KR100961559B1 - Point-to-point communication method using ofdma - Google Patents

Point-to-point communication method using ofdma Download PDF

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Publication number
KR100961559B1
KR100961559B1 KR1020080087543A KR20080087543A KR100961559B1 KR 100961559 B1 KR100961559 B1 KR 100961559B1 KR 1020080087543 A KR1020080087543 A KR 1020080087543A KR 20080087543 A KR20080087543 A KR 20080087543A KR 100961559 B1 KR100961559 B1 KR 100961559B1
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South Korea
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point
terminal
transmitting
communication
receiving terminal
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KR1020080087543A
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Korean (ko)
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KR20100028696A (en
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김학수
성영철
오영석
유희정
이용훈
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한국과학기술원
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02DCLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THIR OWN ENERGY USE
    • Y02D70/00Techniques for reducing energy consumption in wireless communication networks

Abstract

The present invention relates to a point-to-point communication method based on orthogonal frequency division multiple access, wherein the base station receiving the communication request information from the transmitting terminal senses and determines the position of the receiving terminal to determine the steps of (a) and (a). As a result, when the distance between the transmitting terminal and the receiving terminal is within a predetermined range, (b) generating and transmitting the point-to-point OFDMA information including the subcarrier hopping sequence for the point-to-point communication to the transmitting terminal and the receiving terminal, and transmitting (C) performing point-to-point communication according to the OFDMA information received by the terminal and the receiving terminal.
According to the present invention as described above, by providing a point-to-point communication between the transmitting and receiving terminals in close proximity to each other in the cellular system using the OFDMA transmission scheme, to minimize the time delay and uplink interference through the base station, resource allocation By applying the concept of spatial resource recycling based on a viewpoint, the resource utilization is maximized and the point-to-point communication between the transmitting and receiving terminals can be performed at low power, thereby minimizing the power consumption of the terminal.
Transmitting terminal, base station, receiving terminal, OFDMA, subcarrier, hopping, sequence, point-to-point, channel, sensing, RTS, CTS

Description

Point-to-point communication method based on orthogonal frequency division multiple access {POINT-TO-POINT COMMUNICATION METHOD USING OFDMA}

The present invention relates to a point-to-point communication method based on Orthogonal Frequency Division Mdulation / Multiplexing Access (OFDMA), and more particularly, communication between terminals in a cellular system using an OFDMA transmission scheme. The present invention relates to a point-to-point communication technology based on orthogonal frequency division multiple access that minimizes uplink interference by providing a point-to-point (P2P) communication method capable of forming a link.

In cellular communication, a service area is divided into 'cells', which are small local units, which are areas covered by a base station. The size of the cell may vary depending on the density of the subscriber. In general, as the density of the subscriber increases, the size of the cell decreases.

However, in this cellular method, a link is always formed through a base station for communication between terminals, and even when communication between adjacent terminals, the transmitting terminal always transmits a signal to the base station, and then the base station returns to the receiving terminal. Will be sent.

For example, in a campus and an office environment, in many cases, terminals to communicate with each other exist in one cell, and the distance is often very close. Even in this case, when transmitting its data to the transmitting terminal base station, the base station should receive it and transmit it back to the receiving terminal. That is, since the transmission is made through two links, the channel is used twice.

In addition, when the terminals are located at the edge of the cell, although the receiving terminal is near, there is a disadvantage in that high power must be used in the transmitting terminal to transmit data to the base station.

In addition, while transmitting at a high power is a problem in the battery consumption of the transmitting terminal itself, there is a disadvantage that affects the interference to other cells around the same subcarrier.

Looking at the problem as described above with reference to Figure 1 as follows. When there is a link 1 for transmitting data to the base station and a link 2 for transmitting data from the base station to the receiving terminal at the edge of the cell, the transmitting terminal requires high transmission power to form link 1.

Accordingly, interference such as link 4 occurs, and when the second transmitting terminal requests link 3 communication to the second base station, as a result of the interference, the overall throughput (data transmission throughput) is reduced.

The present invention has been made to solve the above problems, and provides a point-to-point communication between transmitting and receiving terminals in close proximity to a cellular system using an OFDMA transmission scheme, thereby eliminating time delay and uplink interference caused by a base station. The purpose is to provide a point-to-point communication method based on orthogonal frequency division multiple access that maximizes resource utilization by minimizing and applying spatial resource recycling.

