JP2014179861A - Radio communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve both reduction in consumption power and high-speed communication in a radio communication device.SOLUTION: A radio communication device of the invention comprises: a radio communication control unit for controlling operation to transmit and receive signals by a plurality of radio communication circuits at the same time at the same frequency band; a radio communication monitoring unit for storing the characteristics of signals transmitted and received by the radio communication circuits; and a state control unit for selecting the number of RF chains used for transmission and reception of signals on the basis of the signal characteristics of the transmitted and received signals. The radio communication control unit calculates an estimated value of consumption power efficiency by a preset calculation formula in the case where signals are transmitted and received, per transmission rate associated with the selected number of RF chains, by the transmission rate and the number of RF chains, and selects a transmission rate to transmit and receive signals on the basis of the estimated value.

Description

  The present invention relates to a wireless communication device, and more particularly to a wireless communication device capable of transmitting and receiving data using a plurality of wireless communication circuits.

  In a wireless communication system, transmission rate control is an essential function in order to realize a wide communication area and high-speed communication. For example, use as fast a transmission rate as possible for communication with wireless terminals at a short distance, and use a low transmission rate for communication with long-distance wireless terminals. Transmission rate control that provides reliable wireless communication is common. Such a transmission rate control method uses the fastest transmission rate within a communicable range.

  On the other hand, there is an urgent need to reduce power consumption as a global warming prevention measure and a power demand reduction measure on a global level. In the wireless communication system as described above, the power efficiency is maximized by using the fastest transmission rate.

  However, in a wireless communication system that supports MIMO (Multiple Input Multiple Output) typified by IEEE802.11n, power efficiency is not necessarily improved by using a high transmission rate. This is because a radio base station that supports the MIMO communication scheme uses a plurality of radio communication circuits (RF chains) that have been one so far in order to realize a high transmission rate.

  In Non-Patent Document 1, in IEEE802.11n, even if the number of MIMO spatial multiplexing increases, the power does not simply double, the high-speed transmission rate is not always high in power efficiency, It always shows that operation with a single RF chain is the most power efficient.

  Further, in Non-Patent Document 2, in the IEEE802.11n communication method using MIMO, it is not always optimal to use a high transmission rate, and the optimal setting is a signal-to-noise ratio (in wireless communication) ( SNR), communication traffic pattern, transmission rate, and the spatial multiplexing number of MIMO have been reported to change dynamically.

  As a result of the above problems, in wireless communication systems that use MIMO, the power efficiency during communication is not optimal due to the interaction of the wireless communication environment, communication usage status, and transmission rate, resulting in increased power consumption. It becomes.

D. Halperin, B. Greenstein, A. Sheth, and D. Wetherall, "Demystifying 802.11n power consumption," Proc. HotPower 2010, p.1, Oct. 2010 I. Pefkianakis, SB Lee, and S. Lu, "MIPS: MIMO power save in 802.11n wireless networks," UCLA, Comput. Sci. Dept., Los Angeles, CA, Tech. Rep. TR-100040-2010, 2010 .

  Under these circumstances, in order to achieve both reduction of power consumption and provision of high-speed communication, the wireless LAN (Local Area Network) router product, which is a type of commercially available wireless base station, has a power saving mode. There is an installed product.

  In the power saving mode, only one chain that is required for communication is used at least among the RF chains installed in multiple radio base stations, and the other chains are not used (low power state or power off). By doing so, power consumption is reduced. In such a case, for example, when a radio base station having two RF chains is used and the power saving mode is used and the number of RF chains is set to one, the upper limit of the transmission rate is half of the normal rate. You must allow that.

  It is also possible to switch between using and not using the power saving mode according to a schedule designated in advance by the user, or switching between using and not using the power saving mode when a wireless communication user appears. However, it is not possible to automatically use a transmission rate that optimizes power efficiency in accordance with a wireless communication environment such as SNR during wireless communication.

  From the above, in radio base stations that use the MIMO communication method, the number of RF chains and the transmission rate according to the radio communication environment and communication usage status cannot be automatically selected, reducing power consumption and high-speed communication. There was a problem that it was not possible to achieve both. In addition to the MIMO communication system radio base station, a problem arises in that it is not possible to achieve both reduction in power consumption and high-speed communication in any radio communication apparatus as described above.

  For this reason, an object of the present invention is to solve the above-described problem that it is impossible to achieve both reduction in power consumption and high-speed communication in a wireless communication device.

A wireless communication device according to one aspect of the present invention
A wireless communication control unit that controls the operation of transmitting and receiving signals simultaneously with a plurality of wireless communication circuits in the same frequency band;
A wireless communication monitoring unit that detects characteristics of signals transmitted and received by the wireless communication circuit and stores them in a signal characteristic database as signal characteristic information;
A transmission rate table in which the number of RF chains representing the number of the wireless communication circuits and the transmission rates that can be used when transmitting and receiving signals with the wireless communication circuits of the number of RF chains are stored in association with each other;
A state control unit that selects the number of RF chains used for signal transmission and reception based on signal characteristic information of transmitted and received signals stored in the signal characteristic database;
The wireless communication control unit acquires the transmission rate associated with the number of RF chains selected by the state control unit from the transmission rate table, and uses the transmission rate and the number of RF chains for each transmission rate. Calculate an estimated value of power consumption efficiency when a signal is transmitted and received by a preset calculation formula, and select a transmission rate for transmitting and receiving the signal based on the estimated value.
The configuration is as follows.

