WO2013141460A1

WO2013141460A1 - Method and apparatus for reliable communication by ack aggregation in directional wireless communication system

Info

Publication number: WO2013141460A1
Application number: PCT/KR2012/008966
Authority: WO
Inventors: 조성래; 박래혁; 유정석
Original assignee: 중앙대학교 산학협력단
Priority date: 2012-03-23
Filing date: 2012-10-30
Publication date: 2013-09-26

Abstract

The present invention relates to a method and an apparatus for reliable communication by means of an ACK aggregation in a directional wireless communication system. According to one embodiment of the present invention, a communication method of a receiver in a directional wireless communication system comprises: a step of receiving a multicasted i-number (wherein, i is an integer) of data frames from a first sector of a sender antenna beam; a step of checking the ACK aggregation scheduling information included in at least one of the i-number of data frames; and a step of aggregating the ACK information for the i-number of data frames based on the ACK aggregation scheduling information. The aggregation of the ACK information includes receiving ACK information of the previous receiver that belongs to the first sector based on the order included in the ACK aggregation scheduling information, or transmitting ACK information to the next receiver based on said order.

Description

Reliable communication method and device therein through Eck aggregation in directional wireless communication system

The present invention relates to a method and apparatus for reliable communication through Eck aggregation in a directional wireless communication system. Here, the directional wireless communication system may be a wireless local area network (WLAN) capable of high-speed data service of 1Gbps or more, such as IEEE 802.11ad.

Recently, researches on wireless local networks capable of high-speed data service of 1Gbps or more have been actively conducted. High-speed data services use high directional antennas to ensure high throughput using frequencies in the 60 GHz band.

Services using WLAN based on IEEE 802.11ad may include reliable multicasting services.

Multicasting services can be very important in many applications, such as software updates, alarm signal transmissions, and so on.

To date, there are not many studies related to reliable multicasting protocols for directional antennas, and many studies have been conducted only on wireless networks.

In the prior art associated with multicasting, the sender multicasts the frame to all receivers, and the ACKs of each of the receivers are scheduled to prevent ACK explosion problems. In this case, the transmitting end may maintain a bitmap table that records a receiver for which no ACK is received.

The transmitting end may retransmit the original multicast frame including the bitmap information, and the receiver that does not receive the frame may correct the error.

As such, since all receivers in the prior art must transmit ACK, delay may inevitably occur, and throughput of the entire communication system may be degraded. The larger the number of receivers, the lower the overall throughput of the communication system will be.

On the other hand, in the NAK-based multicasting method, proper control may not be performed when all transmission frames fail.

In a hybrid system using both ACK and NAK, a receiver and a transmitter selected as a leader may perform ACK-based multicasting, and the remaining receivers may perform NAK-based multicasting. At this time, in the case of receivers other than the receiver selected as the hybrid system, the same problem may occur as the NAK-based multicasting method.

The present invention provides a reliable communication method through Eck aggregation in a directional wireless communication system.

In addition, the present invention provides a communication system capable of avoiding delay and collision of an ACK in a directional wireless communication system.

In a directional wireless communication system according to an embodiment of the present invention, a communication method of a receiver includes: receiving i data frames (i is an integer) multicasted in a first sector of a transmitter antenna beam; Identifying ACK aggregation scheduling information included in at least one of the i data frames; And collecting ACK information for the i data frames based on the ACK aggregation scheduling information, wherein the collection of the ACK information is performed in the first sector according to the order included in the ACK aggregation scheduling information. Receiving the ACK information of the previous receiver belonging to, or transmitting the ACK information to the next receiver in the above order.

According to an aspect of the present invention, there is provided a communication apparatus of a directional wireless communication system, comprising: a receiver configured to receive i data frames (i is an integer) multicasted in a first sector of a transmitter antenna beam; A control unit which checks ACK aggregation scheduling information included in at least one of the i data frames; An ACK information collecting unit for collecting ACK information for the i data frames based on the ACK aggregation scheduling information, wherein the ACK information collecting unit includes the first sector according to an order included in the ACK aggregation scheduling information; Receive ACK information of the previous receiver belonging to, or transmits the ACK information to the next receiver in the above order.

In a directional wireless communication system according to an embodiment of the present invention, a sender communication method includes multicasting i (i is an integer) data frames in a first sector of an antenna beam; Switching the antenna beam to a second sector and multicasting the i data frames in the second sector; And switching the antenna beam to the first sector after completing the multicasting of the second sector, and receiving aggregated ACK information of receivers belonging to the first sector, wherein at least one of the i data frames Contains ACK aggregation scheduling information.

According to another aspect of the present invention, a communication apparatus of a directional wireless communication system includes: an antenna unit configured to multicast a data frame using an antenna beam; An antenna switching unit for switching the antenna beam; And a control unit for generating ACK aggregation scheduling information, wherein the antenna unit multicasts i data frames (i is an integer) to a first sector in a first period and multiplies to a second sector in a second period. Casting, wherein the antenna switching unit switches the antenna beam to the second sector after the first section and the reporting section, switches the antenna beam to the first sector after the second section, and the antenna unit After the second interval, the aggregated ACK information of the receivers belonging to the first sector is received.

A communication method of a source node in a directional wireless communication system according to an embodiment of the present invention includes the steps of: generating, by the source node, a beam table including beam direction information of each of the destination nodes in communication coverage; Scheduling an ACK aggregation order for a first sector of an antenna beam based on the beam table; Broadcasting i (i is an integer) data frames in the first sector; Switching the antenna beam to a second sector and performing broadcasting in the second sector; And switching an antenna beam to the first sector after completing broadcasting of the second sector, and receiving aggregated ACK information of destination nodes belonging to the first sector, wherein at least one of the i data frames is received. One includes ACK aggregation 1 scheduling information generated based on the beam table.

A communication apparatus of a directional wireless communication system according to an embodiment of the present invention, the antenna unit for broadcasting a data frame using a tena beam; An antenna switching unit for switching the antenna beam; And a controller configured to generate a beam table including beam direction information of each of the destination nodes in communication coverage, and to schedule an ACK collection order based on the beam table, wherein the antenna unit includes: broadcast i data frames to a first sector in a second sector and broadcast to a second sector in a second section, and the antenna switching unit performs the antenna beam after the first section and the reporting section. Is switched to the second sector, the antenna beam is switched to the first sector after the second period, and the antenna unit receives collected ACK information of destination nodes belonging to the first sector after the second period. do.

According to the present invention, a reliable communication method through Eck aggregation in a directional wireless communication system is possible, and delay and collision of an ACK can be avoided in the directional wireless communication system.

The directional wireless communication system according to the present invention can avoid delay and collision of the ACK.

1 is a view for explaining an example of a network topology of K = 4 according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of scheduling according to a communication scenario of a network illustrated in FIG. 1.

3 illustrates an example of ACK aggregation using a bitmap, according to the communication scenario of FIG. 1.

4 shows an example of comparing reliability based on frame error rate (FER).

5 shows an example of comparing reliability based on frame loss rate (FLR).

6 shows an example of comparing ACK collection latency on the basis of frame error rate (FER).

7 illustrates a communication method of a receiver in a directional wireless communication system for transmitting and receiving data through a beam of a directional antenna according to an embodiment of the present invention.

8 shows an example of the configuration of a communication device (receiver) of a directional wireless communication system according to an embodiment of the present invention.

