JP2014017706A - Radio communication device and program, and communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently secure stable communication and reduce power consumption in a radio communication device of an ad hoc network in which channel allocation to each radio communication device is performed on a time slot basis and a packet destination excluding a broadcast packet is identified on the time slot basis.SOLUTION: The radio communication device includes: a MAC unit 11 for storing schedule information including a processing type for each time slot and transmission power control information, and for reading out the stored transmission power control information at a time slot when the processing type is transmission processing, to perform transmission power control; and a PHY unit 12 for setting, as the transmission power control information to be stored, information to be transmission power to a broadcast packet, and setting information to be transmission power according to a communication state with the radio communication device of an identified transmission destination to another packet.

Description

  The present invention relates to a wireless communication apparatus, a program, and a communication control method for performing transmission power control.

  In a wireless communication system of an ad hoc network that forms a network without going through a base station, wireless communication devices directly exchange packets. As a wireless communication system using such a protocol, there are a wireless LAN ad hoc mode and an MB-OFDM UWB (Ultra Wide Band) communication. In particular, UWB communication uses a super frame as a basic timing structure for packet exchange, and the super frame is further divided into time slot units.

  Each superframe starts from a beacon period in which a plurality of beacon slots obtained by further dividing time slots, and each wireless communication apparatus transmits a broadcast beacon packet using one of the different beacon slots during this period. Thereby, each wireless communication apparatus shares information regarding the network, and performs synchronization and management with the network.

  Each wireless communication device uses a period other than the beacon period in the superframe as a data period for transmitting and receiving packets between the wireless communication devices. As an access control method at that time, it corresponds to a distributed reservation protocol in which each wireless communication apparatus performs channel reservation in units of time slots. In wireless communication using this distributed reservation protocol, a wireless communication device that is a destination of packet transmission is specified when a time slot is reserved. Therefore, the transmission destination of packets excluding beacon packets is specified in units of time slots.

  By the way, in the wireless communication device, it is necessary to ensure stable communication and reduce power consumption. Therefore, a technique for controlling transmission power according to the communication status with the communication partner due to the communication distance, noise, presence or absence of obstacles, etc. has been devised, and it is also used in a wireless communication system composed of a plurality of wireless communication devices. It is already known that

  Patent Document 1 discloses an object of maintaining normal communication quality of the entire network by avoiding packet loss due to insufficient transmission power while performing transmission power control in an ad hoc network to reduce power consumption of a wireless communication device. Thus, a configuration is disclosed in which each wireless communication device performs transmission power control to perform transmission or performs transmission with maximum transmission power in accordance with the packet destination and the packet to be transmitted.

  However, transmission power control in a conventional wireless communication system is based on communication via a base station in a wide area, and there are no base stations in an ad hoc network wireless communication system. There has been a problem that the transmission power control of the communication apparatus cannot be centrally managed.

  Further, the technique disclosed in Patent Document 1 assigns a channel to each wireless communication device in units of time slots, and a wireless communication system of an ad hoc network in which destinations of packets other than broadcast packets are specified in units of time slots. However, there is a problem that it is difficult to ensure stable communication and reduce power consumption.

  The present invention is for solving the above-described problems, and an object of the present invention is to assign a channel to each wireless communication device in units of time slots, and a transmission destination of packets excluding broadcast packets is in units of time slots. In the wireless communication device of the specified ad hoc network, it is to more efficiently secure stable communication and reduce power consumption.

  In order to achieve this object, the present invention has the following features.

  A radio communication device according to the present invention is an ad hoc network radio communication device that assigns a channel to each radio communication device in units of time slots, and specifies a transmission destination of packets excluding broadcast packets in units of time slots, Schedule management that stores processing information for each time slot and schedule information including transmission power control information, and reads the stored transmission power control information and performs transmission power control when the processing type is a time slot for transmission processing. The transmission power control information to be stored is information that becomes transmission power for the broadcast packet, and transmission power that corresponds to the communication status with the destination wireless communication device specified for the other packet. Transmission power control information setting means for setting information. To.

  According to the present invention, stable communication is ensured in a radio communication device of an ad hoc network in which a channel is assigned to each radio communication device in units of time slots, and a transmission destination of packets excluding broadcast packets is specified in units of time slots. And power consumption can be reduced more efficiently.