Moreover, the program which is the other form of this invention is:
Wireless communication device
A wireless communication control unit that controls the operation of transmitting and receiving signals simultaneously with a plurality of wireless communication circuits in the same frequency band;
A wireless communication monitoring unit that detects characteristics of signals transmitted and received by the wireless communication circuit and stores them in a signal characteristic database as signal characteristic information;
A state control unit that selects the number of RF chains used for signal transmission and reception based on signal characteristic information of transmitted and received signals stored in the signal characteristic database;
And realize
The wireless communication control unit stores the transmission stored in association with the number of RF chains representing the number of the wireless communication circuits and the transmission rate that can be used when signals are transmitted and received by the wireless communication circuits of the number of RF chains. The power consumption when acquiring the transmission rate associated with the number of RF chains selected by the state control unit from the rate table and transmitting / receiving signals at the transmission rate and the number of RF chains for each transmission rate Calculating an estimated value of efficiency by a preset calculation formula, and selecting a transmission rate for transmitting and receiving signals based on the estimated value;
It is a program for realizing this.

In addition, a wireless communication method according to another aspect of the present invention includes:
In a wireless communication device including a wireless communication control unit that controls the operation of transmitting and receiving signals simultaneously with a plurality of wireless communication circuits in the same frequency band,
Detect the characteristics of the signal transmitted and received by the wireless communication circuit, store it in the signal characteristics database as signal characteristics information,
Based on the signal characteristic information of the transmitted and received signals stored in the signal characteristic database, select the number of RF chains used for signal transmission and reception,
The number of RF chains representing the number of the wireless communication circuits and the transmission rate that can be used when signals are transmitted / received by the wireless communication circuits of the number of RF chains are selected from the transmission rate table stored in association with each other. The transmission rate associated with the number of RF chains obtained is obtained, and an estimated value of power consumption efficiency when a signal is transmitted and received at the transmission rate and the number of RF chains for each transmission rate is calculated using a preset calculation formula And selecting a transmission rate for transmitting and receiving signals based on the estimated value.
The configuration is as follows.

  By configuring as described above, the present invention can achieve both reduction in power consumption and high-speed communication in a wireless communication device.

It is the schematic which shows the whole structure of the radio | wireless communications system in Embodiment 1 of this invention. It is a block diagram which shows the structure of the wireless base station disclosed in FIG. It is a figure which shows an example of the transmission rate table memorize | stored in the wireless base station disclosed in FIG. It is a figure which shows an example of the transmission rate table memorize | stored in the wireless base station disclosed in FIG. It is a figure which shows an example of the transmission / reception radio | wireless frame table memorize | stored in the radio base station disclosed in FIG. It is a figure which shows the mode of the state transition of the wireless base station disclosed in FIG. 3 is a flowchart illustrating an operation when selecting the number of RF chains in the radio base station disclosed in FIG. 2. 3 is a flowchart showing an operation when a transmission rate is selected in the radio base station disclosed in FIG. 2. 3 is a flowchart showing an operation when a transmission rate is selected in the radio base station disclosed in FIG. 2. It is a figure which shows the calculation formula of the power consumption estimation model used in the radio base station disclosed in FIG. It is a figure which shows the measured value of the power consumption for every transmission rate in the radio base station disclosed in FIG. FIG. 3 is a diagram showing a comparison between an actual measurement value of power consumption for each transmission rate and a calculated value using a power consumption estimation model in the radio base station disclosed in FIG. 2. FIG. 3 is a diagram showing a comparison between an actual measurement value of power consumption for each transmission rate and a calculated value using a power consumption estimation model in the radio base station disclosed in FIG. 2. It is a block diagram which shows the structure of the wireless base station in Embodiment 2 of this invention. It is a figure which shows an example of the transmission / reception radio | wireless frame table memorize | stored in the radio base station disclosed in FIG. It is a figure which shows the mode of the state transition of the radio base station disclosed in FIG. It is a figure which shows the mode of an example when selecting the number of RF chains in the wireless base station disclosed in FIG. It is a figure which shows the table used in the other example when selecting the number of RF chains in the radio base station disclosed in FIG. It is a block diagram which shows the structure of the radio | wireless communication apparatus in attachment 1 of this invention.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. 1 to 4 are diagrams illustrating the configuration of the wireless communication system, and FIGS. 5 to 9 are diagrams illustrating the operation of the wireless communication system.

  FIG. 1 is a schematic diagram of a wireless communication system in the present embodiment. The wireless communication system includes a wireless base station 1, a wireless terminal 2, and a backbone network N. The wireless base station 1 (wireless communication apparatus) in the present embodiment uses a MIMO communication method in which signals are transmitted and received by a plurality of wireless communication circuits (RF chains) simultaneously in the same frequency band. The wireless terminal 2 transmits / receives a communication packet to / from the backbone network N via the wireless base station 1. In FIG. 1, only one wireless terminal 2 belongs to the wireless base station 1, but the number of wireless terminals 2 is not limited to one and may be plural.

  In the present embodiment, a MIMO communication system radio base station will be described as an example of a radio communication apparatus. However, the radio communication apparatus is not limited to being a radio communication base station. For example, the wireless communication device can be applied to a wireless terminal using the MIMO communication method, and may be another wireless communication device. For example, in the IEEE802.11n communication system, SMPS (Spatial Multiplexing Power Save) defined for wireless terminals can reduce power consumption by changing the number of RF chains, but compatibility with high-speed communication is not considered. By using the present invention, it is possible to achieve both a reduction in power consumption superior to SMPS and high-speed communication.

