JP2010074467A - Radio communication method using preamble having header optimization field - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication method using a physical layer header capable of dynamically adopting modulation/diffusion methods according to a transmission condition and a channel condition. <P>SOLUTION: A radio communication device includes a condition recognition part (13) for recognizing one or both of traffic and the channel conditions, a physical layer header information selection part (15) for selecting a modulation method, an encoding method and a diffusion method in the physical layer header on the basis of the recognized information by the condition recognition part, and a frame preparation part (11) for providing a header optimization field for optimizing the physical layer header in a preamble using the selected information. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication method and apparatus. More specifically, the present invention relates to a wireless communication method and apparatus using a preamble having a header optimization field.

  In a wireless communication system using frames, a header is located between a preamble and a payload. FIG. 1 is a diagram illustrating an example of a frame format. As shown in FIG. 1, the header includes a physical layer (PHY) header and a MAC header. The PHY header is a header including information related to the physical layer. Examples of information included in the PHY header are payload length, modulation scheme, FEC (Forward Error Correction), and the like. These pieces of information are essential information when the receiver demodulates the received data.

  In IEEE 802.11 and IEEE 802.15, the PHY header includes information on parameters related to the physical layer included in the same frame. However, the PHY header does not include information related to PHY, but includes only parameters.

  However, if the physical layer is fixed, the flexibility of the system decreases. For example, when the channel condition is good, the data rate can be increased by modulating the payload in a high order. However, when a header indicating a low data rate is used, transmission cannot be made efficient. On the other hand, when the channel condition deteriorates, various measures are required for the header in order to reduce the possibility of packet loss.

  On the other hand, the preamble has been used only for synchronizing and notifying the start of a signal. FIG. 2 is a diagram showing a configuration of a PCLP (Physical Layer Convergence Protocol) preamble defined in IEEE 802.11b. As shown in FIG. 2, the PCLP preamble has a short preamble 5 used for timing detection and long preambles 7a and 7b mainly used for AFC (automatic frequency control). The short preamble 5 includes 10 short training symbols. Each short training symbol is a fixed pattern signal with a period of 0.8 microseconds. On the other hand, the long preamble includes a guard interval of 1.6 microseconds and two long training symbols. Each long training symbol is a fixed pattern signal with a period of 3.2 microseconds. Thus, for example, in IEEE 802.11b, the PCLP preamble is a fixed waveform signal of 16 microseconds.

However, Japanese Patent Laying-Open No. 2005-311532 discloses “a wireless communication method capable of adding arbitrary data to a preamble signal used in the physical layer” (paragraph [0001]). The wireless communication method disclosed in this publication is “transferring arbitrary data together with a flag signal that informs that there is a signal in Qch using a Qch data area that is not used when transmitting a preamble signal” ( wrap up).
JP-A-2005-311532

  It is an object of the present invention to provide a wireless communication method using a physical layer header that can dynamically adopt a modulation / code / spreading method in accordance with transmission conditions and channel conditions. An object of the present invention is to provide a wireless communication method capable of improving throughput and flexibility.

  The present invention is basically based on the knowledge that a header can be dynamically controlled by providing a header optimization field in a preamble. The preamble is located immediately before the header. For this reason, by providing a header optimization field based on the transmission status and channel condition in the preamble, it is possible to dynamically reflect the status such as an optimal modulation / code / spreading scheme. In addition, when the parameters included in the physical layer header are the same as those immediately before, by including a flag indicating that in the preamble, the work of rereading the physical layer header can be reduced.

  A first aspect of the present invention relates to a wireless communication method using a frame. The frame includes a preamble, a header, and a payload. The method includes the step of providing a header with a header optimization field for optimizing the header.

  The “header optimization field” is preferably a field for optimizing the header of the same frame as the preamble. The “header optimization field” includes information on at least one of a modulation scheme, a coding scheme, and a spreading scheme in the header.

  The header usually includes a physical layer header. A preferable “header optimization field” includes a flag indicating whether or not the parameter in the physical layer header is the same as the parameter in the physical layer header included in the immediately preceding frame.