It is a figure which shows the structure of the radio | wireless communications system which concerns on this embodiment. It is a figure which shows the structure of the super-frame which concerns on this embodiment. It is a block diagram which shows the structure of the radio | wireless communication apparatus which concerns on this embodiment. It is a figure which shows the format of the packet handled by the MAC part which concerns on this embodiment. It is a figure which shows the super frame in the radio | wireless communications system which concerns on this embodiment. It is a figure which shows the mode of communication of the radio | wireless communications system in the case of the super frame of FIG. It is a figure which shows the schedule information in the case of the super frame of FIG. It is a transmission processing flow figure in the time slot which performs packet transmission. It is a setting processing flow figure of the transmission power control information in the setting of schedule information. It is a sequence diagram of transmission power control information calculation using the channel reservation procedure of a time slot.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to the present embodiment. FIG. 2 is a diagram illustrating a configuration of a super frame according to the present embodiment.

  The wireless communication system includes three or more wireless communication devices 1, 2, and 3 as its components, and performs direct communication between wireless communication devices without using a base station that is a centralized management mechanism for communication control. Form. Therefore, each wireless communication apparatus performs communication control for the network.

  This communication control is performed in units of time slots obtained by dividing the superframe as shown in FIG. Each superframe begins with a beacon period consisting of one or more consecutive time slots, and each wireless communication device transmits and receives broadcast beacon packets using one of the different time slots during this period. Thereby, each wireless communication apparatus shares information regarding the network, and performs synchronization and management with the network.

  Each wireless communication device uses a period other than the beacon period in the superframe as a data period for transmitting and receiving packets between the wireless communication devices. As an access control method at that time, a distributed reservation protocol is used in which each wireless communication apparatus performs channel reservation in units of time slots. In wireless communication using this distributed reservation protocol, a wireless communication device that is a destination of packet transmission is specified when a time slot is reserved. Therefore, the transmission destination of packets excluding beacon packets is specified in units of time slots.

  Here, the time slot channel reservation will be further described. This reservation procedure is performed through a beacon packet. When a wireless communication device that wants to transmit a packet in a time slot to reserve transmits a beacon packet that includes reservation information for making a reservation request to the wireless communication device that is the destination of packet transmission, packet transmission is performed among the wireless communication devices that have received the beacon packet. The wireless communication device that is the destination of the transmission transmits a beacon packet including reservation information that makes a reservation response based on result information for the reservation.

  Then, when the wireless communication apparatus that has transmitted the beacon packet including the reservation information for performing the reservation request receives the beacon packet including the reservation information for performing the reservation response, the channel reservation for the time slot is established.

  FIG. 3 is a block diagram illustrating a configuration of the wireless communication apparatus according to the present embodiment. The wireless communication device 1 includes a MAC unit 11, a PHY unit 12, and an antenna 13.

  The MAC unit 11 controls the PHY unit 12 to perform communication control as described above, that is, packet transmission / reception control. Therefore, schedule management for each time slot is performed based on schedule information determined through information on timers and beacon packets.

  The schedule information for each time slot includes a processing type and transmission power control information. The processing type represents a combination of a packet type (beacon packet or other data packet) and processing content (transmission processing or reception processing). The transmission power control information is information for controlling the transmission power of the packet output from the PHY unit 12, and designates the transmission power.

  Information for maximum transmission power is set for broadcast packets, and information for transmission power according to the communication status with the destination wireless communication apparatus is set for other packets. Broadcast packets can be delivered to other wireless communication devices as much as possible as the wireless communication device.

  At that time, using the channel reservation procedure of the time slot via the beacon packet, the received signal quality information indicating the communication status with the wireless communication apparatus of the transmission destination is calculated via the PHY unit 12 and transmitted using it. The power control information is further calculated and set in the transmission power control information. Efficient transmission power control can be performed by using broadcast packet exchange for the channel reservation procedure. Here, as the received signal quality information, the received signal strength, the SN ratio, and the like can be considered.

  The calculation of the transmission power control information using the received signal quality information is based on the received signal quality information for the packet transmitted with the maximum transmission power, and a level for reducing the transmission power is obtained, and the transmission power corresponding to the level is calculated. It can be considered to be information that becomes.

  Calculation of transmission power control information using details of schedule information and transmission processing control flow using transmission power control information in a time slot for packet transmission, transmission power control information setting processing flow, and time slot channel reservation procedure The sequence will be described later.

  The PHY unit 12 performs modulation based on the packet transmitted from the MAC unit 11 when transmitting a packet in accordance with an instruction from the MAC unit 11, converts the digital signal into an analog signal, and further performs frequency up-conversion. The received signal is sent to the antenna unit 13. At this time, the intensity of the radio wave to be transmitted is controlled based on the designation from the MAC unit 11. When receiving a packet, the frequency of the analog signal received from the antenna 13 is down-converted, then converted from an analog signal to a digital signal, further demodulated, and passed to the MAC unit 11.