  FIG. 2 is a functional block diagram showing the configuration of the radio base station 1 in the present embodiment. As shown in this figure, the radio base station 1 includes a radio communication control unit 11, a plurality of RF chain units 12, another communication control unit 13, a radio communication monitoring unit 14, a state control unit 15, and a power consumption estimation model calculation unit. 16 and a database (DB) 20. The radio base station 1 is configured by an information processing device including an arithmetic device and a storage device, and the above-described units 11 to 16 are constructed by incorporating a program into the arithmetic device.

  The wireless communication function unit 11 can control use / unuse of the RF chain unit 12 based on information notified from the state control unit 15 and the power consumption estimation model calculation unit 16. That is, as will be described later, the wireless communication function unit 11 controls the number of RF chains used for wireless communication and the transmission rate. In addition, the other communication control unit 13 may have a function of controlling communication to a mobile phone network such as a wired LAN, 3G, LTE, WiMAX, or the like. The packet is transferred between the wireless communication control unit 11 and the other communication control unit 13.

  Next, a specific configuration and operation of the radio base station 1 will be described. In this embodiment, the case where the upper limit of the MIMO spatial multiplexing number, that is, the minimum value of the minimum number of RF chains used simultaneously in the same frequency band is “2” will be described as an example. However, the upper limit of the number of RF chains may be a value larger than “2”.

  FIG. 3A shows a transmission rate table in which the number of RF chains that can be used by the radio base station 1 and the transmission rate are associated with each other. This transmission rate table is stored in advance in the DB 20 and used by the state control unit 15 and the power consumption estimation model calculation unit 16 as described later. Specifically, the transmission rate table has information on a transfer rate (transmission rate) indicating a data transfer amount per second and a MIMO spatial multiplexing number (RF chain number) for one transmission rate.

  In this embodiment, an upper limit of the number of MIMO spatial multiplexing is “2”, and a transmission rate table when 16 types of transmission rates are available is shown. “Transmission rate table 0” shown in FIG. This is a list of all transmission rates with multiplexing numbers “1” and “2”. The “transmission rate table 1” shown in FIG. 3B (1) lists the transmission rates with the MIMO spatial multiplexing number “1”, and the “transmission rate table 2” shown in FIG. The transmission rates with the MIMO spatial multiplexing number “2” are listed. As described above, in the present embodiment, the transmission rate table is stored in the DB 20 in advance, separately for each MIMO spatial multiplexing number. However, a table in which all transmission rates are listed may be generated for each MIMO spatial multiplexing number as necessary. The upper limit of the MIMO spatial multiplexing number is not limited to “2”, and the transmission rate types are not limited to 16 types.

  FIG. 4 is a diagram illustrating an example of a “transmission / reception radio frame table” stored in the DB 20. Each time a wireless frame is transmitted / received via the RF chain 12, the wireless communication monitoring unit 14 acquires a received strength (RSSI: Received Signal Strength Indicator) at that time from the wireless communication control unit 11 and stores it in the DB 20. In the present embodiment, the RSSI of the transmitted / received frame is stored in the transmitted / received frame table. However, as shown in the second embodiment, information indicating other signal characteristics of the transmitted / received frame may be detected and stored. Good.

  FIG. 5 is a diagram illustrating an example of state transition of the radio base station 1 by the state control unit 15. The radio base station 1 shown in FIG. 5B has an initial state, a standby state, a communication state, and a power saving state. The “initial state” is a state in which power is supplied to the wireless base station 1 and preparations are being made for providing wireless communication capability, and wireless communication is not possible. The “standby state” is a state in which wireless communication capability is provided but communication is not actually performed, and wireless communication itself is possible. The “communication state” is a state in which wireless communication capability is provided and wireless communication is possible while wireless communication is being performed. The “power saving state” is a state in which power consumption is reduced as compared with the standby state and communication is not actually performed, and wireless communication itself may be possible or impossible.

  Then, the radio base station 1 shown in FIG. 5B sets the number of RF chains as described later in the state illustrated by the elliptical dotted line. For example, the number of RF chains is set at each timing of transition from the initial state to the standby state, transition between the standby state and the power saving state, and standby state.

  As shown in FIG. 5A, the radio base station 1 does not have to have a “power saving state”. In this case, the number of RF chains is set at each timing of transition from the initial state to the standby state and in the standby state.

  Next, processing at the time of state transition by the state control unit 15 will be described with reference to the flowchart of FIG. At the time of the state transition, first, the radio base station 1 confirms whether the RF chain power saving control is valid (On) (step S1). When the RF chain power saving control is invalid (when it is Off) (step S1: No), the state control unit 15 uses “all RF chains” for the wireless communication control unit 11, and “ Use of transmission rate table 0 ”is notified (step S6).

  When the RF chain power saving control is effective (when it is On) (step S2: Yes), the RSSI of an arbitrary frame is acquired from the DB 20, and the average value is calculated as the average RSSI (step S2). At this time, as the RSSI of an arbitrary frame acquired from the DB 20, for example, the RSSI of the frame acquired per unit time immediately before (latest) is used. However, the RSSI for calculating the average is not limited to the above.