  The second aspect of the present invention relates to a wireless communication apparatus. This wireless communication apparatus is particularly effective as a short-range wireless communication terminal. The wireless communication apparatus includes a frame creation unit 11, a situation grasping unit 13, and a physical layer header information selection unit 15. Thereby, the wireless communication method described above can be realized.

  The frame creation unit 11 is a part for creating a frame. The frame creation unit 11 uses at least one information among the modulation method, coding method, and spreading method in the physical layer header selected by the physical layer header information selection unit to convert the physical layer into a preamble included in the frame. A header optimization field is provided for optimizing the header.

  The situation grasping unit 13 is a part that grasps either or both of traffic and channel condition. The physical layer header information selection unit 15 selects at least one of a modulation scheme, a coding scheme, and a spreading scheme in the physical layer header based on either or both of traffic and channel condition grasped by the situation grasping section. It is a part to do.

  By providing a header optimization field based on the transmission status and channel condition in the preamble, traffic and channel conditions can be dynamically reflected, such as an optimal modulation / code / spreading method. In addition, when the parameters included in the physical layer header are the same as those immediately before, by including a flag indicating that in the preamble, the work of rereading the physical layer header can be reduced. Thereby, the throughput and flexibility of the wireless communication system can be improved.

  FIG. 3 is a block diagram for explaining the wireless communication apparatus of the present invention. As shown in FIG. 3, the wireless communication device 10 of the present invention includes a frame creation unit 11, a situation grasping unit 13, and a physical layer header information selection unit 15.

  The wireless communication device 10 is a device (DEV, PNC) used for short-range wireless communication. These devices are devices used in a wireless network.

  FIG. 4 is a schematic diagram illustrating an IEEE 802.15.3 wireless network. In this example, the network 100 includes client apparatuses 102a, 102b, and 102c, which are three communication terminals, and a central coordination apparatus 104 called a piconet controller (PNC). All devices preferably share the same frequency band for signal transmission in the network 100. The PNC 104 broadcasts a beacon 108 positioned at the head of each super frame to all client devices in the network. Since the beacon includes information on when and how to access the medium, all client terminals can decode (decode) the beacon signal. Data communication can occur between links 106 having the same signal format as well as via a link 110 via PNC.

  Some wireless PAN networks transmit and receive data between terminals constituting the network. In such a wireless PAN, terminals that make up a network perform data transmission and reception ad hoc via-to-via.

  The frame creation unit 11 is a part for creating a frame used for communication. A frame includes a preamble, a header, and a payload. As shown in FIG. 1, the header includes a physical layer header (PLCP header). Moreover, a so-called super frame is a preferred frame in the present invention. Superframes are used in short-range wireless communication. A superframe is a period that is cycled by a beacon.

  FIG. 5 is a diagram illustrating an example of a superframe format. In the superframe shown in FIG. 5, the first time segment is called beacon time. In the beacon time, the start of the piconet is indicated, and time allocation and management information are transmitted by the PNC (piconet coordinator). The next time is called the contention access period (CAP). In CAP, CSMA / CA is performed through backoff. Also, asynchronous data and information exchange not related to time are performed using CAP. The last divided period is a channel time allocation time (CTAP). CTAP is used for TDMA type communication. In CTAP, PNC assigns several channel time allocations (CTA) for some devices and can send data without contention.

  Note that CTA may be replaced with MCTA. In MCTA (Management CTA), a channel can be accessed using Slotted Aloha. In the example shown in FIG. 5, MCTA1 and MCTA2 are provided. A guard time is provided in front of them. In the second half of the CTAP period, guard time, CTA1, guard time, and CTA2 are provided in this order.

  The frame creation unit 11 uses at least one information among the modulation method, coding method, and spreading method in the physical layer header selected by the physical layer header information selection unit to convert the physical layer into a preamble included in the frame. This is a part for providing a header optimization field for optimizing the header.

