KR101909342B1 - Method for transmitting data effectively to reduce backhaul traffic in wireless network provided within aircraft - Google Patents

Abstract

The present invention relates to wireless network technology, and more particularly, to an efficient data transmission method for reducing backhaul traffic in a wireless network in an aircraft.
The present invention can help solve the inter-cell interference problem, which is one of the core problems of high reliability wireless networks in airplanes.

Description

Technical Field [0001] The present invention relates to an efficient data transmission method for reducing backhaul traffic in a wireless network in an aircraft,

The present invention relates to wireless network technology, and more particularly, to an efficient data transmission method for reducing backhaul traffic in a wireless network in an aircraft.

Private military aircraft are equipped with state-of-the-art avionics equipment to ensure the safety of air navigation, and these avionics devices are connected by wired cables and transmit relevant information. In recent years, research and standardization has been rapidly proceeding in order to reduce the weight and maintenance cost of aircraft and increase safety and reliability by constructing wireless network technology instead of existing wired communication network among aviation electronic equipment in aircraft, have.

The applications of wireless networks in such aircraft include not only infotainment but also very important applications directly related to safety such as engine control, flight control, and aircraft health monitoring. In particular, in accordance with the requirements of the advanced aviation industry, the world radiocommunication conference in 2015 has allocated a frequency of 4.2-4.4GHz internationally for wireless networks in aircraft.

Numerous wireless sensors within an aircraft communicate or receive relevant information to a central controller and / or pilot through a number of access points (APs) connected to the backhaul network. Thousands of sensors and / or actuators in aircraft have a wide variety of heterogeneous properties, from sensors that require high data rates to sensors that require low capacity transfers, depending on their characteristics.

In addition, since the sensor communication usually maintains a backup cable of 2 to 3, and the backhaul network must maintain a backup cable of 3 to 4, it is considered to be a main cause of increasing the weight of the aircraft aircraft.

The AP measures the uplink channel information using the channel transmitted from the wireless sensors and delivers it to the central network manager. The central network manager uses this to control the wireless network. The channel information of the large sensors collected by the AP is transmitted to the network manager and the air controller / pilot again, and can be connected to the latest wired backhaul network having a high-capacity transfer rate such as Ethernet-based wired communication and optical communication, .

The wireless network in the aircraft should comprehensively take into account the application requirements and the shape of the aircraft airframe, including rate, reliability, delay, scalability, and communication distance. Especially, it is very difficult to satisfy the high reliability required by applications such as aircraft control because the inside of the aircraft is made of a metallic structure.

Thus, a very dense network of thousands of wireless sensors can be reconfigured on a cell-by-cell basis for more efficient use of limited frequencies (4.2-4.4 GHz). For example, a small space such as a cockpit can be composed of one cell, and a spacious space such as a room can be configured in a multi-cell form to show a compromise between communication link reliability and data rate. However, due to the same radio frequency reuse in a plurality of cells, inter-cell interference may occur severely, which may cause a fatal problem in reliability.

In order to solve this interference problem, the uplink scheduler has been actively proposed to consider not only the strength of the self-signal of each wireless sensor received at the AP but also the strength of the interference signal caused to the adjacent AP, The contrast improvement effect was confirmed.

A typical example of a scheduling algorithm considering such interference information is a signal-to-generating interval ratio (SGIR) -based scheduling algorithm. The SGIR-based scheduling algorithm is a method of selecting a wireless sensor with the highest ratio of the interference signal intensity caused by the neighboring cell compared to the magnetic signal among the wireless sensors serviced by each AP. As the intensity of the magnetic signal increases, The lower the intensity of the interference signal, the higher the probability of being selected. In other words, even though the strength of the magnetic signal is high, the probability of selecting a wireless sensor that causes high interference in the adjacent cell is lowered by lowering the SGIR index.

However, in order to estimate the strength of the interference signal caused by each wireless sensor in each neighboring cell, it is necessary to consider all of the surrounding APs The information of the interference signal must be collected. The network manager is usually responsible for this role.

