KR20120062544A - Method and apparatus of transmitting reception acknowledgement in cognitive radio network - Google Patents

Abstract

PURPOSE: A reception confirmation transmission method in a CR(Cognitive Radio) network and apparatus thereof are provided to increase data transmission rates by transmitting a data frame including reception confirmation response information. CONSTITUTION: A transmission and reception apparatus(730) transmits a wireless frame to a target terminal and receives a data frame transmitted by the target terminal. A processor(710) is functionally connected with the transmission and reception apparatus. The processor determines the transmission state of the wireless frame based on reception confirmation information by acquiring the reception confirmation information included in an MAC(Media Access Control) header of the data frame.

Description

TECHNICAL AND APPARATUS OF TRANSMITTING RECEPTION ACKNOWLEDGEMENT IN COGNITIVE RADIO NETWORK}

The present invention relates to wireless communication, and more particularly, to a method for transmitting an acknowledgment in an cognitive wireless network and an apparatus supporting the same.

Rapid development of wireless communication systems and development of various wireless communication services require strict frequency bands in order to solve coexistence problems between existing communication systems. However, due to the allocation of almost all commercially available frequency bands, there is a very shortage of frequency resources for new wireless platforms. Given the current frequency usage, there is little room for sub-GHz bands, especially low frequency bands. In order to solve this problem of frequency shortage, a concept of intelligent radio recognition technology (Cognitive Radio, CR) has been proposed that can detect a frequency band that is allocated but is not actually used but can be effectively shared.

Existing wireless communication systems have strictly controlled the frequency resources in accordance with the frequency policy in the country. Therefore, operators used the frequency resources to be used with approval and allocation from the government. However, unlike the conventional wireless communication system, the intelligent wireless recognition technology is a communication system that uses a frequency resource that is allocated but is not used, without interference to the wireless communication of the existing service provider.

In line with the recent surge in demand for scarce frequency resources, the need for wireless cognitive technologies has emerged, and in December 2003, the use of frequency commons in the Notice of Proposed Rule Making (NPRM) of the Federal Communications Commission (FCC) in the United States. Since the possibility is mentioned, much interest and research on intelligent wireless recognition technology has been conducted. As a representative example, IEEE 802.22 Wireless Regional Area Networks (WRAN) standardization is being performed to develop a communication platform using intelligent wireless recognition technology. The target audience for IEEE 802.22 WRAN is in the outskirts of the United States or Canada, or in developing countries, with the goal of providing wireless communications services using intelligent wireless communications technology in unused TV bands.

As mentioned above, although standardization and development of radio recognition technology are being activated, there are many problems to be solved because it is still in an early stage, and most configuration technologies have not been determined yet.

A cognitive radio terminal operating in a cognitive radio communication system uses an unlicensed band shared with other communication systems. Therefore, in addition to the general noise present in the wireless communication system, it should be assumed that interference by other communication systems also exists and interferes with the communication.

Due to the nature of such an environment, when a radio frame is transmitted, it is necessary to confirm whether the radio frame is normally delivered to the target terminal, that is, the target terminal normally receives the radio frame.

The procedure of confirming whether the target terminal has normally received the radio frame may be performed by the transmitting terminal transmitting the radio frame and receiving an acknowledgment response from the target terminal receiving the radio frame. However, receiving an acknowledgment response corresponding to a transmitting radio frame means that a corresponding channel cannot be used for data transmission during a period required for transmitting a frame for transmitting an acknowledgment response, which is a side of efficient use of radio resources. May be undesirable in In order to solve this problem, it is necessary to consider a method of transmitting an acknowledgment message and an apparatus supporting the same.

An object of the present invention is to provide an acknowledgment transmission method and apparatus in a cognitive wireless network that can increase the amount of data transmission in the entire network by reducing the frame overhead due to acknowledgment transmission.

In one aspect of the present invention, an acknowledgment transmission method in a wireless network includes a data frame including at least one radio frame and acknowledgment response information indicating whether the at least one radio frame is normally received. It includes sending.