Orthogonal frequency division multiple access based point-to-point communication method according to the present invention for achieving the technical problem, (a) the base station receiving the communication request information from the transmitting terminal senses and determines the position of the receiving terminal, As a result of the determination in step (a), when the distance between the transmitting terminal and the receiving terminal is within a preset range, the point-to-point OFDMA information including the subcarrier hopping sequence for the point-to-point communication is generated and transmitted to the transmitting terminal and the receiving terminal ( b) and performing point-to-point communication according to the OFDMA information received by the transmitting terminal and the receiving terminal.

In addition, after step (b), the method further includes the step (c ') of performing point-to-point communication in the CDMA system by interpreting the OFDMA information received by the transmitting terminal and the receiving terminal as a spreading code.

The subcarrier hopping sequence may be determined through channel sensing of an empty subcarrier sequence for a predetermined time in a plurality of OFDM symbol intervals.

In addition, the channel sensing is characterized in that the sensing time and the number of times is adjusted according to the relative distance between the transmitting terminal and the receiving terminal.

In addition, when the distance between the transmitting terminal and the receiving terminal exceeds the preset range as a result of the determination in step (a), transmitting the communication request information to the receiving terminal and transmitting the received communication response information to the transmitting terminal (d). It includes more.

(E) replacing step (a) through step (c) by performing point-to-point communication through RTS / CTS packet exchange between the transmitting terminal and the receiving terminal according to the OFDMA information previously stored in the transmitting terminal and the receiving terminal. Include.

According to the present invention as described above, by providing the point-to-point communication between the transmitting and receiving terminals in close proximity to the cellular system using the OFDMA transmission scheme, there is an effect of minimizing the time delay and uplink interference through the base station.

In addition, by applying the concept of spatial resource recycling based on the resource allocation perspective, there is an effect of maximizing resource utilization.

In addition, since point-to-point communication between the transmitting and receiving terminals can be performed at low power, the power consumption of the terminal can be minimized.

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. Prior to this, terms and words used in the present specification and claims are to be interpreted in accordance with the technical idea of the present invention based on the principle that the inventor can properly define the concept of the term in order to explain his invention in the best way. It should be interpreted in terms of meaning and concept. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

Before explaining a point-to-point communication method based on orthogonal frequency division multiple access according to the present invention, the point-to-point communication system based on the orthogonal frequency division multiple access according to the present invention will be described with reference to FIGS. 2 and 3 as follows. .

In general, the assignment of OFDMA subcarrier hopping sequence information, as shown in Figure 2, 5 users to use the sub-carrier and the time (OFDM symbol interval) is divided into a method, the user (user) user 1 is the first in the OFDM symbol By using the subcarriers and using the fourth subcarrier in the second OFDM symbol, the five subcarriers are divided and used so that five users do not overlap each other.

Meanwhile, the allocation of OFDMA subcarrier hopping sequence information for point-to-point communication according to the present invention will be described below.

The present invention will be described assuming that the allocation of the OFDMA subcarrier hopping sequence information for point-to-point communication as described above to five users, but can be assigned without being limited to the number of users.

In addition, the following description will be omitted, but the assignment of OFDMA subcarrier hopping sequence information according to the present invention, the uplink time or frequency of the time division duplex (TDD) or frequency division duplex (FDD) by the diversity scheme It is assumed that it is made through subcarriers that are not used by neighboring terminals in a band.

Specifically, as shown in FIG. 3, the transmitting terminal 100 and the receiving terminal 300, that is, cellular terminals for point-to-point communication, use subcarrier sequences of users 1 to 4, and user 5 uses subcarriers in opposite directions. When using the sequence, when the point-to-point terminals perform channel sensing, it is possible to predict the subcarrier sequence that is not currently used in the vicinity.

Therefore, when point-to-point communication is performed by a subcarrier sequence, a communication link can be formed without affecting cellular communication, thereby maximizing resource utilization.

Hereinafter, a point-to-point communication system based on orthogonal frequency division multiple access as described above will be described.

