KR100981491B1 - Apparatus and method for transmitthing ack/nack signal to forward link by using h-arq in a mobile communication system - Google Patents

Abstract

end. The technical field to which the invention described in the claims belongs

The present invention relates to an apparatus and method for transmitting a forward response signal in a mobile communication system, and more particularly, to an apparatus and method for transmitting a forward response signal transmitted by a hybrid automatic retransmission (H-ARQ) method.

I. The technical problem to be solved by the invention

The present invention can maximize the throughput of the forward link in the mobile communication system of the H-ARQ method, the response signal transmission apparatus and method that can reduce the overhead of the system, reduce the error of the response signal, and improve the power efficiency of the response signal To provide.

All. Summary of Solution of the Invention

An apparatus according to an embodiment of the present invention is a device for transmitting a forward response signal in a mobile communication system that transmits only a response signal in a complex automatic retransmission scheme, and counts the number of times of transmission of the received physical layer packet, and calculates the counted value. A counter to output, a signal point mapper to map and output a response signal according to the mapping control signal, and when the received physical layer packet is the first packet, the mapping of the response signal is controlled in a unipolar manner, and the first and subsequent packets And a controller for controlling the mapping of the response signal in a bipolar manner if it is not the last packet, and outputting a mapping control signal to gate off the signal point mapper for the last packet.

la. Important uses of the invention

It is used to transmit forward response signal in H-ARQ type mobile communication system.

H-ARQ, forward response signal, ACK / NAK, ACK-CH.

Description

Apparatus and method for forward response signal transmission using complex automatic retransmission in mobile communication system {APPARATUS AND METHOD FOR TRANSMITTHING ACK / NACK SIGNAL TO FORWARD LINK BY USING H-ARQ IN A MOBILE COMMUNICATION SYSTEM}             

1 is a block diagram of a signaling mapping apparatus for transmitting only a response signal according to the present invention;

2 is a block diagram illustrating a signaling mapping apparatus for simultaneously transmitting a response signal and a scheduling signal according to another embodiment of the present invention.

The present invention relates to an apparatus and method for transmitting a forward response signal in a mobile communication system, and more particularly, to an apparatus and method for transmitting a forward response signal transmitted by a hybrid automatic retransmission (H-ARQ) method.

In general, a response signal is generated and transmitted as a method for identifying a reception state of data transmitted from a mobile communication system. These response signals are divided into forward and reverse directions according to the transmission direction. The forward direction is the direction from the base station to the mobile terminal, and the reverse direction is the direction from the mobile terminal to the base station.

Meanwhile, in order to increase throughput of a reverse link in a wireless packet mobile communication system supporting multimedia services, it is essential to use a hybrid automatic repeat reQuest (hereinafter referred to as "H-ARQ") technology. Here, the H-ARQ is an H-ARQ for a physical layer packet (PLP). A case in which a frame is transmitted in the reverse direction by the H-ARQ method will be described below. The base station notifies the physical layer packet transmitted from the mobile station whether the physical layer packet is successfully received through an acknowledgment channel (ACK-CH) of the forward link. That is, when a physical layer packet is successfully received, an ACK signal is transmitted through the response channel, and when the reception of the physical layer packet fails, a NAK signal is transmitted through the response channel. In this way, the mobile station transmits a new packet or retransmits a previously transmitted packet according to the signal received through the response channel. That is, the mobile station receiving the ACK signal through the response channel transmits a new packet, and the mobile station receiving the NAK signal through the response channel retransmits the previously transmitted packet. Accordingly, when the decoding fails for the previously received packet, the base station may attempt to decode the packet transmitted together with the retransmitted packet and the previously received packet, thereby increasing the probability of success of the packet.

On the other hand, the base station should give a response to the ACK signal or NAK signal through the response channel at the same time to the packets received from the plurality of mobile terminals. Therefore, the response signals transmitted from the base station to the mobile station are transmitted by time division (TDM) or code division (CDM).

However, as described above, the power required to transmit the response signals transmitted from the base station to the plurality of mobile terminals reduces power allocated to the data channel of the forward link. This results in reduced throughput of the forward link. Thus, a technique is needed to reduce the power overhead of the response channel in order not to reduce the throughput of the forward link.

Accordingly, an object of the present invention is to provide an apparatus and method for transmitting a response signal capable of maximizing a throughput of a forward link in an H-ARQ type mobile communication system.

Another object of the present invention is to provide an apparatus and method for transmitting a response signal capable of reducing an overhead in an H-ARQ mobile communication system.

Still another object of the present invention is to provide an apparatus and method for transmitting a response signal capable of reducing an error of a response signal transmitted in a forward direction in a H-ARQ mobile communication system.

It is still another object of the present invention to provide an apparatus and method for transmitting a response signal capable of increasing power efficiency of a response signal transmitted in a forward direction in a mobile communication system using an H-ARQ scheme.

An apparatus according to an embodiment of the present invention for achieving the above object is a device for transmitting a forward response signal in a mobile communication system transmitting only a response signal in a complex automatic retransmission scheme, the number of transmission of the received physical layer packet is counted And a counter for outputting the counted value, a signal point mapper for mapping and outputting a response signal according to a mapping control signal, and mapping the response signal in a unipolar manner when the received physical layer packet is the first packet. And a controller for controlling the mapping of the response signal in a bipolar manner if it is not the last packet, and outputting a mapping control signal to gate off the signal point mapper for the last packet.