  4A and 4B are diagrams illustrating a format of a packet handled by the MAC unit according to the present embodiment. FIG. 4A is a packet format, and FIG. 4B is a format including special information when the packet is a beacon packet.

  The packet includes transmission source wireless communication device identification information that identifies a wireless communication device that transmits the packet, transmission destination wireless communication device identification information that identifies a wireless communication device that is a transmission destination of the packet, and a certain time slot. It is assumed that the packet includes final packet information indicating whether or not the packet is the final packet. However, in the case of a beacon packet, the transmission destination wireless communication device identification information is information that does not specify a wireless communication device.

  The beacon packet further includes special information. When a channel reservation for a time slot is performed or established, a wireless communication device that exchanges data packets in the time slot includes the reservation information in the beacon packet. . Reservation information includes time slot information, reservation request / response information, and packet transmission destination / source information. Further, when the reservation request / response information is a reservation response, reservation status information, and It shall contain received signal quality information.

  Here, the time slot information is information for identifying a time slot to be reserved, and is, for example, a time slot number.

  The reservation request / response information is a reservation request when the reservation information makes a reservation request, or a reservation response when making a reservation response to the reservation request.

  The packet transmission destination / transmission source information is identification information of the packet transmission destination wireless communication device when the reservation request / response information is a reservation request, and identification information of the packet transmission source wireless communication device when the reservation request / response information is a reservation response. Therefore, a wireless communication apparatus that performs channel reservation for the time slot indicated by the time slot information and transmits a packet in the time slot has a reservation request as the reservation request / response information, and a packet transmission destination as the packet transmission destination / transmission source information. A beacon packet including reservation information consisting of identification information of the wireless communication device is transmitted. The reservation status information is information indicating the result of the reservation request.

  The received signal quality information is received signal quality information calculated by the MAC unit 11 for the beacon packet for which the reservation request has been made. Therefore, reservation status information and received signal quality information are included as reservation information only in the case of reservation information reservation information.

  Therefore, the wireless communication apparatus that has received the beacon packet designated as the packet transmission destination information of the reservation request transmits the reservation response as the reservation request / response information and the reservation request as the packet transmission destination / transmission source information. A beacon packet including reservation information consisting of the identification information, information indicating reservation establishment as reservation status information, and information calculated as reception signal quality information for the received beacon packet as reception signal quality information is transmitted.

  According to this embodiment, each wireless communication device that performs channel assignment to each wireless communication device in units of time slots and forms an ad hoc network in which the transmission destination of packets other than broadcast packets is specified in units of time slots Transmission power control information is stored for each slot, and transmission power is controlled for each time slot based on the stored transmission power control information. Transmission power control information depends on the communication status with the communication partner for information that becomes transmission power for time slots that transmit broadcast packets such as beacon packets, and for time slots that transmit other packets. The information is used as transmission power.

  Therefore, the situation where broadcast packets such as beacon packets do not reach new wireless communication devices participating in the network due to excessively low transmission power is prevented, and transmission with excessively high transmission power is performed for other packets. It is possible to reduce power consumption due to the absence.

  Further, when transmitting a plurality of packets within the same time slot, it is only necessary to perform the transmission power control process once within the time slot, and the process can be simplified. In a wireless communication device of an ad hoc network in which the destination of packets other than broadcast packets is specified in units of time slots, stable communication can be ensured and power consumption can be more efficiently performed. .

  Hereinafter, as a more specific example, description will be made assuming a situation where channel assignment is performed in the superframe shown in FIG. 5 in the wireless communication system of FIG.

  FIG. 5 is a diagram showing a super frame in the wireless communication system according to the present embodiment. FIG. 6 is a diagram showing a state of communication of the wireless communication system in the case of the superframe of FIG. 5, where (a) is time slot 1, (b) is time slot 2, and (c) is time slot 5 and time. Slots 6 and (d) are time slots 7.

  In the case of FIG. 5, the wireless communication device 1 uses the time slot 1, the wireless communication device 2 uses the time slot 2, and the wireless communication device 3 uses the time slot 3 to transmit the beacon packet to the wireless communication device of the entire wireless communication system. Against. Then, as a result of performing channel reservation for the time slot through these beacon packets, the wireless communication device 1 transmits a data packet to the wireless communication device 2 using the time slot 5 and the time slot 6, and uses the time slot 7. The wireless communication device 1 transmits a data packet to the wireless communication device 3, and the wireless communication device 2 transmits a data packet to the wireless communication device 3 using the time slot 9.

  FIG. 6 shows a state of communication in the wireless communication system in the case of time slot 1, time slot 2, time slot 5, time slot 6, and time slot 7 in the superframe of FIG. Next, transmission power control information in each time slot will be described together with schedule information.