As shown in FIG. 4, the secondary system for the OFDMA-based primary system of the present invention includes a transmitting terminal 100, a base station 200, and a receiving terminal 300.

The transmitting terminal 100 generates communication request information including the identification data of the receiving terminal 300 by a user's operation and transmits it to the base station 200, and the communication response information corresponding to the communication request information from the base station 200. Receive

In addition, according to the point-to-point OFDMA subcarrier hopping sequence information (hereinafter, 'point-to-point OFDMA information') received from the base station 200 receives the communication response information corresponding to the communication request information from the receiving terminal 300, and then the base station The communication request information is transmitted to the receiving terminal 300 without passing through 200.

In detail, the link setting for communication between the transmitting terminal 100 and the receiving terminal 300 is performed by using an empty frequency hopping sequence through channel sensing based on point-to-point OFDMA information received by the transmitting terminal 100. A request to send packet is transmitted, and a CTS (Clear To Send) packet is received from the receiving terminal 300 which receives the packet.

In this case, the channel sensing is performed through a sequence estimation of empty subcarriers for a predetermined time in all OFDM symbol intervals, and the subcarrier sequence is determined through sequence sensing of empty subcarriers for a predetermined time among several OFDM symbol intervals. The preset sensing signal to noise ratio (SNR) may be adjusted according to the relative positions of the transmitting terminal 100 and the receiving terminal 300, and the sensing time and the number may also be adjusted.

In addition, the transmitting terminal 100 may receive communication stop information from the base station 200 or the receiving terminal 300 to release the previously connected communication link.

Meanwhile, the base station 200 calculates the distance between the transmitting terminal 100 and the receiving terminal 300 according to the received communication request information and when the distance between the transmitting terminal 100 and the receiving terminal 200 exceeds a preset distance. In addition, the communication request information is transmitted to the receiving terminal 300 to transmit the received communication response information to the transmitting terminal 100 together.

On the other hand, when the calculated distance is within a predetermined distance, the point-to-point OFDMA information is generated and transmitted to the transmitting terminal 100 and the receiving terminal 300.

In addition, the reception terminal 300 transmits communication response information corresponding to the communication request information received from the base station 200 to the base station 200, receives point-to-point OFDMA information from the base station 200, and transmits a transmission terminal ( When receiving the communication request information from 100, and transmits the communication response information corresponding to the communication request information to the transmitting terminal (100).

In addition, by receiving the communication stop information from the base station 200 or the transmitting terminal 100 may release the previously connected communication link.

In the present invention described above, the point-to-point communication between the transmitting and receiving terminals by the point-to-point OFDMA information is described as performing a subcarrier hopping sequence, but the present invention is not limited thereto, and the subcarrier is interpreted as a spreading code. Thus, point-to-point communication is possible in the CDMA system as well.

According to the configuration of the point-to-point communication system based on the orthogonal frequency division multiple access as described above, as shown in FIG. 4, by performing the point-to-point communication 1 between the transmitting terminal 100 and the receiving terminal 300, Since communication can be performed at low power, the problem of interference (3) with the communication (2) of the other transmitting terminal can be minimized.

Hereinafter, a point-to-point communication method based on orthogonal frequency division multiple access according to the present invention will be described with reference to FIGS. 5 and 6.

First, the base station 200 receives the communication request information from the transmitting terminal 100 and senses the position of the receiving terminal 300 to determine it (S10).

As a result of the determination in step S10, when the distance between the transmitting terminal 100 and the receiving terminal 300 is within a predetermined range, the point-to-point OFDMA information including the subcarrier hopping sequence for the point-to-point communication is generated to transmit and receive It transmits to the terminal (S20), and performs point-to-point communication according to the OFDMA information received by the transmitting terminal and the receiving terminal (S30).

Here, the subcarrier hopping sequence is determined through channel sensing of an empty subcarrier sequence for a preset time period among a plurality of OFDM symbol intervals, and the channel sensing is performed by adjusting the sensing time and the number of times according to the relative distance between the transmitting terminal and the receiving terminal. It is possible.

In addition, after step S20, point-to-point communication in a CDMA system is possible by interpreting OFDMA information received by a transmitting terminal and a receiving terminal as a spreading code (S40).