The acknowledgment response information may be transmitted in an acknowledgment field included in a MAC header of the data frame.

The acknowledgment field may have a length of 1 bit and may indicate ACK or NACK.

The acknowledgment response information may be transmitted in a piggyback block ACK field indicating whether a plurality of radio frames have been normally received, and the piggyback block ACK field is transmitted between a MAC header and a MAC payload of the data field. Can be.

The MAC header of the data frame may further include a piggyback block ACK field indicating whether the piggyback block ACK field is included in the data frame.

The piggyback block ACK field may have a length of 1 bit.

The piggyback block ACK field may include a BA subfield including ACK / NACK information for each of the plurality of radio frames, and a size subfield indicating the length of the BA subfield.

In another aspect of the present invention, an acknowledgment method performed by a transmitting terminal in a cognitive wireless network transmits at least one radio frame to a target terminal, and receives or overhears a data frame transmitted by the target terminal. overhearing) to obtain acknowledgment response information included in the MAC header of the data frame, determine whether the at least one radio frame is normally transmitted to the target terminal based on the acknowledgment response information, and And determining whether to retransmit one radio frame to the target terminal.

The acknowledgment response information may be transmitted by the destination terminal in an acknowledgment field included in a MAC header of the data frame.

The acknowledgment response information is transmitted by the target terminal in a piggyback block ACK field indicating whether the target terminal has normally received a plurality of radio frames, and the piggyback block ACK field is a MAC header of the data field. And between the MAC payload.

The MAC header of the data frame may further include a piggyback block ACK field indicating whether the piggyback block ACK field is included in the data frame.

The piggyback block ACK field may include a BA subfield including ACK / NACK information for each of the plurality of radio frames, and a size subfield indicating the length of the BA subfield.

The transmitting terminal compares a receiver address of the at least one radio frame with a sender address of the data frame transmitted by the target terminal, so that the acknowledgment response information included in the data frame is determined for the at least one radio frame. The method may further include determining whether the response is an acknowledgment response.

In another aspect of the present invention, a terminal supporting an acknowledgment transmission method in a wireless network according to the present invention receives a at least one radio frame and is functionally connected with the transceiver and the transceiver configured to transmit a data frame. And a processor configured to transmit the data frame by including acknowledgment response information indicating whether the at least one radio frame is normally received in the data frame.

In another aspect of the present invention, a terminal supporting an acknowledgment method in a wireless network according to the present invention transmits at least one radio frame to a target terminal, and receives or overhears a data frame transmitted by the target terminal. and a processor configured to be overhearing and a processor functionally connected to the transceiver, wherein the processor acquires acknowledgment response information included in a MAC header of the data frame and based on the acknowledgment response information. Determine whether or not the radio frame of the Tx terminal is normally transmitted to the target terminal, and determine whether to retransmit the at least one radio frame to the target terminal.

In cognitive radio networks, overhead due to acknowledgment transmission can be minimized, and competition overhead can also be reduced. As a result of the reduction in overhead, the data rate can be increased.

1 illustrates an example of transmitting an imm-ACK frame in response to a transmission of a radio frame and an acknowledgment response thereto.
2 is a block diagram schematically illustrating a frame structure supporting a method of transmitting an acknowledgment response according to an embodiment of the present invention.
3 is a block diagram showing a structure of a radio frame for transmitting an acknowledgment response according to another embodiment of the present invention.
4 illustrates an example of a method for transmitting an acknowledgment response according to an embodiment of the present invention.
5 illustrates another example of a method for transmitting an acknowledgment response according to an embodiment of the present invention.
6 shows another example of a method for transmitting an acknowledgment response according to an embodiment of the present invention.
7 is a block diagram illustrating a terminal that can implement various embodiments of the present invention.

In the ECMA 392 standard, an acknowledgment protocol is used for the reliable transmission of frames. The acknowledgment protocol operates in three strategies as necessary, and can be classified into imm-ACK, block-ACK, and No ACK policies, respectively. Each retransmission policy is performed at the MAC layer, but the retransmission policy may be determined according to characteristics of higher protocols or applications, categories or characteristics of data to be transmitted, and the like.