  FIG. 7 is a diagram illustrating schedule information in the case of the superframe of FIG. 5, (a) is schedule information in the wireless communication device 1, and (b) is schedule information in the wireless communication device 2.

  In the case of FIG. 5, as schedule information in the MAC unit 11 of the wireless communication device 1, the processing type is transmission processing of beacon packets and transmission power control information is maximum transmission power by setting transmission power control information for time slot 1. Is stored. Information PDev1High is stored. Similarly, for time slot 2 and time slot 3, since the processing type is beacon packet reception processing and the transmission power control information is reception processing, the initial value 0 is stored as it is.

  Then, for time slot 5 and time slot 6, the processing type is data packet transmission processing, and transmission power control information is information PD Dev1 indicating transmission power corresponding to the communication status between wireless communication device 1 and wireless communication device 2. Dev2 is stored.

  In addition, for time slot 7, the processing type is data packet transmission processing, and transmission power control information is stored as information PD Dev1 → Dev3 indicating transmission power according to the communication status between wireless communication device 1 and wireless communication device 3. The

  On the other hand, as the schedule information in the wireless communication device 2, since the processing type is beacon packet reception processing and the transmission power control information is reception processing for time slot 1 and time slot 3, the initial value 0 is stored as it is. The For time slot 2, the processing type stores beacon packet transmission processing, and transmission power control information stores information PD Dev2High indicating the maximum transmission power.

  For the time slot 5 and the time slot 6, the processing type is data packet reception processing, and the transmission power control information is stored with the initial value 0 as it is. In addition, for the time slot 9, the processing type is data packet transmission processing, and the transmission power control information is stored as information PD Dev2 → Dev3 indicating the transmission power according to the communication status between the wireless communication device 2 and the wireless communication device 3. The

  Next, in the MAC unit 11, when the timer becomes a new time slot, the schedule information is referred to, and the processing type is transmission processing, transmission performed in the time slot using the stored transmission power control information A processing flow will be described.

  FIG. 8 is a flow chart of transmission processing in a time slot for performing packet transmission. The wireless communication device 1 reads the transmission power control information of the corresponding time slot from the schedule information of the MAC unit 11 (step S1).

  The MAC unit 11 sets the transmission power of the PHY unit 12 based on the read transmission power control information (step S2). Here, for example, in the case of time slot 1 in FIG. 5, the wireless communication apparatus 1 reads out PD Dev1High shown in FIG. 7A as the transmission power control information. In the case of time slot 5 and time slot 6, PD Dev1 → Dev2 is read. The PHY unit 12 performs packet transmission through the antenna 13 with the set transmission power (step S3).

  When the MAC unit 11 determines that there is further packet transmission in the time slot based on the last packet information in the packet (step S4, Yes), packet transmission is performed via the PHY unit 12 and the antenna 13 with the transmission power maintained. (Step S3), and this process is repeated until the last packet transmission. When the last packet transmission is completed (No at Step S4), the transmission process is terminated.

  FIG. 9 is a flowchart of setting processing of transmission power control information in setting of schedule information. A setting process flow of transmission power control information stored in the schedule information of the MAC unit 11 of the wireless communication device 1 will be described. Transmission power control information is set when the MAC unit 11 sets schedule information.

  If the processing type is not transmission processing among the schedule information to be set (step S11, No), the processing ends without setting transmission power control information.

  If the processing type is a transmission process (step S11, Yes), it is next determined whether the packet type of the processing type is a beacon packet (step S12). When the packet type is a beacon packet (step S12, Yes), transmission power control information indicating transmission power is set (step S13), and the process ends.

  If the packet type is not a beacon packet (No in step S12), the transmission power control information calculated in the channel reservation procedure for the time slot via the beacon packet is set so that the transmission power corresponds to the communication status with the communication partner. (Step S14), and the process ends.

  According to the present embodiment, it is possible to control the transmission power with high accuracy by grasping the communication status with the wireless communication device that is the destination of the packet transmission of the requested channel reservation from the received signal quality information.

  FIG. 10 is a sequence diagram of transmission power control information calculation using a time slot channel reservation procedure.

  In order for the wireless communication apparatus 1 to perform packet communication with the wireless communication apparatus 2, a time slot channel reservation procedure is performed. At this time, the wireless communication apparatus 1 transmits transmission power control information according to the communication status with the wireless communication apparatus 2. A case where the calculation is performed will be described as an example.

  In the time slot 1 of a certain super frame α, the wireless communication device 1 is time slot information to be reserved as time slot information, a reservation request as reservation request / response information, and identification information for the wireless communication device 2 as packet destination / source information. A beacon packet including reservation information consisting of is transmitted by broadcast (step S21).