FIG. 9 illustrates a sender communication method in a directional wireless communication system for transmitting and receiving data through a beam of a directional antenna according to an embodiment of the present invention.

10 shows an example of the configuration of a communication device (sender) of a directional wireless communication system according to an embodiment of the present invention.

11 shows an exemplary network topology according to an embodiment of the invention where N = 4 and M = 13.

12 shows an example of comparing reliability based on frame error rate (FER).

13 shows an example of comparing reliability based on frame loss rate (FLR).

14 illustrates an example of comparing transmission delays based on a frame error rate (FER).

15 shows an example of the configuration of a communication device (source node) of the directional wireless communication system according to the embodiment of the present invention.

16 illustrates a communication method of a source node in a directional wireless communication system for transmitting and receiving data through a beam of a directional antenna according to an embodiment of the present invention.

17 shows an example of the configuration of a communication device (destination) of the directional wireless communication system according to the embodiment of the present invention.

18 is a diagram illustrating an example of communication timing in the scenario of FIG. 11.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the principle of spatially pipelined ACK aggregation reliable multicast (SPARM) applied to the present invention will be described. Hereinafter, a communication method and a communication device using the SPARM will be described.

Embodiments proposed herein relate to an ACK-based reliable multicast protocol in a directional wireless communication system. In this case, the directional wireless communication system refers to a wireless communication system using a directional antenna such as 60GHz technology.

An ACK based scheme may have a problem of ACK explosion and ACK collection latency. In this case, the ACK collection latency refers to a delay time for receiving the ACK.

Embodiments of the present invention can increase system performance by solving the problems of ACK explosion and ACK collection latency. The problem of ACK explosion and ACK collection latency can be solved or alleviated by "spatial reuse" and "pipelining of ACK aggregation" of directional antennas. Here, "aggregation" may mean a series of processes of merging ACKs and transmitting the merged ACKs to the transmitter S without interference. Of course, the term "aggregation" may in some cases mean merging ACK itself.

<SPARM>

In the present specification, a directional wireless communication system is assumed to be an antenna beam switching system in which K (K is an integer) beam patterns are non-overlapping. Here, the antenna beam switching system may be, for example, a system conforming to the IEEE 802.11 MAC standard. Also, for example, a 60 GHz wireless communication system may switch antenna beams and may be implemented such that the plurality of beams do not overlap. Here, the switching of the antenna beam may be to spatially move the beam radiated through the antenna.

In directional communication, when one beam is transmitted or received, the remaining beams are blocked. Thus, embodiments of the present invention do not consider the case where all K beams are multicast simultaneously. That is, the antenna beam may be sequentially multicasted from 0 to K-1 th.

As shown in Fig. 1, the transmitter S is a receiver.

Angle

Save it, and

Beamforming may be performed using. In this case, j is an index for distinguishing the receivers, and i is an index for the beam of the transmitter S. In other words,

Denotes the j-th receiver in the region capable of receiving the i-th antenna beam of the transmitter S.

Is

It may be obtained by an angle of arrival (AOA) estimation using a registration frame of.

Transmitter S

Relative distance to

Can be estimated. At this time, the relative distance

Can be obtained, for example, by measuring the received power of a registration frame that includes the transmit power information of the receiver.

As shown in FIG. 1, the multicast group of the transmitter S may be defined as R _i for the antenna beam (which may be referred to as 'beam' for short) i. In other words,

N _i is the number of receivers of R _i . Multicast groups can also be represented as "sectors of antenna beams". For example, in FIG. 1, the transmitter S may multicast to each of four antenna beam sectors R ₀ , R ₁ , R ₂ , and R ₃ .

In the SPARM technology according to the embodiment of the present invention, the transmitter S may multicast data frames in a circular fashion from R ₀ to R _K-1 . That is, in FIG. 1, the transmitter S may perform beamforming on R ₀ and then perform beamforming on R ₁ .

After multicasting the data frames, the transmitter S needs to receive an ACK.

In this case, it may be an important issue when to set an optimal time for transmission of ACKs by each of the receivers. The ACK transmission may be performed after data multicasting up to R _K-1 is completed. However, from the receiver's point of view, sending an ACK while transmitter S performs multicasting may be more efficient in reducing the overall communication delay, as long as it does not interfere with transmitter S performing multicasting.

In the SPARM technique according to an embodiment of the present invention, ACKs of receivers belonging to R _i are aggregated to reduce the ACK collection latency time. In this case, the collection of ACKs means that the transmitter S multicasts the data frame in the beam (i + 1)% K (i = {0, 1, ..., K-1 and% means modulo operation}). May be collected. The aggregation concept of the ACKs and the aggregation schedule are described in more detail with reference to FIG. 2.

In FIG. 2, T ₀ and T ₁ represent the multicasting periods of beam 0 and beam 1, respectively, and T _r represents the reporting duration of the collected ACKs.

Referring to FIG. 2, the transmitter S multicasts a data frame with R ₀ in a T _{0 period} . After completing multicasting for R ₀ , the transmitter S switches the beam to 1 and multicasts the data frame to R ₁ in the T _{1 period} . ACK of the receivers belonging to R ₀ in the T ₁ interval is collected.

Since there may be multiple multicast frames for which no ACK has been identified, the transmitter S may track and maintain whether an ACK is received for each of the frames.

Each of the receivers maintains a bitmap for the multicast frame. In this case, the bitmap may be used to indicate whether the i-th frame has been successfully received. For example, "1" in the bitmap indicates that the frame has been successfully received. By logically ANDing the bitmaps, the final receiver can know which frame was successfully received for each of all receivers. In this case, the final receiver may be a receiver that collects the ACK and reports it to the transmitter S. The logical AND operation may be performed in units of bits of the bitmap.

In FIG. 3, the first sequence number of the bitmap is 0, and the ACK aggregation is

from

And then

From

Assume that they are scheduled in the order of.

Referring to FIG. 3, the bitmap frame includes a bitmap header H. H may include a first sequence number (SN) of the bitmap and a frame number of a frame targeted for ACK. The i th bit of the bitmap may indicate whether the i th frame has been successfully received.

Referring to Figure 3, the receiver

Is

By ANDing the bitmap received from it and its own bitmap, it can be seen that the first data frame has been missed. Likewise,

Is

By ANDing the bitmap received from its own bitmap, we know that the first (SN (1)), third (SN (3)) and fourth (SN (4)) data frames are missing. Can be. In step 2 of FIG.

If a data frame with a sequence number of 2 is received while a data frame with a sequence number of 1 is not received, may designate a second bit of its ACK bitmap as "0".

Unlike the prior art, in the SPARM technique according to the embodiment of the present invention, the transmitter S does not necessarily maintain a bitmap for each of the receivers. That is, in the SPARM technique according to the embodiment of the present invention, the bitmap table indicates whether reception of each data frame is successful. Accordingly, according to the SPARM technique according to the embodiment of the present invention, the bitmap table has a feature that is independent of the number of receivers and is scalable. In the present specification, the bitmap table may be a lookup table that records the bitmap reported to the transmitter S by the final receiver.

In Figure 1,

from

Assuming an ACK is sent to

Beam for transmission of the ACK is that belong to R ₁ while the transmitter S multicasting to R ₁

May cause interference. Thus, ACK aggregation or aggregation scheduling needs to be carefully designed.

1 to 3, ACK aggregation for R ₀ may be performed to prevent interference with R ₁ .

from

And then

From

It is scheduled in order. sure,

The report from the transmitter to the transmitter S is delayed until the multicasting of R ₁ ends.