The No ACK policy does not transmit an ACK frame when a data frame is received at the MAC layer. This method is selected for voice calls or transmission of real-time video data frames that do not need to receive an ACK. Since these real-time data frames do not perform flow control at higher layers, there is no need to retransmit frame loss.

Next, when a normal frame is received, there is a policy using imm-ACK indicating that frame reception is normally completed. Data frames for which this policy can be used include control frames, picture or video data frames, which are not sensitive to delays in transmission time, but sensitive to transmission losses. imm-ACK frame is transmitted with only header information of frame, so transmission overhead is large.

1 illustrates an example of transmitting an imm-ACK frame in response to a transmission of a radio frame and an acknowledgment response thereto.

In the example of FIG. 1, terminal A 10 transmits MAC frame 1 110 to terminal B 20. Assuming a case of the imm-ACK policy, the terminal B 20 receiving the MAC frame 1 110 transmits the imm-ACK frame 1 115 to the terminal A 10 for acknowledgment. When the terminal B 20 normally receives the MAC frame 1 110, it transmits a positive acknowledgment ACK, and when the terminal B 20 does not normally receive the MAC frame 1 110, a negative acknowledgment NACK. If the terminal B 20 transmits a NACK to the terminal A 10, this means that the terminal B 20 has not normally received the MAC frame 1 (110) transmitted by the terminal A (10) terminal The A 10 may retransmit the MAC frame 1 110 to the terminal B 20.

In the example of FIG. 1, the terminal A 10 receiving the ACK for the transmission of the MAC frame 1 110 then transmits the MAC frame 2 120 and the MAC frame 3 130, and the terminal B 20 sends the MAC frame. An imm-ACK frame 2 125 is transmitted as an acknowledgment for transmitting 2 (120), and an imm-ACK frame 1 135 is transmitted as an acknowledgment for transmitting the MAC frame 3 (130).

1 illustrates an imm-ACK frame transmission method in a contention-based wireless communication system. The SIFS, AIFS, and backoff process of FIG. 1 are based on a contention-based wireless communication system (eg, IEEE 802.11). FIG. 1 illustrates an example of a backoff window for avoiding an interframe space and a collision that manages access to a transmission medium in a WLAN system.

Referring to FIG. 1, it can be seen that a PHY preamble is added to a MAC header to transmit imm-ACK 1 115, imm-ACK 2 125, and imm-ACK 3 135 frames. Since the PHY preamble is generated every time a radio frame is transmitted to transmit the MAC frame wirelessly, an overhead for transmitting an imm-ACK frame for notifying only normal acknowledgment of the frame is increased.

When the cognitive radio system uses the TV white space frequency domain, the PHY side transmission overhead for the PHY preamble is also large. In addition, in a contention-based wireless communication system, if an imm-ACK frame does not arrive, transmission must be transmitted again through contention (for example, a backoff process in the example of FIG. 1), and there is an overhead due to contention.

The overhead due to contention varies with AIFS time and backoff time, as can be seen in the example of FIG. If a collision occurs during the competition, the backoff window is increased, resulting in greater competition overhead. Therefore, if the overhead for imm-ACK frame transmission described above is reduced, network efficiency can be improved.

The ECMA standard and the IEEE 802.11e standard support a block ACK (block-ACK, BA) scheme to minimize the overhead of such an imm-ACK frame. A block ACK frame is a frame in which a receiving terminal collects ACK information for received data frames after receiving previously promised data frames, instead of immediately receiving an ACK response whenever a data frame transmitted by the transmitting terminal arrives.

However, the block ACK frame itself may not only have a small payload but also may not be able to set the block ACK due to the situation of the receiver. In this case, imm-ACK frame should be transmitted every frame.

The payload of the data frame is up to 4000 bytes or more in size. However, although the upper layer of MAC layer is not defined, TCP / IP layer is used for interworking with external internet network. In this case, since the maximum size of the frame provided by the external Ethernet is 1500 bytes, the payload constituting the data frame is composed of a combination of one or more IP packets. So if you have information to piggyback in a data frame, you can easily add it when constructing the payload.