  Next, it is checked whether or not the calculated average RSSI value is smaller than the average RSSI1 chain utilization threshold preset in the radio base station 1 (step S3). When the average RSSI value is smaller than the average RSSI1 chain usage threshold (step S3: Yes), the state control unit 15 selects “1” as the number of RF chains. Then, the state control unit 15 notifies the wireless communication control unit 11 that “one RF chain” is used and “the transmission rate table 1” corresponding to the number of RF chains “1” is used. (Step S4).

  When the average RSSI value is equal to or greater than the average RSSI1 chain usage threshold (step S3: No), the state control unit 15 selects “2” as the number of RF chains. Then, the state control unit 15 notifies the wireless communication control unit 11 that “two RF chains” are used and that “transmission rate table 2” corresponding to the number of RF chains “2” is used. (Step S5).

  FIG. 7 is a flowchart showing transmission rate selection processing by the wireless communication control unit 11. First, with reference to FIG. 7A, processing contents when the wireless communication control unit 11 receives a transmission rate table notification from the state control unit 15 will be described.

When receiving the notification of the transmission rate table from the state control unit 15, the wireless communication control unit 11 reads out the corresponding transmission rate table from the DB 20 and inputs it (step S11). Then, information is input to the power consumption estimation model calculation unit 16 for each input transmission rate, and a power consumption efficiency value is calculated as power consumption per bit by a calculation formula based on a preset power consumption estimation model. (Step S12). The calculation formula of the power consumption estimation model is shown in FIG. 8 and the following formula (1).
Em = N · (Pcd + Pa · Ra) + Pd · Sm (1)

  The above-described calculation formula (1) is: MIMO spatial multiplexing number N, Pcd representing energy consumed during spatial propagation, Pa representing power consumption of one RF chain, Ra representing operation rate of one RF chain, standby state Pd representing the power consumption of the wireless communication control unit 11 and the transfer rate Sm. The power consumption value Em can be estimated by inputting the number of RF chains to be used for N, a realistic power consumption value for Pcd and Pa, and an operation rate value for Ra. The parameter values described above may be fixed values or may be calculated using another calculation formula.

  Then, after calculating the power consumption efficiency value (power consumption per bit) for each transmission rate in the transmission rate table that received the notification, the power efficiency becomes maximum, that is, the power consumption per bit is minimum. Is selected as the transmission rate to be used (step S13). The selection of the transmission rate is not limited to the method described above, and may be selected by another method.

  Next, referring to FIG. 7B, processing contents other than when the notification of the transmission rate table is received from the state control unit 15 are shown. The wireless communication control unit 11 performs a conventional rate selection process (that is, a rate selection process that is normally installed in the wireless base station 1), and selects one transmission rate (step S21). If the selected transmission rate is changed from the previously selected transmission rate (the last used transmission rate) (step S22: Yes), a transmission rate having a transfer speed equal to or lower than the selected transmission rate is selected. The available transmission rate is set (step S23), and the transmission rate that minimizes the power consumption per bit is selected from the available transmission rates (step S24). If the selected transmission rate has not been changed from the previously selected transmission rate, the transmission rate selected by the conventional rate selection process (that is, the previously selected transmission rate) is selected (step S25).

  In the above, a method using both conventional rate selection processing and model estimation has been described. However, a method may be used in which a transmission rate is selected only by a power consumption estimation model without using conventional rate selection. .

  FIG. 9 shows a graph comparing actual measurement values, model calculation values, and actual measurement values in an actual IEEE802.11n radio base station. The power consumption graph of FIG. 9A is a value obtained by measuring the power consumption by setting the number of RF chains and the transmission rate of an IEEE802.11n radio base station that actually has a maximum of 2 RF chains. Transmission rate numbers 0 to 7 are measured values when the number of RF chains is 1, and transmission rate numbers 8 to 15 are measured values when the number of RF chains is 2. From this figure, it can be seen that the power consumption value has almost no influence on each transmission rate and is almost determined by the influence of the number of RF chains.

  FIG. 9B is a graph in which the power consumption efficiency is calculated as the power consumption per bit and compared with the actual measurement value. In this graph, the smaller the value of the power consumption per bit that is the value on the vertical axis, the higher the power efficiency. According to this graph, it can be seen that the value in the power consumption estimation model is not significantly different from the actually measured value, and the tendency of the power consumption efficiency for each transmission rate can be accurately estimated. Therefore, as shown by the dotted line in FIG. 9C, the transmission rates such as transmission rate numbers 4 to 7 and transmission rate numbers 12 to 15 having high power efficiency are positively selected by the processing shown in FIGS. 6 and 7 described above. Is done.

  As described above, the radio base station according to the present embodiment can automatically set one chain with low power consumption and provide high-speed communication according to the radio communication environment, that is, the RSSI value of the transmission / reception frame. It becomes possible to operate by switching settings. In communication, a transmission rate with low power consumption per bit, that is, high power efficiency can be automatically selected. As a result, the radio base station can provide high-speed communication capability while automatically reducing power consumption.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIGS. 10 to 11 are diagrams for explaining the configuration of the radio base station in the second embodiment, and FIGS. 12 to 13 are diagrams for explaining the operation of the radio base station. FIG. 14 is a diagram illustrating another configuration of the radio base station.

  As shown in FIG. 10, the radio base station 1 in the present embodiment includes a statistical processing unit 17 in addition to the configuration in the first embodiment described above. As will be described later, the statistical processing unit 17 statistically estimates the wireless communication environment and the communication usage status based on the information stored in the DB 20. The radio base station 1 is configured to select the number of RF chains and the transmission rate in accordance with the radio communication environment and the communication usage situation estimated by the statistical processing unit 17.