Referring back to FIG. 2, in the interval where the transmitter S multicasts the data frame to R ₁ .

,

And

Collects ACKs.

Final receiver

Waits for the multicasting of R ₁ to end and reports the aggregated ACK to transmitter S. In other words,

Transmits a bitmap corresponding to "aggregated ACK to be transmitted" generated in step 3 of FIG. 2 to the transmitter S. FIG.

As can be seen in the example described in FIGS. 1-3, transmitter S receives only one ACK report for R ₀ . Therefore, the SPARM technique according to the embodiment of the present invention can solve the problem of ACK explosion (implosion) regardless of the number of transmitters.

In an embodiment of the invention, the ACK aggregation scheduling may be determined by the transmitter S. The transmitter S may determine an ACK collection order according to the following two policies (hereinafter, referred to as an 'collecting scheduling policy').

Policy 1: ACK Collection Schedule is Angled with Transmitter S

Should be sorted in order of decreasing. In other words,

If,

Is

ACK is collected. In this case, a and b are indices for distinguishing receivers, respectively. In the example of FIG. 1,

from

If collected in the order of, no interference to R ₁ occurs,

from

In the order of, belonging to R ₁

It can be seen that it can cause interference.

Here, an angle formed with the transmitter S refers to an angle formed by the connection line between s and the receiver with respect to the starting line of Ri, as shown in FIG. 1. In this case, it is assumed that the transmitter S knows the location information of each of the receivers.

Policy 2:

If ACK collection schedule is the distance from transmitter S

Should be sorted in increasing order. As shown in FIG. 1,

And

Is the same angle as the transmitter S,

to be. At this time,

from

ACK aggregation (i.e., ACK transmission using a directional antenna) to a channel does not interfere with transmitters S and R ₁

from

ACK aggregation to the interference may occur.

< Sender and Receiver Behavior >

The following pseudo code shows an example of an algorithm for the behavior of a transmitter.

Pseudo Code-The SPARM algorithm at the sender

Here, SN _i is the last sequence number of the frame to be ACK in the beam i,

Transfer buffer

This indicates the number of unacknowledged frames in. At this time,

Denotes a transmission buffer array for beam i. That is, the transmit buffer array may be a memory that stores a data frame that is a target of multicasting.

When the transmitter S is turned on, the transmitter S collects information of the receivers from the registration frame, where the registration frame is received from each of the receivers. In this case, the receiver information includes an AOA value, transmission power information, and the like. Subsequently, the transmitter S performs ACK aggregation scheduling in consideration of the aggregation scheduling policy described above, and sets SN _i of each beam to zero. Upon completion of the ACK aggregation scheduling, the transmitter S prepares for multicasting of the data frame.

Before the transmitter S transmits multicast frames, i.e., a data frame subject to multicasting,

And

Calculate 2,

And

Is the "time report (report time) of the final receiver in the R _i", "start time (start time) of the ACK for the first collected in the receiver R _i" and respectively. The report time refers to the time when the last receiver transmits a bitmap frame (ie, “aggregated ACK to be transmitted” generated in step 3 of FIG. 2) to the transmitter S.

And

May be expressed as Equation 1 and Equation 2, respectively.

In this case, T _data is a frame transmission time, T _ack is an ACK transmission time, and T _C is the current system time. sure,

And

In addition, information on the order of ACK aggregation (ie, the order list of receivers) is included in the multicast frame.

if,

> 0, i.e. if there is any frame for which no ACK has been received, the transmitter s

And

Multicast the corresponding data frame based on. Also, when a new data frame occurs

(In other words,

Transmitter S takes a new data frame

And

Transmit based on the value of SN _i . If transmitter S ends multicasting for R _i , unless an error occurs in the aggregation process,

The ACK collection at is complete. Transmitter s beam

In the T _ack interval

Receive a bitmap frame from the last receiver in the.

The transmitter checks the received bitmap frame to confirm that the data frame has been successfully received.

You can delete the data frame from it.

When the receiver is turned on, it is associated with the transmitter S through transmission of a registration frame. When the receiver successfully receives a multicast frame, i.e., a frame that is multicasted from the transmitter, it marks the SN _i- th bit of the bitmap as 1, as shown in FIG. Each receiver can know its collection order through a multicast frame. That is, since the multicast frame includes an order list of receivers, each of the receivers can know its own collection order.

As shown in FIG. 3, the first receiver of the ACK aggregation schedule relays its bitmap to the next receiver at Ts (i). The final receiver of the ACK aggregation schedule aggregates (ie, ANDs) the bitmap relayed (ie received from the previous receiver) with its bitmap and sends the aggregated bitmap to the transmitter at T _E (i). do. The receiver, which is not the first receiver or the last receiver, aggregates the received bitmap with its bitmap and sends the aggregated bitmap to the next receiver on the ACK aggregation schedule.

< PERFORMANCE EVALUATION example >

4 shows an example of comparing reliability based on frame error rate (FER).

5 shows an example of comparing reliability based on frame loss rate (FLR).

4 to 6 show a case where the data frame has a length of 1024 bytes and the ACK frame has a length of 2 bytes. 4 to 6, n denotes the number of nodes (receivers).

In this case, the reliability is a value obtained by dividing the number of transmission success frames by the number of transmission frames including a retransmission frame, and the ACK collection latency is a value obtained by measuring an average delay from transmission of a data frame to reception of an ACK.

Also through the performance measurement example, it can be seen that the SPARM technique according to the embodiment of the present invention reduces the problems of ACK explosion (implosion) and ACK collection latency (latency) compared to the prior art.

Hereinafter, specific embodiments of the "communication method and communication device using SPARM" will be described based on the principle of spatially pipelined ACK aggregation reliable multicast (SPARM). 1 to 3 may be applied to both the communication method and the description of the communication device to be described later.

The method shown in FIG. 7 may be performed by each of the receivers of FIG. 1.

In step 710, the receiver receives i data frames (i is an integer) multicasted in the first sector of the transmitter antenna beam. For example, the first receiver r ₀ ⁰ of FIG. 1 may receive five data frames in the first duration T ₀ of FIG. 2. In this case, the five data frames may be data frames corresponding to SN (0) to SN (4) in FIG. 3. In FIG. 3, it is assumed that a data frame corresponding to SN (0) includes “ACK aggregation scheduling information”, and SN (1) is the first frame targeted for ACK.

In step 720, the receiver checks ACK collection scheduling information included in at least one of the i data frames. The ACK aggregation scheduling information may include information on a sector-by-sector multicasting time, a report time of aggregated ACK information, and an aggregation order of ACK information.

That is, the ACK aggregation scheduling information may include "sector-specific multicasting time information" such as start and end times of each of T ₀ and T ₁ shown in FIG. 3.

In addition, the ACK aggregation scheduling information may include "report time information of aggregated ACK information" such as a start and end time of the Tr of FIG. 3.

In addition, the ACK collection scheduling information may include "information on the collection order of ACK information" such as "aggregation scheduling" described in <SPARM scheduling>.

In step 730, the receiver collects ACK information for the i data frames based on the ACK collection scheduling information.

In this case, "collecting ACK information" means generating a bitmap described in <SPARM> and <SPARM scheduling> and performing a series of processes of transmitting and receiving bitmaps.

