 1, wherein the wireless resource allocation is an uplink allocation from the wireless terminal to the wireless base station. A communication method in a wireless communication system in which a wireless connection between one wireless base station and a plurality of wireless terminals is an orthogonal frequency division multiple access (OFDMA).
Obtaining information on the queue length and priority in the current buffer of at least one of the radio base station and the radio terminal.
Using the queue length and priority information, the calculation of the radio resource allocation with the radio terminal based on OFDMA is performed at regular time intervals, and the calculation result of the radio resource allocation is used as the next radio resource allocation. To feed back to the calculation of
A communication method characterized by. A wireless base station in which the wireless connection between a plurality of wireless terminals is an orthogonal frequency division multiple access (OFDMA).
An information acquisition unit that acquires information on the queue length and priority in the current buffer of at least one of itself and the wireless terminal.
A calculation unit that calculates the radio resource allocation between the wireless terminal and the wireless terminal based on OFDMA at regular time intervals using the queue length and priority information.
A feedback unit that feeds back the calculation result of the radio resource allocation to the next calculation of the radio resource allocation performed by the calculation unit.
A radio base station characterized by being equipped with.

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