  Next, a specific configuration and operation of the radio base station 1 in the present embodiment will be described with reference to FIGS. 11 to 14. In this embodiment, the case where the number of RF chains is “2” will be described. However, the number of RF chains may be larger than “2”.

  FIG. 11 shows information held by the DB 20. The transmission / reception radio frame table stored in the DB 20 in the present embodiment is information related to the received signal registered in the radio communication monitoring unit 14, and in addition to the RSSI described with reference to FIG. , Ack, frame size, and transfer rate information. Here, the time stamp represents the date and time when the frame was transmitted and received. Ack represents ok when the radio frame has been successfully transmitted and received, and ng when it has failed. The frame size represents the data size of the transmitted / received frame. The transfer rate represents the value of the transfer rate in the transmission rate table. In addition, the value of the said transmission / reception radio | wireless frame table | surface is used by calculation of the statistical process part 17, so that it may mention later.

  FIG. 12 shows an example of state transition of the wireless communication terminal 1 by the state control unit 15. The state control unit 15 may be configured to set the number of RF chains between the state transitions between the standby state and the communication state as indicated by an elliptical dotted line in addition to the state transitions of FIG.

  Next, calculation processing by the statistical processing unit 17 will be described. The statistical processing unit 17 performs a statistical calculation process on the frame information for the corresponding time stored in the DB 20 for each unit time. For example, the unit time may be specified as 1 second, 1 minute, 1 hour, or 1 day. When the unit time is 1 second, the frame that is the object of calculation of one calculation process is the information from all the information held in the DB 20 up to the current time starting from 1 second before the current time. A frame corresponding to one second is specified from the time stamp information. Note that the statistical processing unit 17 may perform calculation processing not only for one unit time at a time but also for a plurality of unit times at a time.

  The statistical processing unit 17 calculates the number of frames, average RSSI, average FER, average frame size, and average throughput for each unit time, and notifies the state control unit 15 of the values. Here, the number of frames is the number of frames in the corresponding unit time, the average RSSI is the average value of RSSI of all frames in the corresponding unit time, and the average FER is the ratio of Ack ok of all frames in the corresponding unit time. The average frame size is an average value of the frame sizes of all the frames within the corresponding unit time, and the average throughput is an average value of the throughput of all the frames within the corresponding unit time.

  As described above, the statistical processing unit 17 calculates the statistical value of the signal characteristic information, such as the average value of the RSSI and the frame size indicating the characteristic of the signal transmitted and received by the radio base station 1. Based on the statistical value, the number of RF chains is selected by the state control unit 15 as will be described later. Note that the value calculated by the statistical processing unit 17 is not limited to the signal characteristics described above, and values representing other characteristics may be calculated.

  FIG. 13 shows a state at the time of state transition in the state control unit 15. The state control unit 11 selects the number of RF chains using a method for determining the number of RF chains based on a defined rule, instead of the process for determining the number of RF chains in FIG.

  An example of the rule will be described with reference to FIG. First, here, it is assumed that the number of frames per unit time is calculated by the statistical processing unit 17 as shown in FIG. Then, for each unit time, the state control unit 15 determines the number of RF chains as follows.

  When the value of the number of frames becomes equal to or less than the “frame number 1 chain lower threshold” specified in advance (see arrow Y1 in FIG. 13), the state control unit 15 sends the number of RF chains “ 1 ”is notified. Further, the state control unit 15 notifies the wireless communication control unit 11 of the number of RF chains “2” when the value becomes equal to or higher than the “frame 1 chain upper threshold value” specified in advance (see arrow Y2 in FIG. 13). The rule for determining the number of RF chains by the state control unit 15 in this case is the following rule 1.

(Rule 1)
if "number of frames"> = number of frames 1 chain upper threshold, then 2 chains set in wireless communication controller
if "number of frames"<= number of frames 1 chain lower threshold, then set 1 chain in wireless communication controller

  Note that the rules for determining the number of RF chains by the state control unit 15 are not limited to the rules described above. The statistical result of the statistical processing unit 17 used in the rule is not limited to the number of frames, and may be a rule using average RSSI, average FER, average frame size, and average throughput. That is, the number of RF chains may be determined according to whether average RSSI, average FER, average frame size, and average throughput are equal to or greater than a preset threshold value. Other examples of rules are shown below.

(Rule 2)
if "average RSSI"> = average RSSI 1 chain upper threshold, then set 2 chains in wireless communication controller
if "average RSSI"<= average RSSI 1 chain lower threshold, then set 1 chain in the wireless communication control (rule 3)
if "average FER"> = average FER1 chain upper threshold, then set 2 chains in the wireless communication controller
if "Average FER"<= Average FER1 chain lower threshold, then 1 chain set in the wireless communication control unit (Rule 4)
if "average rate"> = average rate 1 chain upper threshold, then 2 chains set in wireless communication controller
if "average rate"<= average rate 1 chain lower threshold, then 1 chain set in the wireless communication controller

The state control unit 15 may select and use each of the rules described above according to the situation, or may use a combination of a plurality of rules. For example, when the following rule 5 is set, 2 chains are set when the number of frames and the average RSSI are equal to or greater than the “1 chain upper threshold value” set for each, and “1 chain” is set. One chain is set when the value is equal to or lower than the “lower threshold value”.
(Rule 5)
Rule 1 (number of frames) & Rule 2 (RSSI)

  Next, referring to FIG. 15, another example of processing at the time of state transition in the state control unit 15 will be shown. The state control unit 15 can use a method of determining the number of RF chains based on the truth table instead of the process of determining the number of RF chains in FIG.