Accordingly, the collection of ACK information receives ACK information of a previous receiver belonging to the first sector (eg, R _{0 in} FIG. 1) according to the order included in the ACK collection scheduling information, or the next receiver according to the order. And transmitting ACK information.

In this case, when the receiver for performing the method of FIG. 7 is r ₀ ¹ of FIG. 1, the “previous receiver belonging to the first sector” may be r ₀ ^{1 of} FIG. ¹ . Of course, when the receiver performing the method of FIG. 7 is r ₀ ² of FIG. ¹ , the "previous receiver belonging to the first sector" may be r ₀ ¹ .

In this case, when the receiver performing the method of FIG. 7 is r ₀ ⁰ of FIG. 1, the "next receiver" may be r ₀ ¹ .

As described with reference to FIG. 3, the aggregation of ACK information may be performed in a period T ₁ in which the transmitter antenna multicasts to a second sector (eg, FIG. R ₁ ).

The ACK information includes a bitmap that specifies whether to receive each of the i data frames. That is, the ACK information generated by each of the receivers and transmitted / received between the receivers is " Own ACK bitmap (or referred to as " magnetic bitmap ") " , 320, 330). The ACK information also includes "aggregated bitmaps" 311, 321, 331 generated by an AND operation.

The process of collecting the ACK information includes "generating a bitmap indicating whether to receive each of the i data frames" and "sending the bitmap to the next receiver".

For example, assuming that a receiver performing the method of FIG. 7 is r ₀ ⁰ , r ₀ ⁰ generates a bitmap 310 specifying whether to receive each of i data frames. Since r ₀ ⁰ is the receiver having the fastest aggregation order in the first sector, the AND operation is not performed. Thus, the "aggregated ACK Bitmap" of 311 r ₀ ⁰ is the same as 310 and, r ₀ ⁰ transmits an ACK frame 311 to ₀ r ¹ of the next receiver.

Assuming that the receiver performing the method of FIG. 7 is r ₀ ¹ , r ₀ ¹ generates an "own bitmap" 320 that specifies whether to receive each of the i data frames. r ₀ ¹ receives the bitmap 311 of the previous receiver r ₀ ⁰ . r ₀ ¹ performs an AND operation on the bitmap 311 of the previous receiver r ₀ ⁰ and the magnetic bitmap 320 to generate an “aggregated bitmap 321”. r ₀ ¹ transmits the "aggregated bitmap 321" to r ₀ ² .

Assuming that the receiver performing the method of FIG. 7 is r ₀ ² , r ₀ ² generates an “own bitmap” 330 that specifies whether to receive each of the i data frames. r ₀ ² receives the bitmap 321 collected from the previous receiver r ₀ ¹ . r ₀ ² performs an AND operation on the aggregated bitmap 321 and the magnetic bitmap 330 to generate an “aggregated bitmap 331”. r ₀ ² sends an “aggregated bitmap 331” to the transmitter.

At this time, r ₀ ² is the second sector after the multi-cast on (for example, R ₁ in Fig. 1) complete reporting period (for example, T _r in Fig. 2), aggregate the ACK information of the transmitter " Aggregated Bitmap 331 "

Referring to the "aggregated bitmap 331" illustrated in FIG. 3, it can be seen that the first 301, third 303, and fourth 305 data frames have failed to be transmitted.

The structure shown in FIG. 8 may be a structure of each of the receivers of FIG. 1. Thus, the receiver shown in FIG. 8 may perform the method shown in FIG. 7.

Referring to FIG. 8, the receiver includes a receiver 810, a controller 820, and an ACK information collector 830.

The receiver 810 receives i data frames (i is an integer) multicasted in the first sector of the transmitter antenna beam. The receiver 810 may include a directional antenna (not shown) that is switchable for each preset sector.

The controller 820 checks ACK aggregation scheduling information included in at least one of i data frames. The controller 820 may include at least one processor. In this case, the at least one processor may be configured to control the overall operation of the receiver.

The ACK information collecting unit 830 collects ACK information for the i data frames based on ACK aggregation scheduling information.

The ACK information collecting unit 830 may receive ACK information of a previous receiver belonging to the first sector according to the order included in the ACK collection scheduling information, or may transmit ACK information to the next receiver according to the order.

The ACK information collector 830 may include a bitmap generator 831, an AND operator 833, and a transmitter 835.

The bitmap generator 831 generates an "own bitmap" that specifies whether to receive each of the i data frames.

The AND operator 833 receives the bitmap of the previous receiver and ANDs the bitmap and the magnetic bitmap of the previous receiver. Of course, the AND operator 833 may receive the bitmap 321 collected from the previous receiver. Here, the bitmap 311 of the previous receiver or the bitmap 321 collected from the previous receiver is received through the antenna of the receiver 810.

The transmitter 835 transmits an "aggregated bitmap" reflecting the result of the AND operation to the transmitter. Of course, the transmitter 835 may transmit the "aggregated bitmap" reflecting the result of the AND operation to the next receiver.

The method shown in FIG. 9 may be performed by transmitter S of FIG.

In step 910, the transmitter multicasts i (i is an integer) data frames in the first sector (eg, R ₀ ) 110 of the antenna beam. In this case, at least one ACK aggregation scheduling information of the i data frames is included. As illustrated in FIG. 7, "ACK aggregation scheduling information" may be included in a data frame corresponding to SN (0) of FIG. 3.

In step 920, the transmitter switches the antenna beam to the second sector (eg, R _{1 of} FIG. ₁ ) 120.

In step 930, the transmitter multicasts the i data frames in the second sector.

In step 940, after the multicasting of the second sector is completed, the transmitter switches the antenna beam to the first sector and receives aggregated ACK information of receivers belonging to the first sector. As illustrated in FIG. 3 and FIG. 7, the collected ACK information 331 includes a bitmap that specifies whether reception is successful for each of i data frames. Each of the i bits included in the bitmap represents a result of performing an AND operation on whether the i th data frame of each of the receivers belonging to the first sector is successfully received.

As described in "Policy 1" of <SPARM Scheduling>, the order of collecting ACK information may be determined in order of receivers having the angle with the sender in the receiver having the angle with the sender being large.

That is, the angle formed by the connecting line 102 of the reference axis 101 and the first receiver (r ₀ ¹ ) 111 in FIG.

silver

Since it is larger, the collection order of ACK information is

From

Are scheduled in order.

In addition, as described in " Policy 2 " of < SPARM Scheduling >, the order of collecting ACK information is determined in order of receivers having a shorter distance to the sender in receivers having a shorter distance to the sender.

The structure shown in FIG. 10 may be the structure of the transmitter S of FIG. 1. Accordingly, the communication device shown in FIG. 10 may perform the method shown in FIG. 9.

Referring to FIG. 10, the transmitter includes an antenna unit 1010, an antenna switching unit 1020, and a controller 1030.

The antenna unit 1010 multicasts a data frame using an antenna beam.

The antenna unit 1010 multiplies i (i is an integer) data frame into a first sector (for example, 110 in FIG. 1) in a first duration (for example, T ₀ of FIG. 2). Casting is performed to multicast to the second sector (120 in FIG. 1) in the second section (T _{1 in} FIG. 2).

The antenna unit 1010 receives the collected ACK information of the receivers belonging to the first sector after the second interval.

The antenna switching unit 1020 switches the antenna beam.

The antenna switching unit 1020 switches the antenna beam to the second sector after the first period and the reporting period T _r , and switches the antenna beam to the first sector after the second period.