For example, in the case of the above SGIR, all the APs connected to the central network manager transmit the self-signal strength information of the wireless sensors serviced by the central network manager and the interference signal information received from the wireless sensors present in the neighboring cells thereof to the central network manager And the central network manager calculates SGIR and Generating Interference of all wireless sensors, and then performs scheduling according to a predetermined procedure.

Accordingly, as the number of APs and the number of wireless sensors increase, the amount of information to be transmitted from each AP to the central network manager increases sharply, requiring additional backhaul capacity.

1. Scheduling method and apparatus for traffic processing in a wireless backhaul network (Korean Patent Registration No. 10-1614793 (2016.04.18)

1. Pocheon-gwan, "QoS Function in Mobile Backhaul Network", The Journal of The Korea Broadcasting Engineers Society Volume 13, Issue 5 (2013. 10) pp.101-105 2. Kim, C., "A Study on the Design of Wireless Backhaul Network for PicoCell System" Dissertation (MS) KAIST 2009 Electrical and Electronics Engineering

It is an object of the present invention to provide an efficient data transmission method for reducing backhaul traffic in a wireless network in an aircraft.

Another object of the present invention is to provide an efficient data transmission method capable of solving the inter-cell interference problem, which is one of the core problems of a high reliability wireless network in an aircraft.

The present invention provides an efficient data transmission method for reducing backhaul traffic in a wireless network in an aircraft in order to achieve the above-described object.

The above-

An effective data delivery method for reducing backhaul traffic in a wireless network in an aircraft,

Transmitting a sounding signal to a plurality of access points by a plurality of wireless sensors;

Estimating channel information using the sounding signal by the plurality of access points;

Transmitting, by the plurality of access points, to a network manager for centrally controlling interference channel information in the channel information using preset thresholds;

Calculating, by the network manager, a total interference channel information amount using the interference channel information and calculating an estimated threshold value for each of the plurality of access points by applying a scheduling algorithm to the total interference channel information amount; And

And the network manager transmits the corresponding estimated threshold value to the plurality of access points, and the plurality of access points replace the estimated threshold value with the preset threshold value.

On the other hand, another embodiment of the present invention is an efficient data transmission method for reducing backhaul traffic in a wireless network in an aircraft, comprising: transmitting a sounding signal to a plurality of access points by a plurality of wireless sensors; Estimating channel information using the sounding signal by the plurality of access points; Calculating a total interference channel information amount based on interference channel information among the channel information using preset thresholds for controlling the plurality of access points in a distributed manner, applying a scheduling algorithm to the total interference channel information amount, ; And replacing the plurality of access points with the set threshold by setting the estimated threshold to the set threshold. The method of claim 1, further comprising:

Here, the channel information may include self channel information generated by the plurality of wireless sensors themselves and interference channel information generated by a neighboring wireless sensor among the plurality of wireless sensors.

The estimated threshold value may be calculated in accordance with a predetermined reference backhaul traffic capacity and an amount of calculated backhaul traffic calculated according to the total interference channel information amount.

In addition, the channel information may be uplink channel information.

Also, the scheduling algorithm may be a signal-to-generating interval ratio (SGIR) -based scheduling algorithm.

In addition, the estimated threshold is increased when the amount of the calculated backhaul traffic is larger than the predetermined reference backhaul traffic capacity and the quality of the traffic is excessive due to excessive traffic, and the calculated backhaul track ping is smaller than the predetermined reference backhaul traffic capacity And decreases when the traffic is low.

The efficient data transmission method may further include transmitting scheduling information reflecting a preset threshold value set by the plurality of access points to a corresponding one of the plurality of wireless sensors, .

 The present invention can help solve the inter-cell interference problem, which is one of the core problems of high reliability wireless networks in airplanes.

Another advantage of the present invention is that the required amount of backhaul can be reduced by drastically reducing the amount of information to be transmitted from each Access Point (AP) to the central network manager.

Another advantage of the present invention is that the interference information of the wireless sensors can be shared in real time, thereby providing a high reliability and / or low delay service required in an application in an aircraft.