  An example of the truth value table will be described with reference to FIG. The input values of the truth table are 0 and 1 values based on RSSI, Ack, throughput, and power saving designation, and the output values are 0 and 1 values representing 1 chain and 2 chains. Specifically, input values and output values are defined as follows.

(Input value)
"RSSI"
0: Average RSSI is below average RSSI 1 chain threshold 1: Average RSSI is above average RSSI 1 chain threshold “Ack”
0: Average FER is greater than or equal to average FER1 chain threshold 1: Average FER is less than average FER1 chain threshold “throughput”
0: The average throughput is less than the average throughput 1 chain threshold 1: The average throughput is greater than or equal to the average throughput 1 chain threshold “Power Saving Setting”
0: No power saving required 1: Power saving required

(Output value)
"One chain"
0: 1 Chain setting not used 1: 1 chain setting used “2 chains”
0: Do not use 2 chain setting 1: Use 2 chain setting

  The above definition will be described in detail. First, the input value “RSSI” of the truth table is set to “0” when the average RSSI that is the calculation result of the statistical processing unit 17 is less than a predetermined RSSI1 chain threshold. It is set to “1” when it is equal to or more than the determined RSSI 1 chain threshold. The input value “Ack” in the truth table is “0” when the average FER that is the calculation result of the statistical processing unit 17 is equal to or greater than the predetermined average FER1 chain threshold, and is less than the predetermined average FER1 chain threshold. “1” is set at a certain time. The input value “throughput” of the truth table is “0” when the average throughput, which is the calculation result of the statistical processing unit 17, is less than the predetermined average throughput 1 chain threshold, and is equal to or greater than the predetermined average throughput 1 chain threshold. Is set to “1”. The input value “power saving designation” of the truth value table designates “0” when there is no power saving request from the administrator of the radio base station 1 and “1” when there is a power saving request.

  However, another value calculated by the statistical processing unit 17 may be used as the input value. For example, the power saving designation may be given in the form that the administrator of the radio base station 1 designates the radio base station 1 directly. Further, according to the state information indicating the state of the wireless base station 1, for example, when the wireless base station 1 is configured to have a battery, 0 is set according to the value of “remaining battery” (state information). , 1 may be determined. Further, the output value of the truth table may be more than two chains.

  The state control unit 15 determines 0 or 1 for the value notified from the statistical processing unit 17 and sets it as the input value of the truth value table. Then, the state control unit 15 uniquely determines the output values “1 chain” and “2 chain” according to the combination of all input values in the truth table. For example, when all input values are 1, the output value “1 chain” is “0” and “2 chain” is “1”. In other cases, the output value “1 chain” is “1”, “2” “Chain” is set to “0”. In this case, the number of RF chains is set to “2” only when the average RSSI is high, the average FER is small, the average throughput is high, and there is a power saving request. In other cases, the number of RF chains is “1”. "Is set. Thus, when necessary, high-speed communication is provided by “2 chains”, and in other cases, a method of reducing power consumption by using “1 chain” is used.

  Thereafter, the state control unit 15 notifies the wireless communication control unit 11 of the selected number of RF chains and the transmission rate table corresponding to the number of chains as in the first embodiment. Then, the wireless communication control unit 11 performs transmission rate selection processing as in the first embodiment.

  As described above, according to the present embodiment, the state control unit 15 can set the number of RF chains by an arbitrary combination of rules by the administrator of the radio base station 1. Alternatively, the state control unit 15 can set the number of RF chains by using an input / output value of an arbitrary truth table by the administrator of the radio base station 1. As a result, the administrator of the radio base station 1 can automatically reduce power consumption according to the radio communication environment and communication usage status by using simple instructions such as rules and truth tables. The radio base station can be configured so that high-speed communication can be provided instantaneously.

  And, as with the wireless base station 1 described above, a method for estimating the power consumption efficiency for each transmission rate and enabling selection of a highly efficient transmission rate, along with changes in wireless communication status or wireless usage status, By automatically selecting the radio communication circuit (number of RF chains) to be used, the power consumption of the radio base station is reduced without impairing convenience.

  The wireless base station described above can be used as, for example, a wireless base station (AP) in a wireless LAN standard represented by IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11j, IEEE 802.11n. . In addition, base stations (BS, Node B) in wireless communication of high-speed data communication networks (3G, LTE, WiMAX) represented by mobile phone networks, and wireless LAN standards (IEEE 802.11ac, IEEE 802.11ah) to be realized in the near future ) And data communication standards (IEEE 1900.6) for spectrum sensing, and other general-purpose data networks that can also be used as data transfer devices (parent devices) such as routers and LAN switches. it can.

<Appendix>
Part or all of the above-described embodiment can be described as in the following supplementary notes. The outline of the configuration of the wireless communication apparatus (see FIG. 15), the program, and the wireless communication method according to the present invention will be described below. However, the present invention is not limited to the following configuration.