  The wireless communication device 2 analyzes the reservation information of the received beacon packet, and calculates reception signal quality information for this beacon packet when it is the target of the reservation request (step S22).

  In the time slot 2 of the super frame α, the wireless communication device 2 broadcasts a beacon packet (step S23). In the time slot 3 of the super frame α, the wireless communication device 3 broadcasts a beacon packet (step S24). In time slot 1 of the next superframe α + 1, wireless communication apparatus 1 transmits a beacon packet by broadcast (step S25).

  In the time slot 2 of the superframe α + 1, the wireless communication apparatus 2 reserves time slot information as time slot information, a reservation response as reservation request / response information, and identification information for the wireless communication apparatus 1 as packet transmission destination / source information. Then, a beacon packet including reservation information including reservation establishment as reservation status information and reception signal quality information calculated in step S22 as reception signal quality information is transmitted by broadcast (step S26).

  When the wireless communication device 1 analyzes the reservation information of the received beacon packet and finds that it is the target of the reservation response, the wireless communication device 1 extracts the received signal quality information from the reservation information and controls transmission power based on it. Information is calculated (step S27). In the time slot 8 of the super frame α + 1, the wireless communication device 3 transmits a beacon packet by broadcast (step S28).

  According to this embodiment, it is possible to notify the communication status with the wireless communication apparatus that has requested channel reservation.

1, 2, 3 Wireless communication device 11 MAC unit 12 PHY unit 13 Antenna

Japanese Patent No. 4700902

Claims (7)

Channel allocation to each wireless communication device in units of time slots, and a wireless communication device of an ad hoc network in which transmission destinations of packets excluding broadcast packets are specified in units of time slots,
Schedule management that stores processing information for each time slot and schedule information including transmission power control information, and reads the stored transmission power control information and performs transmission power control when the processing type is a time slot for transmission processing. Means,
As the transmission power control information to be stored, information that becomes transmission power for the broadcast packet, and information that becomes transmission power according to the communication status with the destination wireless communication device specified for other packets are set. Transmission power control information setting means for
A wireless communication apparatus comprising:   2. The wireless communication apparatus according to claim 1, wherein the transmission power control information setting unit calculates information that becomes transmission power according to the communication status in accordance with a channel reservation procedure for a time slot performed through a broadcast packet.   When the transmission power control information setting means receives the broadcast packet designated by itself as a destination of packet transmission of the channel reservation information in the channel reservation procedure of the time slot performed through the broadcast packet, a reception signal indicating a communication status 3. The wireless communication apparatus according to claim 2, wherein the wireless communication apparatus calculates quality information and transmits the quality information including the information in the broadcast packet transmitted by itself.   The transmission power control information setting means sets the transmission power control information when setting the schedule information, and in the case of setting the schedule information for transmitting a packet other than a broadcast packet, the time slot that is set through the broadcast packet In the channel reservation procedure, when a broadcast packet transmitted from a wireless communication device designated as a destination of packet transmission of channel reservation information is received, transmission power corresponding to the communication status is obtained based on the received signal quality information therein. The wireless communication apparatus according to claim 2, wherein the information is calculated and set as transmission power control information.   5. The wireless communication apparatus according to claim 1, wherein the transmission power control information setting unit uses a maximum transmission power as information serving as the transmission power. 6. A program in a wireless communication device of an ad hoc network that assigns a channel to each wireless communication device in units of time slots and in which a transmission destination of packets excluding broadcast packets is specified in units of time slots,
Stores schedule information including the processing type and transmission power control information for each time slot, reads the stored transmission power control information when the processing type is a time slot for transmission processing, and manages the schedule for performing transmission power control Processing,
Transmission that sets transmission power control information to be stored is information that becomes transmission power for broadcast packets, and information that becomes transmission power according to the communication status with the destination wireless communication device specified for other packets A process for setting power control information;
A program that causes a computer to execute. A communication control method in a wireless communication device of an ad hoc network in which channel assignment to each wireless communication device is performed in units of time slots, and the transmission destination of packets excluding broadcast packets is specified in units of time slots,
Stores schedule information including the processing type and transmission power control information for each time slot, reads the stored transmission power control information when the processing type is a time slot for transmission processing, and manages the schedule for performing transmission power control Steps,
Transmission that sets transmission power control information to be stored is information that becomes transmission power for broadcast packets, and information that becomes transmission power according to the communication status with the destination wireless communication device specified for other packets Setting power control information;
A communication control method for a wireless communication apparatus, comprising:

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