  FIG. 6 is a diagram for explaining an example of a frame created by the frame creation unit 11. As shown in FIG. 6, the frame 111 in the present invention includes, for example, a preamble 113, a header 115, and a payload 117. The preamble 113 has a header optimization field 119. The field position of the header optimization field may be provided at any position as long as it is ahead of the header.

  The situation grasping unit 13 is a part that grasps either or both of traffic and channel condition. Traffic and channel conditions may be ascertained using known methods. That is, in wireless communication, the parameters of the physical layer header are changed according to normal traffic and channel conditions. Therefore, traffic and channel conditions may be ascertained in the same manner as in normal wireless communication. In normal wireless communication, parameters included in the physical layer header are changed. On the other hand, in the present invention, for example, the modulation method, coding method, spreading method, etc. of the physical layer header are dynamically changed according to traffic and channel conditions.

  The physical layer header information selection unit 15 selects at least one of a modulation scheme, a coding scheme, and a spreading scheme in the physical layer header based on either or both of traffic and channel condition grasped by the situation grasping section. It is a part to do. The information recording unit 41 stores parameters included in the physical header in the immediately preceding frame. If the physical layer header information selection unit 15 recognizes that the same parameter as that included in the immediately preceding physical header is used, a flag indicating that may be provided in the preamble. The communication terminal that has analyzed the preamble can reduce the work of rereading the physical layer header. Thereby, the throughput and flexibility of the wireless communication system can be improved.

  Next, the elements of the communication apparatus of the present invention will be described with reference to FIG. This communication terminal 10 has an antenna 21, receives a signal transmitted from a peripheral communication terminal through the antenna 21, and transmits a transmission signal from the own terminal. The antenna 21 is connected to the wireless reception unit 23 and the wireless transmission unit 25. For example, the wireless transmission unit 25 performs modulation processing as an ultra-wide band (UWB) signal. On the other hand, the radio receiver 23 performs, for example, UWB signal demodulation processing. Then, the wireless receiving unit 23 supplies the demodulated signal to another circuit. In addition to UWB modulation, a known modulation method can be used.

  The wireless reception unit 23 supplies the demodulated signal to the reception data analysis unit 27. Then, the reception data analysis unit 27 extracts a data information part constructed in a predetermined format from the received signal.

  Particularly in the present invention, the received data analysis unit 27 also analyzes the header optimization field in the preamble. The header optimization field includes information on at least one of a modulation scheme, a coding scheme, and a spreading scheme in the physical layer header. Therefore, the physical layer header is analyzed based on the information included in the header optimization field. For example, when the header optimization field includes information indicating the modulation method A, the physical layer header included in the same frame is handled as a signal modulated by the modulation method A. That is, a signal that modulates the physical layer header is output by a method of demodulating a signal modulated by the modulation method A, and stored in the memory. When the physical layer header is analyzed, the information stored in the memory is used to analyze the physical layer header by the demodulation method.

  Examples of modulation schemes include OFDM (frequency division division), ASK (amplitude shift keying), PSK (phase shift keying), FSK (frequency shift keying), QAM (direct amplitude modulation), and the like.

  Examples of coding schemes include cyclic redundancy verification (CRC) code, STC (time-space coding), and the like.

  Examples of the spreading method include direct spreading and frequency hopping spread spectrum method (FHSS). An example of direct diffusion is DSSS (Direct Sequence Spread Spectrum). In wireless LAN IEEE 802.11b, DS-SS is adopted as a spreading method. As a diffusion method, there is a hybrid method in which FHSS and DSSS are mixed.

  The communication terminal includes a reference time generation unit 35 that generates a clock signal serving as a reference for the operation time at a predetermined interval. The clock signal generated by the reference time generation unit 35 is supplied to each unit such as the central control unit 31. Further, the communication terminal has a timing control unit 33 that sets various timings based on the control of the central control unit 31.

  The wireless transmission unit 25 modulates the transmission information generated by the transmission data generation unit 37 and the application data information supplied from the data buffer 39 into a predetermined signal format. The central control unit 31 is connected to the information recording unit 41. The information recording unit 41 is configured by a memory. And the information recording part 41 has memorize | stored the control program, for example. The central control unit 31 reads the control program and performs various arithmetic processes based on the control program command.