(Appendix 1)
A wireless communication control unit 101 that controls the operation of transmitting and receiving signals simultaneously with a plurality of wireless communication circuits in the same frequency band;
A wireless communication monitoring unit 102 that detects characteristics of signals transmitted and received by the wireless communication circuit and stores them in the signal characteristic database 111 as signal characteristic information;
A transmission rate table 112 that stores the number of RF chains representing the number of the wireless communication circuits and the transmission rates that can be used when signals are transmitted and received by the wireless communication circuits of the number of RF chains;
A state control unit 103 that selects the number of RF chains used for signal transmission / reception based on signal characteristic information of transmitted / received signals stored in the signal characteristic database;
The wireless communication control unit 101 acquires the transmission rate associated with the number of RF chains selected by the state control unit from the transmission rate table, and transmits the transmission rate and the number of RF chains for each transmission rate. Calculating an estimated value of power consumption when a signal is transmitted / received by a calculation formula set in advance, and selecting a transmission rate for transmitting / receiving a signal based on the estimated value,
Wireless communication device 100.

(Appendix 2)
The wireless communication device according to attachment 1, wherein
The state control unit is used for signal transmission / reception based on a statistical value of signal characteristic information for each characteristic of a signal transmitted / received in a predetermined unit time among signal characteristic information stored in the signal characteristic database. Select the number of RF chains,
Wireless communication device.

(Appendix 3)
The wireless communication device according to attachment 2, wherein
The state control unit is used for signal transmission / reception based on an average value of signal characteristic information for each characteristic of a signal transmitted / received in a predetermined unit time among signal characteristic information stored in the signal characteristic database. Select the number of RF chains,
Wireless communication device.

(Appendix 4)
The wireless communication device according to appendix 2 or 3,
The state control unit selects the number of RF chains to be used for signal transmission and reception based on a statistical value of signal characteristic information in one preset characteristic.
Wireless communication device.

(Appendix 5)
The wireless communication device according to appendix 2 or 3,
The state control unit determines a truth value for each characteristic based on a statistical value of signal characteristic information for each of a plurality of preset characteristics, and sets a predetermined logical expression for the truth value for each of the plurality of characteristics. Based on the number of RF chains used for signal transmission / reception,
Wireless communication device.

(Appendix 6)
The wireless communication device according to attachment 5, wherein
The state control unit determines a truth value of the state based on state information representing the state of the wireless communication device, and sets a logical value set in advance for the truth value of the state and the truth value for each characteristic of the signal. Based on the number of RF chains used for signal transmission / reception,
Wireless communication device.

(Appendix 7)
The wireless communication device according to any one of appendices 2 to 6,
The state control unit selects the number of RF chains used for signal transmission / reception every time a predetermined time elapses.
Wireless communication device.

(Appendix 8)
The wireless communication device according to any one of appendices 1 to 7,
The wireless communication monitoring unit detects at least one characteristic among the information indicating the reception intensity of the signal, the number of frames, the transmission rate, and whether or not the transmission / reception of the signal is successful, as the characteristic of the transmitted / received signal,
Wireless communication device.

(Appendix 9)
Wireless communication device
A wireless communication control unit that controls the operation of transmitting and receiving signals simultaneously with a plurality of wireless communication circuits in the same frequency band;
A wireless communication monitoring unit that detects characteristics of signals transmitted and received by the wireless communication circuit and stores them in a signal characteristic database as signal characteristic information;
A state control unit that selects the number of RF chains used for signal transmission and reception based on signal characteristic information of transmitted and received signals stored in the signal characteristic database;
And realize
The wireless communication control unit stores the transmission stored in association with the number of RF chains representing the number of the wireless communication circuits and the transmission rate that can be used when signals are transmitted and received by the wireless communication circuits of the number of RF chains. The power consumption when acquiring the transmission rate associated with the number of RF chains selected by the state control unit from the rate table and transmitting / receiving signals at the transmission rate and the number of RF chains for each transmission rate The estimated value of is calculated by a preset calculation formula, and a transmission rate for transmitting and receiving signals is selected based on the estimated value.
A program to make things happen.

(Appendix 9-2)
The program according to appendix 9, wherein
The state control unit is used for signal transmission / reception based on a statistical value of signal characteristic information for each characteristic of a signal transmitted / received in a predetermined unit time among signal characteristic information stored in the signal characteristic database. Select the number of RF chains,
program.

(Appendix 10)
In a wireless communication device including a wireless communication control unit that controls the operation of transmitting and receiving signals simultaneously with a plurality of wireless communication circuits in the same frequency band,
Detect the characteristics of the signal transmitted and received by the wireless communication circuit, store it in the signal characteristics database as signal characteristics information,
Based on the signal characteristic information of the transmitted and received signals stored in the signal characteristic database, select the number of RF chains used for signal transmission and reception,
The number of RF chains representing the number of the wireless communication circuits and the transmission rate that can be used when signals are transmitted / received by the wireless communication circuits of the number of RF chains are selected from the transmission rate table stored in association with each other. The transmission rate associated with the number of RF chains obtained is obtained, and an estimated value of power consumption efficiency when a signal is transmitted and received at the transmission rate and the number of RF chains for each transmission rate is calculated using a preset calculation formula And selecting a transmission rate for transmitting and receiving signals based on the estimated value.
Wireless communication method.

(Appendix 10-2)
The wireless communication method according to appendix 10, wherein
The number of RF chains used for signal transmission / reception is selected based on a statistical value of signal characteristic information for each characteristic of a signal transmitted / received in a predetermined unit time among signal characteristic information stored in the signal characteristic database. ,
Wireless communication method.