1 is a block diagram illustrating a simplified configuration of a wireless network according to an embodiment of the present invention.
2 is a flowchart illustrating an efficient data transmission process for reducing backhaul traffic in a wireless network in an aircraft according to an exemplary embodiment of the present invention.
FIG. 3 is a graph illustrating a result of performance analysis of an average feedback rate when 1000 wireless sensors are connected to three access points (APs) in a 100-square-meter-wide area according to an embodiment of the present invention Graph.
4 is a graph illustrating a performance analysis of an average uplink sum rate when 1000 wireless sensors are connected to three access points (APs) in a 100-m square area of each side according to an embodiment of the present invention. Fig.
FIG. 5 is a graph illustrating a result of performance analysis of an average feedback rate when 1000 wireless sensors are connected to 10 APs (access points) in a 100-m square area of each side according to an embodiment of the present invention Graph.
FIG. 6 is a graph illustrating a performance analysis of an average uplink sum rate when 1000 wireless sensors are connected to 10 APs (access points) in a 100-m square area of each side according to an embodiment of the present invention. Fig.
7 is a detailed block diagram of the network manager 110 shown in FIG.
8 is a detailed block diagram of the access points 121 and 122 shown in FIG.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for similar elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

Hereinafter, an efficient data transmission method for reducing backhaul traffic in a wireless network in an aircraft according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 is a simplified block diagram of a wireless network 100 in accordance with an embodiment of the present invention. 1, the wireless network 100 may include a network manager 110, access points (APs) 121 and 122, wireless sensors 131, 132 and 133, and the like.

개의 액세스 포인트 AP들(121,122)이 연결되어 있으며,

개의 액세스 포인트 AP(121,122)가

개의 무선 센서(131,132,133)를 서비스하고 있다. 먼저, 모든 무선 센서들(131,132,133)은 네트워크에서 정해진 셀 선택(Cell Selection)절차에 의해서 특정 액세스 포인트 AP와 연결되어 있다. 액세스 포이트 AP와 중앙의 네트워크 매니저 간 고용량의 전송률을 보장하는 이더넷 기반의 유선 및/또는 광통신 등 백홀(backhaul)로 연결되어 있다.To the network manager 110

Access point APs 121 and 122 are connected,

The access point APs 121 and 122

And wireless sensors 131, 132, and 133 are provided. First, all the wireless sensors 131, 132, and 133 are connected to a specific access point AP by a cell selection procedure determined in the network. It is connected to backhaul such as Ethernet based wired and / or optical communication that guarantees a high-capacity transfer rate between Access Point AP and central network manager.

The set of wireless sensors connected to the cell is expressed as follows.

는 셀에 연결되어 있는 무선 센서들의 집합을 나타내고, k는 셀을 나타내고,

는 셀 k에 연결된 무선 센서를 제외한 다른 센서들의 집합을 나타내며, h_[i,j]는 무선 센서 i에서 AP j연결된 상향 채널 정보를 나타내며, g_[j,i]는 AP j에서 무선 센서 i로 연결된 하향 링크 채널 정보를 나타낸다. here,

Denotes a set of wireless sensors connected to a cell, k denotes a cell,

_{J [i, j]} represents the uplink channel information connected to the AP j in the wireless sensor i _, and g _{[j, i]} denotes the set of other sensors excluding the wireless sensor connected to the cell k. And indicates connected downlink channel information.

는 전체 무선 센서 집합을 나타낸다. 셀 k에 간섭을 야기하는 무선 센서들 중에서 주어진 임계치 보다 큰 간섭을 야기하는 무선 센서의 집합

는 다음과 같이 정의된다.Also,

Represents the entire wireless sensor set. A set of wireless sensors that cause interference greater than a given threshold among wireless sensors causing interference in cell k

Is defined as follows.

는 임계치를 나타낸다.here,

Represents a threshold value.

The information transmitted from each of the access point APs 121 and 122 to the central network manager 110 is connected to each of the access point APs 121 and 122 to transmit the self channel information of the wireless sensors 131, 132, And interfering channel information received from a wireless sensor that causes interference with itself.

First, the amount of self-channel information transmitted from the access point AP to the central network manager 110 (actual information amount should be calculated in consideration of quantization per number of times, but is defined as a number for simplification in an embodiment of the present invention) The existing total interference information feedback scheme and the scheme proposed by the present invention are calculated as follows.