  In the present invention, it is preferable that the information recording unit 41 has a modulation system, a coding system, and a spreading system recorded in a database according to traffic and channel conditions. Then, using the information such as traffic and channel condition input via the interface 43, the situation grasping unit 13 grasps the situation. Then, the physical layer header information selection unit 15 can read out an appropriate modulation method, encoding method, and spreading method from the information recording unit 41 using the information regarding the grasped situation. Then, information on the modulation method, coding method, and spreading method is transmitted to the transmission data generation unit 37, and when the frame creation unit 11 creates a frame, a header optimization field for optimizing the header is used as the header. Can be provided.

  Next, a wireless communication method according to the present invention will be described. This wireless communication method can be performed using an up-to-date wireless communication device.

  As described above, the wireless communication method of the present invention includes a step of providing a header with a header optimization field for optimizing the header.

  The “header optimization field” is preferably a field for optimizing the header included in the same frame as the preamble. The “header optimization field” includes information on at least one of a modulation scheme, a coding scheme, and a spreading scheme in the header.

  Since the preamble includes a header optimization field for optimizing the header, the modulation method, coding method, and spreading method in the physical layer header are dynamically changed according to traffic and channel conditions. be able to.

  A preferred “header optimization field” includes a flag indicating whether the parameter in the physical layer header is the same as the parameter in the physical layer header included in the immediately preceding frame. That is, when the preamble includes a flag that is the same as the parameter in the physical layer header included in the immediately preceding frame, it is not necessary to analyze the physical layer header. This flag may be a flag indicating whether the modulation scheme, the encoding scheme, and the spreading scheme are the same. In this case, the physical layer header can be analyzed in the same manner as when the previous frame is demodulated.

  The present invention can be used in the field of wireless communication.

FIG. 1 is a diagram illustrating an example of a frame format. FIG. 2 is a diagram illustrating the configuration of the PCLP preamble. FIG. 3 is a block diagram for explaining the wireless communication apparatus of the present invention. FIG. 4 is a schematic diagram illustrating a wireless network. FIG. 5 is a diagram illustrating an example of a superframe format. FIG. 6 is a diagram for explaining an example of a frame created by the frame creation unit.

Explanation of symbols

5 Short Preamble 7a, 7b Long Preamble 10 Wireless Communication Device (Communication Terminal)
11 Frame creation unit 13 Situation grasping unit 15 Physical layer header information selection unit 21 Antenna 23 Radio reception unit 25 Radio transmission unit 27 Reception data analysis unit 31 Central control unit 33 Timing control unit 35 Reference time generation unit 37 Transmission data generation unit 39 Data Buffer 41 Information recording unit 43 Interface 100 Network 102a, 102b, 102c Client device 104 Central coordination device (PNC)
106 link 108 beacon 110 link via PNC

Claims (4)

A wireless communication method using a frame including a preamble, a header, and a payload,

In the preamble,
Providing a header optimization field for optimizing the header,

Wireless communication method.
The header optimization field is:
A field for optimizing the header of the same frame as the preamble;
Information on at least one of a modulation scheme, a coding scheme, and a spreading scheme in the header is included;

The wireless communication method according to claim 1.
The header includes a physical layer header;

The header optimization field is:
And a flag indicating whether the parameter in the physical layer header is the same as the parameter in the physical layer header included in the immediately preceding frame,

The wireless communication method according to claim 1. A frame creation unit (11) for creating a frame, wherein the frame includes a preamble, a header including a physical layer header, and a payload;
A situation grasping unit (13) for grasping one or both of traffic and channel condition;
A physical layer header information selection unit that selects at least one of a modulation method, a coding method, and a spreading method in the physical layer header based on either or both of the traffic and channel condition grasped by the situation grasping unit ( 15) and
Including

The frame creation unit (11)
Using at least one information among a modulation method, a coding method, and a spreading method in the physical layer header selected by the physical layer header information selection unit,
A header optimization field for optimizing the physical layer header is provided in a preamble included in the frame.

Wireless communication device.

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