Therefore, in order to effectively perform automatic repeat request (ARQ) policies, including acknowledgment and retransmission of data transmitted over cognitive radio networks that support the ECMA standard, implicit ARQ policies and piggyback functions as well as explicit ARQ policies Can be used.

2 is a block diagram schematically illustrating a frame structure supporting a method of transmitting an acknowledgment response according to an embodiment of the present invention.

The radio frame 200 according to the embodiment of the present invention includes a MAC header 210 and a MAC payload 220 including data to be transmitted. The MAC header 210 may include a frame control field, an address field, a sequence control field, and the like that contain control information of a frame. The radio frame 200 according to an embodiment of the present invention may further include an acknowledgment field indicating whether or not data is normally received in the MAC header 210. The acknowledgment field may have a length of 1 bit, and one bit may indicate an ACK / NACK or success / fail state indicating whether data reception is successful. In FIG. 2, the ACK / NACK bit 215 illustrates an example. The ACK / NACK bit 215 of FIG. 2 may use a reserved bit area in which use of a frame control field included in the MAC header 210 is reserved. In the example of FIG. 2, since only the bit information for expressing the success or failure of the data transmission (ACK / NACK) is defined, the ACK / NACK bit 215 is not added to the payload 220.

If the radio frame is normally received, the ACK / NACK bit 215 can be set to ACK (for example, 0). If the radio frame is not normally received, the ACK / NACK bit 215 can be set to NACK (for example, 1). have.

In order to check whether the imm-ACK or imm-NACK information included in the received data frame is a response to the frame sent by the transmitting terminal, the receiving device of the data frame receiving and transmitting the previous imm-ACK is received. Determine / compare whether the data frame is a transmitting terminal.

That is, after the transmitting terminal transmits the data frame to the receiving terminal, if the destination address of the next received data frame matches the destination address of the previous data frame and the imm-ACK bit is set, It may be determined that a normal imm-ACK frame is received.

3 is a block diagram showing a structure of a radio frame for transmitting an acknowledgment response according to another embodiment of the present invention.

The radio frame 300 for transmitting an acknowledgment response according to another embodiment of the present invention includes a MAC header 310 and a MAC payload 330. Here, the functions of the MAC header 310 and the MAC payload 330 are the same as those of the MAC header 210 and the MAC payload 220 of FIG. 2.

Piggyback BA setting indicating whether the radio frame 300 according to an embodiment of the present invention includes a piggyback block ACK field 320 indicating whether or not a plurality of data frames are normally received in the MAC header 310 It may further include a field 315. The piggyback BA setting field 315 may have a length of 1 bit. The piggyback BA setting field 315 may use a reserved bit area in which use of the frame control field included in the MAC header 310 is reserved. In the example of FIG. 3, since the piggyback BA setting field 315 has only bit information for expressing success or failure of data transmission (ACK / NACK), nothing is added to the payload 330.

When the piggyback BA setting field 315 indicates that the piggyback block ACK field 320 is included in the radio frame 300, the radio frame 300 includes a piggyback block ACK field 330. The piggyback block ACK field 320 includes a size subfield 324 for indicating the size of the piggybacked block ACK frame and a BA subfield 327 indicating whether each of the plurality of data frames is normally received. . The piggyback block ACK field 320 may be transmitted between the MAC header 310 and the MAC payload 330.

4 illustrates an example of a method for transmitting an acknowledgment response according to an embodiment of the present invention.

The MAC frame and the data frame of FIG. 4 may use the frame format of FIG. 2. In other words, the ACK / NACK bits may be included in the MAC header of the frame. After the terminal B 20 receives the MAC frame 1 410 from the terminal A 10, imm-ACK information is added to the data frame 415 to be transmitted to the terminal A 10. The terminal A 10 checks the imm-ACK bit for the MAC frame 1 410 previously transmitted from the data frame 415 received from the terminal B 20 and receives the received frame in the next frame MAC frame 2 420. The imm-ACK bit for data frame 1 (415) is set and transmitted. Similarly, data frame 2 425 and MAC frame 3 430 may be transmitted.