  Note that the above-described program is stored in a storage device or recorded on a computer-readable recording medium. For example, the recording medium is a portable medium such as a flexible disk, an optical disk, a magneto-optical disk, and a semiconductor memory.

  Although the present invention has been described with reference to the above-described embodiment and the like, the present invention is not limited to the above-described embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

1 wireless base station 2 wireless terminal 11 wireless communication control unit 12 RF chain 13 other communication control unit 14 wireless communication monitoring unit 15 state control unit 16 power consumption estimation model calculation unit 17 statistical processing unit 20 DB

Claims (10)

A wireless communication control unit that controls the operation of transmitting and receiving signals simultaneously with a plurality of wireless communication circuits in the same frequency band;
A wireless communication monitoring unit that detects characteristics of signals transmitted and received by the wireless communication circuit and stores them in a signal characteristic database as signal characteristic information;
A transmission rate table in which the number of RF chains representing the number of the wireless communication circuits and the transmission rates that can be used when transmitting and receiving signals with the wireless communication circuits of the number of RF chains are stored in association with each other;
A state control unit that selects the number of RF chains used for signal transmission and reception based on signal characteristic information of transmitted and received signals stored in the signal characteristic database;
The wireless communication control unit acquires the transmission rate associated with the number of RF chains selected by the state control unit from the transmission rate table, and uses the transmission rate and the number of RF chains for each transmission rate. Calculate an estimated value of power consumption efficiency when a signal is transmitted and received by a preset calculation formula, and select a transmission rate for transmitting and receiving the signal based on the estimated value.
Wireless communication device. The wireless communication device according to claim 1,
The state control unit is used for signal transmission / reception based on a statistical value of signal characteristic information for each characteristic of a signal transmitted / received in a predetermined unit time among signal characteristic information stored in the signal characteristic database. Select the number of RF chains,
Wireless communication device. The wireless communication device according to claim 2,
The state control unit is used for signal transmission / reception based on an average value of signal characteristic information for each characteristic of a signal transmitted / received in a predetermined unit time among signal characteristic information stored in the signal characteristic database. Select the number of RF chains,
Wireless communication device. The wireless communication device according to claim 2 or 3,
The state control unit selects the number of RF chains to be used for signal transmission and reception based on a statistical value of signal characteristic information in one preset characteristic.
Wireless communication device. The wireless communication device according to claim 2 or 3,
The state control unit determines a truth value for each characteristic based on a statistical value of signal characteristic information for each of a plurality of preset characteristics, and sets a predetermined logical expression for the truth value for each of the plurality of characteristics. Based on the number of RF chains used for signal transmission / reception,
Wireless communication device. The wireless communication device according to claim 5,
The state control unit determines a truth value of the state based on state information representing the state of the wireless communication device, and sets a logical value set in advance for the truth value of the state and the truth value for each characteristic of the signal. Based on the number of RF chains used for signal transmission / reception,
Wireless communication device. A wireless communication apparatus according to any one of claims 2 to 6,
The state control unit selects the number of RF chains used for signal transmission / reception every time a predetermined time elapses.
Wireless communication device. A wireless communication apparatus according to any one of claims 1 to 7,
The wireless communication monitoring unit detects at least one characteristic among the information indicating the reception intensity of the signal, the number of frames, the transmission rate, and whether or not the transmission / reception of the signal is successful, as the characteristic of the transmitted / received signal,
Wireless communication device. Wireless communication device
A wireless communication control unit that controls the operation of transmitting and receiving signals simultaneously with a plurality of wireless communication circuits in the same frequency band;
A wireless communication monitoring unit that detects characteristics of signals transmitted and received by the wireless communication circuit and stores them in a signal characteristic database as signal characteristic information;
A state control unit that selects the number of RF chains used for signal transmission and reception based on signal characteristic information of transmitted and received signals stored in the signal characteristic database;
And realize
The wireless communication control unit stores the transmission stored in association with the number of RF chains representing the number of the wireless communication circuits and the transmission rate that can be used when signals are transmitted and received by the wireless communication circuits of the number of RF chains. The power consumption when acquiring the transmission rate associated with the number of RF chains selected by the state control unit from the rate table and transmitting / receiving signals at the transmission rate and the number of RF chains for each transmission rate Calculating an estimated value of efficiency by a preset calculation formula, and selecting a transmission rate for transmitting and receiving signals based on the estimated value;
A program to make things happen. In a wireless communication device including a wireless communication control unit that controls the operation of transmitting and receiving signals simultaneously with a plurality of wireless communication circuits in the same frequency band,
Detect the characteristics of the signal transmitted and received by the wireless communication circuit, store it in the signal characteristics database as signal characteristics information,
Based on the signal characteristic information of the transmitted and received signals stored in the signal characteristic database, select the number of RF chains used for signal transmission and reception,
The number of RF chains representing the number of the wireless communication circuits and the transmission rate that can be used when signals are transmitted / received by the wireless communication circuits of the number of RF chains are selected from the transmission rate table stored in association with each other. The transmission rate associated with the number of RF chains obtained is obtained, and an estimated value of power consumption efficiency when a signal is transmitted and received at the transmission rate and the number of RF chains for each transmission rate is calculated using a preset calculation formula And selecting a transmission rate for transmitting and receiving signals based on the estimated value.
Wireless communication method.

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