The controller 1030 generates ACK aggregation scheduling information. Of course, the controller 1030 may include at least one processor designed to control the overall operation of the transmitter.

The controller 1030 may determine an order in which the ACK information is collected in the order of the receivers having the angle with the sender having the smallest angle with the sender.

The controller 1030 may determine the collection order of the ACK information in the order of the receiver having the short distance to the sender from the receiver having the short distance to the sender.

< BTBR (Beam Table-based Reliable Broadcast) Technique >

In directional communication, when one beam is transmitted or received, the remaining beams are blocked. Thus, embodiments of the present invention do not consider the case where all N beams (N is an integer) are broadcast simultaneously. That is, the antenna beam may be broadcast sequentially from 0 to N-1 th.

In addition, in the present specification, a directional wireless communication system is a single hop environment, and a source (hereinafter, referred to as 'S') has M destinations (M is an integer) of destinations (d _i ,

Act as a broadcast sender for. In this case, S may use N discrete beams covering 360 °.

In addition, in the present specification, D _n is the n th beam of S (

) Means a group of destinations located in an area for receiving a). For example, in FIG. 11, D ₀ = {d ₂ , d ₄ , d ₅ , d ₁₂ }. B _{i, j} means a beam number from node i to node j. If node i cannot make beam transmission to node j, i.e., there is no communication link between node i and node j, or if node i does not have information about node j, B _{i, j} is set to -1. That is, "-1" in Table 1 indicates a case in which there is no communication link between node i and node j or node i does not have information about node j.

11 illustrates an exemplary network topology in accordance with an embodiment of the invention where N = 4 and M = 13.

Initially when a directional wireless communication system is constructed, no node knows the beam information of other nodes. That is, in the beginning when the network is configured, node i may not know information about B _{i and j} even when node j is present in communication coverage.

However, when the network is sufficiently established (established), each node can know the beam information of the other nodes through the exchange of data frames or the reception of a hello message. In this case, the beam information means all information related to beam forming such as a beam forming schedule of another node or a beam direction. That is, the beam information may include various information for performing communication through the directional antenna, and may be information defined in a communication standard related to 60 GHz technology.

For example, the data frame transmitted by sender S (i.e., node i is sender S) at the beginning of the network setup may be "(1) B _{i, j} list", "(2) B _{j, i} list May include ". In this case, the list of B _{i, j} is, for example, each row described in [Table 1], and the list of B _{j, i} may be each column, described in [Table 1], for example. have. At this time, the node i and the node j is located at a distance that can communicate with each other. Nodes in the network may generate a beam table as shown in Table 1 and store the beam table based on beam information exchanged or received at the initial network setting. This series of processes for generating the beam table will be referred to as "beam table caching".

Table 1 Beam Table Example of Sources in FIG.

S will be referred to as a sender set, and R (or D) will be referred to as a receiver set. At this time, the beam table is a matrix

It can be expressed as

< ACK Combination >

In the BTRB technique, the sender S can multicast the data frame in a circular fashion from D _n to D _{(n + 1)% N} (% means modulo operation). That is, in FIG. 11, after completing the broadcasting (first broadcasting) of the data frame for D ₀ , the source node S switches beams to 1 and broadcasts the data frame to D ₁ (second broadcasting). Can be.

From the receiver's point of view, sending an ACK while the sender S performs broadcasting may be more efficient in reducing the overall communication delay unless it interferes with the sender S performing the broadcasting.

That is, while sender S broadcasts a frame to D ₁ , it is more efficient for nodes belonging to D ₀ to combine the ACKs for the first broadcast to reduce communication delay.

In this case, “combination of ACKs” may mean a series of processes of merging ACKs and transmitting the collected ACKs to the source node S without interference. Thus, "ACK combining" is used herein in the same sense as "ACK aggregation". Of course, the term "combination of ACKs" may in some cases mean merging the ACKs themselves.

In the BTRB technique, "combination" may be performed by a logical AND operation performed in bits of the bitmap of each of the receivers in D _n . At this time, each of the receivers maintains a bitmap for the broadcast frame. In this case, the bitmap may be used to indicate whether the i-th frame has been successfully received. For example, "1" in the bitmap indicates that the frame has been successfully received. By logically ANDing the bitmaps, the final receiver can know which frame was successfully received for each of all receivers. In this case, the final receiver may be a receiver that collects ACKs and reports them to the source node S.

If the k-th bit of the bitmap is set to 1, it means that the k-th frame has been successfully received. If it is set to 0, it may represent that the k-th frame has not been successfully received.

To share the bitmaps, receivers (ie, destinations) send and receive bitmap frames that include the bitmap header H. H may include a first sequence number (SN) of the bitmap and a frame number of a frame targeted for ACK. The i th bit of the bitmap may indicate whether the i th frame has been successfully received.

For example, when the bitmap generated by d ₄ of FIG. 11 is the same as FIG. 1 in the following example, d ₄ is the first (SN (1)), second (SN (2)), second ( It means that both SN (3)) and the fourth (SN (4)) data frame have been successfully received.

If the bitmap generated by d ₁₂ of FIG. 11 is the same as that of FIG. 2, d ₁₂ indicates that the first (SN (1)) data frame was not successfully received in the first broadcasting. In this case, it is assumed that the ACK combining is performed in the order of d ₄ , d ₁₂ .

d ₁₂ performs a logical AND operation on its bitmap (left bitmap to the left of the arrow) and the bitmap (right bitmap to the left of the arrow) received from d ₄ to form a combined bitmap such as the right of the arrow. Create The combined bitmap is transmitted to the next receiver (eg, d ₂ of FIG. 11).

In BTRB techniques, ACK combination of D _i shall not interfere with the broadcasts of the sender of D _{(i +1)% N.} In Figure 11, for the sender of the broadcast to the D _1, d _2, if the transmission itself of the bitmap, d ₄ d ₂ of the transmission causes interference to the sender, and D _1. Therefore, interference by such ACK combining can be prevented based on the beam table of [Table 1]. That is, the order of ACK combining must be carefully determined to avoid interference.

In FIG. 11, the order of ACK combining may be scheduled as follows.

ACK combining order: d ₄ to d ₁₂ , d ₁₂ to d ₂ , d ₂ to d ₅ ,

In this case, d ₅ is a final receiver (or destination) and reports the combined ACK to sender S.

As described above, according to the ACK combining order, interference with the sender and D ₁ due to the ACK combining of D ₂ does not occur. At this time, the report to the sender S of d ₅ is delayed until the broadcasting (second broadcasting) for D ₁ ends. That is, when the second broadcasting is completed, the sender S switches the beam again to receive the "combined bitmap" from d ₅ .

In Figure 11, the same as from d ₂ illustrated the "coupled to bit map" transmitted to d ₅ Figure 4, in the case where the bit map generated by the d ₅ as shown in Fig. 5 illustrates, d ₅ is the bitwise AND The operation (operation in frame sequence order) generates the "combined bitmap" shown to the right of the arrow in the example FIG.

d ₅ reports the "combined bitmap" to sender S, which sends first (SN (1)), third (SN (3)) and fourth via "combined bitmap" received from d ₅ . It can be seen that the (SN (4)) data frames are missing.

In the BTRB technique, the scheduling of the ACK combining order is determined by the source node. That is, the source node (sender S) schedules the ACK combining order.