If the terminal receiving the data frame does not have a data frame to transmit to the terminal that has transmitted the data frame, it can just generate and transmit an imm-ACK frame. In the example of FIG. 4, the Imm-ACK frame 3 435 transmitted by the terminal B 20 to the terminal A 10 is an example.

In the example of FIG. 4, if there is an error in the received data frame, the imm-NACK bit may be set and transmitted. In this case, when the transmitting terminal receives the frame in which the imm-NACK bit is set, the transmitting terminal may retransmit the previous data frame. Alternatively, if imm-ACK or imm-NACK information for a transmitted frame is not received within a specified time, transmission of the previous data frame may be considered as failed and the previous data frame may be retransmitted (when necessary to access the medium through competition). have.

5 illustrates another example of a method for transmitting an acknowledgment response according to an embodiment of the present invention.

Figure 5 shows an example of transmitting and receiving imm-ACK information according to an embodiment of the present invention when three or more terminals transmit / receive data frames. First, the terminal A 10 transmits the MAC frame B1 510 to the terminal B 20. In this case, it is assumed that the terminal B 20 has a frame to be transmitted to the terminal C 30, not a frame to be transmitted to the terminal A 10. In this case, the terminal B 20 sets imm-ACK bits in the MAC frame C1 520 transmitted to the terminal C 30 and transmits them.

In this case, the terminal A 10 also receives the MAC frame C1 520 transmitted by the terminal B 20. If the destination of the received MAC frame C1 520 is not itself, but the imm-ACK bit is set, the terminal A 10 sends a MAC frame that is the frame previously transmitted by the source of the received MAC frame C1 520. Check whether the terminal B 20 corresponds to the destination B1 510. In the example of FIG. 5, the terminal A 10 has previously matched with the source B of the received MAC frame C1 520 and the terminal B 20, which is the destination of the MAC frame B1 510, which is a frame previously transmitted. It is determined that imm-ACK information about the transmitted frame MAC frame B1 510 is received.

The terminal C 30 receives the MAC frame C1 520 from the terminal B 20 and sets and transmits an imm-ACK bit in the data frame MAC frame A1 530 to be transmitted immediately.

In the imm-ACK transmission method, the terminal B 20 and the terminal C 30 may transmit the data frame after transmitting the imm-ACK frame for the received data frame, but the proposed transmission method of the present invention According to the present invention, the overhead of the imm-ACK frame transmission can be reduced by including the imm-ACK bit in the data frame to be transmitted. In addition, since the terminal receiving the data frame continues to transmit with only a minimum time delay (for example, short interframe space (SIFS) as shown in the example of FIG. 5), the overhead due to contention can be reduced.

Thus, instead of explicitly transmitting the imm-ACK frame, the imm-ACK is determined based on the imm-ACK bit information and the address of the transmitting terminal. Therefore, the implicit imm-ACK / It can be called a NACK transmission method.

6 shows another example of a method for transmitting an acknowledgment response according to an embodiment of the present invention.

In the example of FIG. 6, a block ACK request is received from the terminal A 10, and a plurality of data frame MAC frame block 1 610-1, MAC frame block 2 610-2, MAC frame block 3 610-3, and Data frame MAC frame 615 to which the terminal B 20 receiving the MAC frame block 4 610-4 must transmit a block ACK including the respective ACK / NACK information for the plurality of data frame blocks received by the terminal B 20. Piggyback and send to).

The piggybacked block ACK is also determined using the information of the piggyback BA configuration field of the received data frame and the address of the transmitting terminal in the same manner as the implicit imm-ACK / NACK scheme described with reference to the example of FIG. 5. Of course, if there is no data frame (MAC frame 615 in the example of FIG. 6) to be transmitted by the terminal that needs to transmit the imm-ACK or block ACK, the imm-ACK or block-ACK frame may be generated and transmitted.