는 기존의 전체 간섭 정보를 피드백 방식의 자기 채널 정보 피드백 정보량을,

는 본 발명에서 제안하는 방식의 자기 채널 정보 피드백 정보량을 나타낸다. 위의 수학식 3에서 확인할 수 있듯이, 두 방식의 자기 채널 정보 피드백을 위한 정보량은 동일하다.here,

The feedback information amount of the magnetic channel information of the feedback scheme,

Represents the amount of feedback information of the magnetic channel information proposed by the present invention. As can be seen from Equation (3) above, the amount of information for the two types of magnetic channel information feedback is the same.

On the other hand, the amount of interference signal information transmitted to the central network manager 110 from the conventional method of transmitting all the interference information to the central network manager 110 regardless of the strength of the interference signal is calculated as follows.

In the proposed method of the present invention, the total amount of interference signal information transmitted from the access point APs 121 and 122 to the network manager is as follows.

)을 다음과 같이 정의한다.Finally, the ratio of the total amount of feedback information required in the proposed method

) Is defined as follows.

2 is a flowchart illustrating an efficient data transmission process for reducing backhaul traffic in a wireless network in an aircraft according to an exemplary embodiment of the present invention. Referring to FIG. 2, the first to third wireless sensors 131, 132, and 133 transmit sounding signals to the first and second access point APs 121 and 122 to estimate the uplink channel information (step S210). Each of the access point APs 121 and 122 estimates channel information based on the sounding signal transmitted by the wireless sensors 131, 132, and 133 (step S220).

)보다 큰 간섭 채널 정보만을 중앙의 네트워크 매니저(110)로 전달한다(단계 S230). The access point APs 121 and 122 transmit the self channel information of the wireless sensors 131, 132, and 133 to the central network manager 110. On the other hand, among the interference channel information of the wireless sensors 131, 132, and 133 causing interference to the neighboring access points AP,

) To the central network manager 110 (step S230).

The central network manager 110 can calculate the total interference channel information amount (i.e., interference intensity) caused by each of the wireless sensors 131, 132, and 133 in the neighboring cells based on the interference channel information transmitted from all the access point APs 121 and 122 (Step S240).

The network manager 110 applies a scheduling algorithm to the total interference channel information amount to calculate an estimated threshold value for all users (i.e., wireless sensors) (step S240). In this case, for example, a scheduling algorithm based on SGI (Signal-to-Generating Interference Ratio) may be used. Based on the interference channel information generated by each of the wireless sensors 131, 132, and 133, an estimated Signal-to-Generating Interference Ratio Index (SGIR) can be calculated. This estimated SGIR index is the estimated threshold.

Thereafter, the network manager 110 notifies each access point AP 121 and 122 of the estimated SGIR index (i.e., a user index) (step S250). In other words, an estimated SGIR index is calculated for each access point and notified.

Then, the access points 121 and 122 select the wireless sensors 131, 132 and 133 having the largest estimated SGIR index in each cell and transmit the schedule information to transmit the data, and the corresponding wireless sensor transmits data according to the schedule information Steps S260 and S270).

The role of the network manager 110 is to accurately calculate the GI (Generating Interference) that each sensor will cause to neighboring APs. Based on this value, various scenarios are possible for scheduling.

First, when each access point receives the channel information from the sensors it serves, it can know the information of the magnetic signal channel. Therefore, after receiving the GI values of the respective sensors from the network manager, the sensors having the maximum SGIR can be selected after calculating the SGIR of each sensor.

In this case, each AP does not need to feed back the channel information received from its own sensors to the network manager.

Second, each access point feeds back both the signaling channel information measured from the sensors it serves and the interference information measured from the sensors belonging to the adjacent access point. Then, the network manager 110 can calculate the SGIR value of all the sensors, and notify only the user index having the maximum SGIR value for each AP.