The sender S performs the following four steps to schedule the ACK combining order for D _n .

step 1: the source node from the beam table

And

Extract At this time,

Is beam information for communication of nodes in D _n ,

Is beam information that should not be used for ACK combining because it interferes with the broadcasting of sender S. (A) and (b) of [Table 2] for the scenario of [Table 1], respectively

And

Indicates.

step 2: The source node is a candidate link matrix (

Calculate At this time,

Denotes beam information of D _n that may be used for combining ACK in a time interval in which the source node S performs broadcasting for D _{(i +1)% N.} In other words,

May be defined as shown in [Equation 5].

The operator of Equation 5 is that each sender

in

Means a process of removing a beam number matched with. Here, the result of removing the beam number may be marked as "-1". In Table 1 and Table 2, 0, 1, 2, 3 represent beam numbers at each node. For example, the beam information of sender d ₂ in (a) of [Table 2] is {-1, 2, 3, 1} and the beam information of sender d ₂ in (b) is {2, 1, -1, 2, 2}, {-1, 2, 3, 1} is changed to {-1, -1, 3, -1} as shown in (c). That is, d ₂ may not use

beam numbers

1 and 2 that interfere with sender S or D ₁ in the corresponding time interval, and may transmit a frame through beam 3 only for receiver d ₅ .

(C) of [Table 2]

As shown in FIG. 11, it can be seen that beamforming (ie, frame transmission) from d ₂ to d ₅ , d ₄ to d ₂ , d ₅ , and d ₁₂ can be performed without interference, as illustrated by the arrow shown in FIG. 11.

step 3: The source node determines the ACK combining order when step 2 is completed. At this time,

Is defined as a single path connection (connecting path) to another destination belonging to D _n in the destination belongs to D _n. here,

And L is

It means the number of paths obtained from. The source node may select an ACK combining order set C _n that may be defined as shown in Equation 6.

In equation (6)

Denotes the length of the array f. For example, in the scenario of Table 1, C ₀ = {d ₄ , d ₂ , d ₅ }. Of course, C ₀ = {d ₄ , d ₁₂ , d ₂ , d ₅ }. When C ₀ = {d ₄ , d ₂ , d ₅ }, d ₁₂ may be a unicast target node described later.

step 4: Depending on the communication conditions of the network, the "Hello message" of some destinations may be lost for a significant time period. In this case, the beam table information may not be useful. In case of a poor communication environment, ACK combining cannot be performed, and the ACK must be unicast to the source node. If the set of destinations to unicast an ACK from home D _n U _n d, the source node U _{_n} = D _n - can be calculated as C _n. In this case, the unicast order from the destination belonging to U _n may be scheduled according to an increase in the order of the node ID.

< BTRB Protocol >

SN _n is the last sequence number of the frame to be ACK in the beam n, Q _n means a transmission queue (queue) for the beam n. At this time, the transmission queue is a kind of buffer provided in the node and stores the frame. After determining the ACK combining order, the source node prepares to transmit a data frame.

At this time, the source node should inform the destinations in D _n of information on the start time and the end time of the ACK combining.

Is defined as the start time of ACK combining by the first destination in C _n ,

Is defined as the reporting time at which the last destination in C _n reports the bitmap frame (ie, the combined bitmap) as the source. And,

Is defined as the current system time before the source node broadcasts the data frame to D _n ,

Is defined as the frame transmission time,

Is defined as the ACK transmission time.

After the source node broadcasts a data frame to D _n , the source node

During the interval

Wait for ACK from. ACK coupling at D _n means that the source node

Must be done while broadcasting from

Is the source node

May be the moment when broadcasting begins.

therefore,

May be defined as in Equation 5.

Likewise,

May be defined as in Equation 6.

In the BTRB scheme, data frames broadcast to D _n are SN _n ,

,

, C _n and U _n , and thus, destinations belonging to D _n may proceed with ACK combining.

< Source and Destination Behavior >

The source node starts broadcasting from beam number n = 0. The source node is an unacknowledged frame (

If present, these unidentified frames may be broadcast.

If the source node has finished broadcasting for D _n , then for the frames previously broadcast by the source node

Since the ACK combining at is complete, the source node switches its beam to (n-1)% N. After that, the source node

Receive a bitmap frame from the last destination in C _{(n-1)% N} in the interval.

Next, the source node

Wait for unicast ACK during the interval. If the bitmap frame and the unicast ACK indicate that the broadcasted frames have been successfully received, the source node may remove those frames from Q _n-1 .

The source node then switches the beam to (n + 1)% N.

When the destination node successfully receives the broadcast data frame, it marks (e.g., "1") the corresponding bit in the bitmap. Each destination may know its ACK combining order or unicast order through a data frame broadcast from the source node.

In the unicast group (ie, destinations designated to perform unicast ACK by the source node), the xth destination node is timed.

ACK can be unicasted to the source node in.

The first destination in an ACK joining group (ie, destinations designated to perform ACK joining by the source node) generates its own bitmap and generates the generated bitmap.

Relays to the next destination in the ACK coupling group.

The last destination in the ACK combining group combines its bitmap with the received bitmap (ie, bitwise AND operation),

Sends the combined bitmap to the source node in.

Destinations other than the first and last destination in the ACK combining group may combine their bitmap with the bitmap received through the relay and relay the combined bitmap to the next destination.

< PERFORMANCE EVALUATION Example >

12 shows an example of comparing reliability based on frame error rate (FER).

13 shows an example of comparing reliability based on frame loss rate (FLR).

The measurement examples of FIGS. 12 to 14 show a data rate of 10 Mbps, a data frame length of 1024 bytes, and an ACK frame length of 2 bytes. In this case, the number of destinations is 60,

Denotes the percentage of the beam table lost assuming an actual communication environment.

In this case, the reliability is a value obtained by dividing the number of transmission success frames by the number of transmission frames including a retransmission frame, and the transmission delay is a value obtained by measuring an average delay from transmission of a data frame to reception of an ACK.

Even through the example of performance measurement, it can be seen that the BTRB technique according to the embodiment of the present invention alleviates the problem of ACK explosion and transmission delay compared to the prior art.

Hereinafter, specific embodiments of the "communication method and communication device using BTBR" will be described based on the principle of BTBR. 11 to 14 may be applied to both the communication method and the description of the communication device to be described later.

The structure shown in FIG. 15 may be the sender S of FIG. 11, that is, the structure of the source node.

Referring to FIG. 15, the source node includes an antenna unit 1510, an antenna switching unit 1520, and a controller 1530.

The antenna unit 1510 broadcasts a data frame using an antenna beam.

The antenna unit 1510 performs i (i is an integer) data frames from a first duration (for example, T _{0 in} FIG. 18) to a first sector (for example, D _{0 in} FIG. 11). Broadcasting is performed to the second sector (D ₁ of FIG. 11) in the second period (for example, T ₁ of FIG. 18).

The antenna unit 1510 receives the collected ACK information of the destination nodes belonging to the first sector after the second period. For example, the antenna unit 1510 may receive ACK information collected from d5 at T _E (0) of T _r2 of FIG. 18. In this case, the aggregated ACK information means "combined bitmap" illustrated in FIG. 16.

The antenna switching unit 1520 switches the antenna beam. That is, the antenna switching unit 1520 performs the antenna beam in the order of D ₀ (beam 0 of S), D ₁ (beam 1 of S), D ₂ (beam 2 of S), and D ₃ (beam 3 of S). Can switch

The antenna switching unit 1520 switches the antenna beam to the second sector after the first section and the reporting section (T _{r1 in} FIG. 18), and switches the antenna beam to the first sector after the second section. .