7 is a block diagram illustrating a terminal that can implement various embodiments of the present invention.

The terminal 700 includes a processor 710, a memory 720, and a transceiver 730. The transceiver 730 is set to transmit / receive a radio frame. The processor 710 is operatively connected to the transceiver 730, and is configured to generate a radio frame according to the frame format described above and transmit the generated frame through the transceiver 730. The terminal 700 may operate as a terminal of an IEEE 802.11 station or a cognitive radio communication supporting the ECMA 392 standard according to a wireless communication protocol and setting implemented in the processor 710.

Processor 710 and / or transceiver 730 may include an application-specific integrated circuit (ASIC), other chipset, logic circuit, and / or data processing device. The memory 720 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage device. When the embodiment is implemented in software, the above-described techniques may be implemented with modules (processes, functions, and so on) that perform the functions described above. The module may be stored in the memory 720 and executed by the processor 710. The memory 720 may be inside or outside the processor 710 and may be connected to the processor 710 by various well-known means.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (15)

In the acknowledgment wireless network transmission method,
Receive at least one radio frame, and
And transmitting a data frame including acknowledgment response information indicating whether the at least one radio frame is normally received. The method according to claim 1,
The acknowledgment response information is transmitted in an acknowledgment field included in a MAC header of the data frame. The method of claim 2,
The acknowledgment field has a length of 1 bit and indicates an ACK or a NACK. The method according to claim 1,
The acknowledgment response information is transmitted in a piggyback block ACK field indicating whether a plurality of radio frames have been normally received.
The piggyback block ACK field is transmitted between a MAC header and a MAC payload of the data field. The method of claim 4, wherein
The MAC header of the data frame further includes a piggyback block ACK field indicating whether the piggyback block ACK field is included in the data frame. The method of claim 5,
The piggyback block ACK field has a length of 1 bit. The method of claim 4, wherein
The piggyback block ACK field includes a BA subfield including ACK / NACK information for each of the plurality of radio frames;
And a size subfield indicating the length of the BA subfield. In the acknowledgment method performed by a transmitting terminal in a cognitive radio network,
Transmit at least one radio frame to the destination terminal,
Receive or overhear the data frame transmitted by the target terminal to obtain acknowledgment response information included in the MAC header of the data frame,
Determining whether the at least one radio frame is normally transmitted to the target terminal based on the acknowledgment response information, and
Determining whether to retransmit the at least one radio frame to the destination terminal. The method of claim 8,
The acknowledgment response information is transmitted by the destination terminal in an acknowledgment field included in a MAC header of the data frame. The method of claim 8,
The acknowledgment response information is transmitted by the target terminal in a piggyback block ACK field indicating whether the target terminal has normally received a plurality of radio frames,
The piggyback block ACK field is transmitted between a MAC header and a MAC payload of the data field. The method of claim 10,
The MAC header of the data frame further includes a piggyback block ACK field indicating whether the piggyback block ACK field is included in the data frame. The method of claim 10,
The piggyback block ACK field includes a BA subfield including ACK / NACK information for each of the plurality of radio frames;
And a size subfield indicating the length of the BA subfield. The method of claim 8,
The transmitting terminal compares a receiver address of the at least one radio frame with a sender address of the data frame transmitted by the target terminal, so that the acknowledgment response information included in the data frame is determined for the at least one radio frame. Determining whether the response is an acknowledgment. A transceiver configured to receive at least one radio frame and to transmit a data frame; And
And a processor operatively connected to the transceiver and configured to transmit the data frame by including acknowledgment response information indicating whether the at least one radio frame is normally received in the data frame. A transceiver configured to transmit at least one radio frame to a target terminal, and to receive or overhear a data frame transmitted by the target terminal; And
Including; processor functionally connected with the transceiver;
The processor obtains acknowledgment response information included in a MAC header of the data frame,
Determining whether the at least one radio frame is normally transmitted to the target terminal based on the acknowledgment response information, and
And determine whether to retransmit the at least one radio frame to the destination terminal.

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