FIG. 3 is a graph illustrating a result of performance analysis of an average feedback rate when 1000 wireless sensors are connected to three access points (APs) in a 100-square-meter-wide area according to an embodiment of the present invention Graph. Referring to FIG. 3, the horizontal axis represents the threshold value (dBm) and the vertical axis represents the average feedback rate. Also, an SGIR curve 310 and a general SGIR curve 320 according to an embodiment of the present invention are compared.

4 is a graph illustrating a performance analysis of an average uplink sum rate when 1000 wireless sensors are connected to three access points (APs) in a 100-m square area of each side according to an embodiment of the present invention. Fig. Referring to FIG. 4, the horizontal axis represents the threshold value (dBm) and the vertical axis represents the average uplink sum rate. Also, an ideal SGIR curve 410, an SGIR curve 420 according to one embodiment of the present invention, and a general SGIR curve 430 are shown for comparison.

)가 높아질수록 기존 방식 대비 제안 방식의 피드백 비율은 낮아짐을 확인할 수 있다. 구체적으로, 임계치를 약 ∼40dBm으로 설정할 경우 기존 방식대비 데이터 전송용량의 감소는 없으면서 백홀 트래픽을 약 20%절감할 수 있다.Referring to Figures 3 and 4,

), The feedback ratio of the proposed method is lower than that of the conventional method. Specifically, if the threshold value is set to about ~ 40 dBm, the backhaul traffic can be reduced by about 20% without decreasing the data transmission capacity compared to the existing method.

FIG. 5 is a graph illustrating a result of performance analysis of an average feedback rate when 1000 wireless sensors are connected to 10 APs (access points) in a 100-m square area of each side according to an embodiment of the present invention Graph. Referring to FIG. 5, the horizontal axis represents the threshold value (dBm) and the vertical axis represents the average feedback rate. Also, an SGIR curve 510 and a general SGIR curve 520 according to an embodiment of the present invention are compared.

FIG. 6 is a graph illustrating the performance of the average uplink sum rate when a 1000 wireless sensor is connected to ten APs (access points) in a 100-m square area of each side according to an embodiment of the present invention. FIG. Referring to FIG. 6, the horizontal axis represents the threshold value (dBm) and the vertical axis represents the average uplink sum rate. Also, an ideal SGIR curve 610, an SGIR curve 620 according to one embodiment of the present invention, and a general SGIR curve 630 are shown for comparison.

Referring to FIG. 5 and FIG. 6, when the threshold is set to about ~ 20 dBm, the backhaul traffic can be reduced by about 65% without decreasing the data transmission capacity compared to the existing scheme.

7 is a detailed block diagram of the network manager 110 shown in FIG. 7, the measuring unit 710 measures the amount of traffic received from the access points 121 and 122 connected to the access point 121 and 122, the interference channel information transmitted through the access points 121 and 122, A first threshold value setting unit 730 for calculating a threshold value using the interference amount of each of the wireless sensors 131, 132, and 133 calculated by the calculation unit 720, A controller 740 for controlling functions of the manager 110 and signals between the elements, and the like.

Of course, the network manager 110 transmits the amount of interference to the access point APs 121 and 122 to perform a scheduling algorithm in each access point AP 121 and 122, or performs a scheduling algorithm directly in the central network manager 110 And may only deliver the final result for each access point AP (121, 122).

In addition, the calculation unit 720 may calculate the interference amount caused by each wireless sensor toward the adjacent access point AP by collecting the interference channel information collected from each access point AP (121, 122).

Also, the measuring unit 710 can measure the amount of backhaul traffic received from each of the access point APs 121 and 122.

The control unit 740 may transmit the threshold modification command to each of the access point APs 121 and 122 in consideration of the capacity of the backhaul traffic and the amount of the backhaul traffic measured by the measurement unit 710. [ The measurement unit 710 may request the access point APs 121 and 122 to increase the threshold value when the traffic is excessive due to excessive traffic due to the backhaul capacity and if the traffic is low compared to the backhaul capacity, 121, 122 to lower the threshold.

8 is a detailed block diagram of the access points 121 and 122 shown in FIG. Referring to FIG. 8, the access point APs 121 and 122 may include a channel estimator 810, a processor 820, a threshold setting unit 830, and the like.