The controller 1530 generates a beam table (eg, FIG. 11) including beam direction information of each of the destination nodes in communication coverage, and schedules an ACK aggregation order based on the beam table. That is, the controller 1530 performs all the operations described in "< Beam Table-based Reliable Broadcast ( BTBT ) Technique ", "<< ACK Combination >", "< BTRB Protocol >", and "< Source and Destination Behavior >". The operation of the source node can be controlled. Of course, the controller 1530 may include at least one processor designed to control the overall operation of the source node.

In this case, the communication coverage is D ₀ , D ₁ , D ₂ , and D ₃ in the example shown in FIG. 11.

As described in "< Beam Table-Based Reliable Broadcast (BTBT) Scheme >", the controller 1530 may include "information on the beam number from node i to node j" and "node i and node j" during the network setup process. Information about the case in which there is no communication link or that node i does not have information about node j.

In addition, the controller 1530 may be configured to provide information about the beam number from node i to node j and the communication link between node i and node j or node i does not have information about node j. May be used to generate the beam table.

As a simple example, according to the 60 GHz communication technical specification, each node may know the beam number that can communicate with each other through antenna training.

In the example described in Table 1, d ₀ may communicate with S using beam 3 and may transmit a data frame to d ₁ using beam 0. In addition, in the example shown in [Table 1], d ₀ does not have beam information of d ₅ and d ₈ or does not need setting of a communication link, and the beam information is indicated by "-1".

The control unit 1530 uses the beam information (first beam information) for communication of nodes in the first sector and the beam information (second beam information) that interferes with the broadcasting of the second sector. The order of ACK collection for may be determined.

That is, the controller 1530 may perform step 1 to step 3 described in "< ACK Combination >".

The controller 1530 determines a destination for performing an ACK report through unicast according to a communication environment, and inserts information on the destination for performing the ACK report through the unicast into at least one of the i data frames. can do.

That is, the controller 1530 may perform step 4 described in "< ACK Combination >".

The method illustrated in FIG. 16 may be performed by the communication device of FIG. 15, that is, the source node.

In step 1610, the source node generates a beam table including beam direction information of each of the destination nodes in the communication coverage. That is, the source node may generate a beam table as shown in [Table 1] during the network configuration process.

In this case, the beam table includes "information about the beam number from node i to node j" and "information when there is no communication link between node i and node j or node i does not have information about node j". Wherein node i and node j are all nodes within the communication coverage.

In step 11620, the source node schedules an ACK collection order for the first sector of the antenna beam based on the beam table.

That is, the source node, as in steps 1 to 3 of "<ACK Combination >

). In addition, the source node may be configured to perform beam information (second beam information,

) And beam information (third beam information, used for the ACK aggregation using the first beam information and the second beam information

Calculate The source node may determine an ACK aggregation order for the first sector based on the third beam information.

In Figure 11, for the sender S to the broadcast to the D _1, d ₂ when the transmission itself of the bitmap, d ₄ d ₂ of the transmission causes interference to the sender, and D _1. Thus, the source node can use the beam table to determine the order of ACK aggregation that does not cause interference.

In this case, step 11620 may further include determining a destination for performing an ACK report through unicast according to a communication environment, and at least one of the i data frames may be a destination for performing ACK report through the unicast. It may further include information about.

In step 1630, the source node broadcasts i (i is an integer) data frames in the first sector.

In this case, at least one of the i data frames includes ACK aggregation scheduling information generated based on the beam table.

In this case, the ACK aggregation scheduling information includes information on a sector-by-sector multicasting time of the source node, a report time of aggregated ACK information, and a collection order of ACK information.

In step 1640, the source node switches the antenna beam to the second sector, and performs broadcasting in the second sector.

In step 1650, the source node switches the antenna beam to the first sector after the broadcasting of the second sector is completed, and receives the collected ACK information of the destination nodes belonging to the first sector.

In this case, the collected ACK information includes a bitmap indicating whether reception is successful for each of i data frames, and each of the i bits included in the bitmap is each of destination nodes belonging to the first sector. The result of performing an AND operation on whether the i-th data frame is successfully received.

17 shows an example of the configuration of a communication device (destination, or destination node) of a directional wireless communication system according to an embodiment of the present invention.

The structure shown in FIG. 17 may be a structure of each of the destinations of FIG. 11.

Referring to FIG. 17, a receiver includes a receiver 1710, a controller 1720, and an ACK information collector 1730.

The receiver 1710 receives i data frames (i is an integer) multicasted from the first sector of the source node antenna beam. The receiver 1710 may include a directional antenna (not shown) that is switchable for each predetermined sector.

The controller 1720 checks ACK aggregation scheduling information included in at least one of i data frames. The controller 1720 may include at least one processor. In this case, the at least one processor may be configured to control the overall operation of the receiver.

The ACK information collecting unit 1730 collects ACK information for the i data frames based on ACK aggregate or scheduling information.

The ACK information collecting unit 1730 may receive ACK information of a previous receiver belonging to the first sector according to the order included in the ACK collection scheduling information, or may transmit ACK information to the next receiver according to the order.

The ACK information collector 1730 may include a bitmap generator 1731, an AND operator 1733, and a transmitter 1735.

The bitmap generator 1731 generates an "own bitmap" that specifies whether to receive each of the i data frames.

The AND operator 1735 receives the bitmap of the previous receiver and ANDs the bitmap and the magnetic bitmap of the previous receiver. Of course, the AND operator 1733 may receive the bitmap 321 collected from the previous receiver. Here, the bitmap 311 of the previous receiver or the bitmap 321 collected from the previous receiver is received through the antenna of the receiver 1710.

The transmitter 1735 transmits an "aggregated bitmap" reflecting the result of the AND operation to the source node. Of course, the transmitter 1735 may transmit the "aggregated bitmap" reflecting the result of the AND operation to the next receiver.

In FIG. 18, T ₀ and T ₁ represent the broadcasting periods of beam 0 and beam 1, respectively, and T _r1 and T _r2 represent the reporting duration of the collected ACKs.

Referring to FIG. 18, the source node S broadcasts a data frame with D ₀ in a T _{0 period} . After the completion of broadcasting for D ₀ , the source node S switches the beam to ₁ and broadcasts the data frame to D ₁ in the T _{1 period} . ACKs of receivers belonging to D ₀ in the T ₁ interval are collected.

Ts (0) represents a time when d ₄ transmits its bitmap to d ₂ in the scenario of FIG. 11, that is, a start time of ACK combining.

Since there may be a plurality of frames for which an ACK has not been confirmed, the source node S may track and maintain whether an ACK is received for each of the frames.

Each of the receivers maintains a bitmap for the multicast frame. In this case, the bitmap may be used to indicate whether the i-th frame has been successfully received. For example, "1" in the bitmap indicates that the frame has been successfully received. By logically ANDing the bitmaps, the final receiver can know which frame was successfully received for each of all receivers. In this case, the final receiver may be a receiver that collects ACKs and reports them to the source node S. The logical AND operation may be performed in units of bits of the bitmap.

Methods according to an embodiment of the present invention can be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

Claims

In the directional wireless communication system for transmitting and receiving data through the beam of the directional antenna, in the communication method of the receiver,

Receiving i data frames (i is an integer) multicasted in the first sector of the transmitter antenna beam;

Identifying ACK aggregation scheduling information included in at least one of the i data frames; And

Collecting ACK information for the i data frames based on the ACK aggregation scheduling information;

The collection of the ACK information includes receiving ACK information of a previous receiver belonging to the first sector according to an order included in the ACK aggregation scheduling information, or transmitting ACK information to a next receiver according to the order.