On the other hand, when the determination result of step S10, when the distance between the transmitting terminal and the receiving terminal exceeds a predetermined range, the communication request information is transmitted to the receiving terminal to transmit the received communication response information to the transmitting terminal (S50).

On the other hand, as shown in FIG. 7 before step S10, through a request to send (RTS) / clear to send (CTS) packet exchange between the transmitting terminal and the receiving terminal according to OFDMA information previously stored in the transmitting terminal and the receiving terminal. Point-to-point communication may be performed to replace steps S10 to S50 (S60).

As described above and described with reference to a preferred embodiment for illustrating the technical idea of the present invention, the present invention is not limited to the configuration and operation as shown and described as such, it departs from the scope of the technical idea It will be apparent to those skilled in the art that many modifications and variations can be made to the present invention without this. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

1 shows a communication link always established through a base station in accordance with conventional OFDMA cellular communication.

2 is a diagram illustrating an example of subcarrier allocation using Latin Square in a point-to-point communication method based on orthogonal frequency division multiple access according to the present invention.

3 is a diagram illustrating an example of frequency allocation for point-to-point communication in an environment using Latin Square in an orthogonal frequency division multiple access based point-to-point communication method according to the present invention.

4 is a block diagram of a point-to-point communication system based on orthogonal frequency division multiple access according to the present invention;

5 is a flowchart illustrating a point-to-point communication method based on orthogonal frequency division multiple access according to the present invention.

6 is a flowchart illustrating step S40 of a method for point-to-point communication based on orthogonal frequency division multiple access according to the present invention.

7 is a flowchart illustrating step S60 of a method for point-to-point communication based on orthogonal frequency division multiple access according to the present invention.

Claims (6)

  1. In the point-to-point communication method based on orthogonal frequency division multiple access,
    (a) the base station receiving the communication request information from the transmitting terminal searching (sensing) and determining the position of the receiving terminal;
    (b) when the distance between the transmitting terminal and the receiving terminal is within a preset range as a result of the determination of step (a), generating point-to-point OFDMA information including subcarrier hopping sequences for point-to-point communication and generating the transmitting terminal and Transmitting to a receiving terminal;
    (c) performing point-to-point communication according to the OFDMA information received by the transmitting terminal and the receiving terminal; And
    (d) if the distance between the transmitting terminal and the receiving terminal exceeds a preset range as a result of the determination of step (a), transmitting the communication response information to the receiving terminal and transmitting the received communication response information to the transmitting terminal; Making; Orthogonal frequency division multiple access based point-to-point communication method comprising a.
  2. The method of claim 1,
    After step (b),
    (c ') performing point-to-point communication in a CDMA system by interpreting OFDMA information received by the transmitting terminal and the receiving terminal as a spreading code; Orthogonal frequency division multiple access based point-to-point communication method further comprising a.
  3. The method of claim 1,
    The subcarrier hopping sequence,
    Orthogonal frequency division multiple access based point-to-point communication method characterized in that determined by the channel search (sensing) of the empty subcarrier sequence for a predetermined time from a plurality of OFDM symbol interval.
  4. The method of claim 3, wherein
    The channel discovery (sensing) is,
    Orthogonal frequency division multiple access based point-to-point communication method characterized in that the sensing time and the number is adjusted according to the relative distance between the transmitting terminal and the receiving terminal.
  5. delete
  6. The method of claim 1,
    Before step (a),
    (e) performing point-to-point communication through RTS (Request to Send) / CTS (Clear to Send) packet exchange between the transmitting terminal and the receiving terminal according to the OFDMA information previously stored in the transmitting terminal and the receiving terminal. Substituting to (c); Orthogonal frequency division multiple access based point-to-point communication method further comprising a.
KR1020080087543A 2008-09-05 2008-09-05 Point-to-point communication method using ofdma KR100961559B1 (en)

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JP2007500988A (en) 2003-05-19 2007-01-18 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィKoninklijke Philips Electronics N.V. Method and apparatus for supporting P2P communication in TDDCDMA

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007500988A (en) 2003-05-19 2007-01-18 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィKoninklijke Philips Electronics N.V. Method and apparatus for supporting P2P communication in TDDCDMA

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