The channel estimation unit 810 receives sounding signals from the wireless sensors 131, 132, and 133, and estimates corresponding channel information based on the sounding signals. In addition, the access point APs 121 and 122 receive the sounding signals transmitted by all the wireless sensors, including the wireless sensors 131, 132, and 133, which are serviced by the access point APs 121 and 122, and estimate the channel information.

The processing unit 820 receives the channel information from each of the access point APs 121 and 122 through the sounding signal transmitted from the wireless sensors 131, 132, and 133 directly served by the channel estimation unit 810, . In addition, interference signals are estimated from the sounding signals transmitted by wireless sensors that cause interference to themselves except for the wireless sensors, and the signal intensity of the estimated interference channel information is compared with a preset threshold value. Therefore, only the interference channel information larger than the set threshold value is selected and transmitted to the central network manager 110.

The second threshold setting unit 830 may adaptively modify and / or optimize the threshold value set in the processing unit 820 of each access point AP 121 and 122 according to the channel conditions. Of course, the second threshold value setting unit 830 performs the same function and role as the first threshold value setting unit 730 shown in FIG. 7, and the configuration may be omitted. In detail, the second threshold value setting unit 830 If the second threshold setting unit 830 is not configured in the access point AP, the first threshold value setting unit 830 may be configured to perform the first And may be operated centrally through the threshold setting unit 730. [

The term " part "in the specification refers to a unit for processing at least one function or operation, which may be implemented by hardware, software, or a combination of hardware and software. In particular, in hardware implementation, an application specific integrated circuit (ASIC), a digital signal processing (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA) A microprocessor, another electronic unit, or a combination thereof. In software implementation, it may be implemented as a module that performs the above-described functions. The software may be stored in a memory unit and executed by a processor. The memory unit or processor may employ various means well known to those skilled in the art.

100: Wireless network
110: Network Manager,
121, 122: first to second access points
131, 132, 133: first to third wireless sensors
710:
720:
730: first threshold value setting unit
740:
810: Channel estimation unit
820:
830: second threshold value setting unit

Claims (8)

An efficient data transmission method for reducing backhaul traffic by reducing the amount of information to be transmitted from a plurality of access points constituting a wireless network in an aircraft to a central network manager,
Transmitting a sounding signal to a plurality of access points by a plurality of wireless sensors;
Estimating channel information using the sounding signal by the plurality of access points;
Transmitting, by the plurality of access points, to a network manager for centrally controlling interference channel information in the channel information using preset thresholds;
Calculating, by the network manager, a total interference channel information amount using the interference channel information and calculating an estimated threshold value for each of the plurality of access points by applying a scheduling algorithm to the total interference channel information amount; And
When the network manager transmits the corresponding estimated threshold to the plurality of access points, the plurality of access points replace the estimated threshold with the set threshold,
Wherein the channel information includes self channel information generated by the plurality of wireless sensors themselves and interference channel information generated by a neighboring wireless sensor among the plurality of wireless sensors,
The channel information is uplink channel information,
Wherein the plurality of access points transmit all of the magnetic signal information of the plurality of wireless sensors to the network manager,
Wherein the estimation threshold is calculated in accordance with a preset reference backhaul traffic capacity and an amount of calculated backhaul traffic calculated according to the total interference channel information amount,
Wherein the estimated threshold value is increased when the amount of the calculated backhaul traffic is greater than the predetermined reference backhaul traffic capacity and the quality of the traffic is excessive due to excessive traffic and the amount of the calculated backhaul traffic is smaller than the predetermined reference backhaul traffic capacity, The method comprising the steps of: a) providing an effective data transmission method for reducing backhaul traffic in a wireless network in an aircraft,
delete delete delete delete The method according to claim 1,
Wherein the scheduling algorithm is a signaling-to-generating interval ratio (SGIR) -based scheduling algorithm.
delete The method according to claim 1,
And transmitting the scheduling information to the wireless sensor of the plurality of wireless sensors, wherein the wireless sensor is configured to transmit the scheduling information to the wireless sensor, A method for efficient data transmission for reducing backhaul traffic in a network.

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