Method of communication of a receiver in a directional wireless communication system.
The method of claim 1,

The collection of the ACK information is performed in a section in which the transmitter antenna multicasts to a second sector,

Method of communication of a receiver in a directional wireless communication system.
The method of claim 1,

The ACK aggregation scheduling information,

Including information on the sector-by-sector multicasting time of the transmitter, the reporting time of collected ACK information, and the collection order of ACK information

Method of communication of a receiver in a directional wireless communication system.
The method of claim 1,

The ACK information includes a bitmap that specifies whether to receive each of the i data frames.

Collecting the ACK information,

generating a bitmap indicating whether to receive each of the i data frames; And

Transmitting the bitmap to the next receiver,

Communication method of a receiver in a directional wireless communication system.
The method of claim 1,

The ACK information includes a bitmap that specifies whether to receive each of the i data frames.

Collecting the ACK information,

generating an "own bitmap" specifying whether to receive each of the i data frames;

Receiving a bitmap of the previous receiver; And

And ANDing the bitmap of the previous receiver and the magnetic bitmap;

Communication method of a receiver in a directional wireless communication system.
The method of claim 1,

The ACK information includes a bitmap that specifies whether to receive each of the i data frames.

Collecting the ACK information,

generating an "own bitmap" specifying whether to receive each of the i data frames;

Receiving an aggregated bitmap from the previous receiver;

ANDing the "collected bitmap" and the "magnetic bitmap" received from the previous receiver; And

Transmitting the "collected bitmap" reflecting the result of the AND operation to the transmitter,

Communication method of a receiver in a directional wireless communication system.
The method of claim 5,

The step of transmitting to the transmitter,

Performed after multicasting for the second sector of the transmitter is completed,

Communication method of a receiver in a directional wireless communication system.
A communication apparatus of a directional wireless communication system for transmitting and receiving data through a beam of a directional antenna,

A receiver for receiving i (i is an integer) data frames multicast in the first sector of the transmitter antenna beam;

A control unit which checks ACK aggregation scheduling information included in at least one of the i data frames;

And an ACK information collecting unit for collecting ACK information for the i data frames based on the ACK aggregation scheduling information.

The ACK information collecting unit receives the ACK information of the previous receiver belonging to the first sector according to the order included in the ACK collection scheduling information, or transmits the ACK information to the next receiver in the order,

Communication device in a directional wireless communication system.
The method of claim 8,

The ACK information collecting unit,

a bitmap generator for generating an "own bitmap" that specifies whether to receive each of the i data frames; And

And an AND operator configured to receive a bitmap of the previous receiver and AND the bitmap of the previous receiver and the magnetic bitmap.

Communication device in a directional wireless communication system.
The method of claim 9,

The ACK information collecting unit,

Further comprising a transmitter for transmitting to the transmitter "aggregated bitmap" reflecting the result of the AND operation,

Communication device in a directional wireless communication system.
In a directional wireless communication system for transmitting and receiving data through a beam of a directional antenna, in a sender communication method,

Multicasting i (i is an integer) data frames in a first sector of the antenna beam;

Switching the antenna beam to a second sector and multicasting the i data frames in the second sector; And

Switching the antenna beam to the first sector after completing the multicasting of the second sector, receiving aggregated ACK information of receivers belonging to the first sector,

At least one of the i data frames includes ACK aggregation scheduling information,

Sender communication method in directional wireless communication system.
The method of claim 11,

The ACK aggregation scheduling information,

Including information on the sector-by-sector multicasting time of the transmitter, a reporting time of collected ACK information, and a collection order of ACK information.

Sender communication method in directional wireless communication system.
The method of claim 12,

The collection order of the ACK information,

In the receiver having the largest angle with the sender, the angle with the sender is determined in order of the smallest

Sender communication method in directional wireless communication system.
The method of claim 12,

The collection order of the ACK information,

In the receiver having a shorter distance to the sender is determined in order of the longest distance with the sender,

Sender communication method in directional wireless communication system.
The method of claim 11,

The collected ACK information includes a bitmap indicating whether reception is successful for each of i data frames.

Each of the i bits included in the bitmap is a result of performing an AND operation on reception of an i th data frame of each of the receivers belonging to the first sector.

Sender communication method in directional wireless communication system.
A communication apparatus of a directional wireless communication system for transmitting and receiving data through a beam of a directional antenna,

An antenna unit for multicasting a data frame using an antenna beam;

An antenna switching unit for switching the antenna beam; And

A control unit for generating ACK aggregation scheduling information;

The antenna unit multicasts i (i is an integer) data frames to a first sector in a first duration, performs multicasting to a second sector in a second interval,

The antenna switching unit switches the antenna beam to the second sector after the first period and the reporting period, and switches the antenna beam to the first sector after the second period,

The antenna unit receives the collected ACK information of the receivers belonging to the first sector after the second interval,

Communication device in a directional wireless communication system.
The method of claim 16,

The ACK aggregation scheduling information,

Including information on the sector-by-sector multicasting time of the transmitter, a reporting time of collected ACK information, and a collection order of ACK information.

Communication device in a directional wireless communication system.
The method of claim 17,

The control unit,

Determining a collection order of the ACK information in a receiver having a large angle with the sender in order of a receiver with a small angle with the sender,

Communication device in a directional wireless communication system.
The method of claim 17,

The control unit,

Determining a collection order of the ACK information in a receiver having a short distance from the sender in order of a long distance from the sender;

Communication device in a directional wireless communication system.
The method of claim 16,

The collected ACK information includes a bitmap indicating whether reception is successful for each of i data frames.

Each of the i bits included in the bitmap is a result of performing an AND operation on reception of an i th data frame of each of the receivers belonging to the first sector.

Communication device in a directional wireless communication system.
In the directional wireless communication system for transmitting and receiving data through the beam of the directional antenna, in the communication method of the source node (source node),

Generating, by the source node, a beam table that includes beam direction information of each of the destination nodes in communication coverage;

Scheduling an ACK aggregation order for a first sector of an antenna beam based on the beam table;

Broadcasting i (i is an integer) data frames in the first sector;

Switching the antenna beam to a second sector and performing broadcasting in the second sector; And

Switching the antenna beam to the first sector after completing broadcasting of the second sector, and receiving aggregated ACK information of destination nodes belonging to the first sector,

At least one of the i data frames includes ACK aggregation scheduling information generated based on the beam table;

A method of communication of a source node in a directional wireless communication system.
A communication apparatus of a directional wireless communication system for transmitting and receiving data through a beam of a directional antenna,

An antenna unit for broadcasting a data frame using an antenna beam;

An antenna switching unit for switching the antenna beam; And

A control unit for generating a beam table including beam direction information of each of the destination nodes in communication coverage, and scheduling an ACK collection order based on the beam table;

The antenna unit broadcasts i data frames (i is an integer) to a first sector in a first period and broadcasts to a second sector in a second period.

The antenna switching unit switches the antenna beam to the second sector after the first period and the reporting period, and switches the antenna beam to the first sector after the second period,

The antenna unit receives the collected ACK information of the destination nodes belonging to the first sector after the second interval,

Communication device in a directional wireless communication system.