In accordance with another aspect of the present invention, an apparatus for transmitting a forward response signal in a mobile communication system that simultaneously transmits a response signal and scheduling information in a complex automatic retransmission scheme may include: A counter for counting the number of transmissions and outputting the counted value, a signal point mapper for mapping and outputting a response signal according to a mapping control signal, and if the received physical layer packet is not the last packet, reception is good or reception is bad. And a controller for controlling to transmit information of reception goodness and channel resource maintenance, and outputting a mapping control signal to indicate only whether the channel resource is maintained for the last packet.

In addition, the devices according to the above embodiments are controlled with different channel gain control values according to the number of transmission of the physical layer packet.

A method according to an embodiment of the present invention for achieving the above object is a method of transmitting a forward response signal to the physical layer packet received in the reverse direction in a mobile communication system transmitting only a response signal in a complex automatic retransmission method, If the received physical layer packet is the first packet, controlling the mapping of the response signal in a unipolar manner; and if the received physical layer packet is after the first and not the last packet, mapping the response signal in the bipolar manner And controlling to gate off the signal point mapper when the received physical layer packet is the last packet.

A method according to another embodiment of the present invention for achieving the above object, as a method of transmitting a forward response signal for the physical layer packet received in the reverse direction in a mobile communication system for transmitting a response and scheduling information together in a compound automatic retransmission method When the received physical layer packet is not the last packet, transmitting information of reception good, poor reception, reception good, and channel resource retention; and if the received physical layer packet is the last packet, whether to maintain the channel resource. And transmitting the information indicating only.

In addition, the methods according to the above embodiments are controlled with different channel gain control values according to the number of transmission of the physical layer packet.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings.

In addition, in the following description, there are many specific details such as specific messages or signals, which are provided to aid the overall understanding of the present invention, and it is understood that the present invention may be practiced without these specific details. It will be self-evident to those of ordinary knowledge. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In general, the ACK bit is represented by '0' and the NAK bit is represented by '1' or vice versa. As described above, when the ACK / NAK bit of the response channel is displayed, the ACK / NAK bit goes through a signal point mapping process for transmission through the wireless channel in the mobile communication system. For example, 0 (ACK) maps to '+1' and 1 (NAK) maps to '-1'. In other words, the digital signal is mapped to a +1 and -1 bipolar signal. As such, using a bipolar signal (+ 1 / -1) increases the power efficiency of a digital signal than using a unipolar signal (+1/0 or 0 / -1). do. However, since the ACK bit or the NAK bit may not have the same probability of occurrence unlike a general digital signal, a design of power efficient signal point mapping is necessary. Therefore, the present invention is configured to include the step of mapping the signal point of the response channel in a power efficient in consideration of the probability of occurrence of the ACK / NAK bits.

In addition, the present invention considers the gate-off of the response channel during discontinuous transmission (DTX) including a period in which no data is transmitted, and in response to the last retransmission when the limited number of retransmissions is used. Considering this, we design a power efficient ACK channel.

In general, two response channels may be used. In the first method, only ACK / NAK for H-ARQ is transmitted. In the second method, the ACK / NAK for the H-ARQ is transmitted and the scheduling information is transmitted at the same time. In the present invention, the above two methods will be described in contrast to the prior art and the present invention.

1. In case of transmitting only ACK / NAK in H-ARQ method

First, a method of transmitting only ACK / NAK in the currently used H-ARQ scheme will be described. As described above, the ACK bit is represented by 0 and the NAK bit is represented by 1. These ACK / NAK bits go through signal point mapping. Therefore, 0 (ACK) is mapped to '+1' and 1 (NAK) is mapped to '-1'. That is, mapping to bipolar signals of +1 and -1 is common. This is because using a bipolar signal (+ 1 / -1) is generally more power efficient than using a unipolar signal (+1/0 or 0 / -1).

On the other hand, H-ARQ usually has a fixed number of retransmissions. In this description, it is assumed that a packet is transmitted up to three times for convenience. That is, when initial transmission fails, two retransmissions are possible. In the following description, initial transmission is described as a first packet, a first retransmission as a second packet, and a third packet for the last retransmission. When the base station receives a packet in the H-ARQ scheme, the base station transmits ACK / NAK through + 1 / -1 bipolar signaling for the first packet, the second packet, and the third packet.

As such, transmitting the first, second and third packets through bipolar signaling has the following problem.

First, when the first packet is transmitted through bipolar signaling, there are two problems described below.

First, the base station does not transmit the ACK / NAK bit for the mobile station in the response channel when the mobile station does not transmit data, that is, to prevent waste of the transmission power in the discontinuous transmission (DTX) interval. That is, the device that performs the ACK / NAK response to the corresponding mobile terminal is gated off (gate off). By gate off in this manner, power is not allocated to the response to the mobile station. When the mobile station in the discontinuous transmission period starts to transmit data, the base station gates on a device that performs the corresponding ACK / NAK response, and performs an ACK / NAK response of + 1 / -1. . However, if the mobile station starts to transmit data and the base station fails to detect this, the base station still gates the device that performs the ACK / NAK response to the corresponding mobile station of the ACK channel. Will be maintained. Thus, the base station has not transmitted any signal. However, since the mobile station is in a state of transmitting data, the ACK / NAK is determined by using the received "0 (no signal received)" signal even though no signal is received from the base station.

At this time, the mobile station does not have any problem because the mobile station retransmits if the result of the received signal is NAK. However, if the mobile station determines ACK, the mobile station transmits a new packet, thereby increasing the packet error rate. That is, when the base station does not detect the existence of the packet for the initial transmission after the discontinuous transmission, the mobile station has a high probability of determining that the response that has been gated off is ACK, and the packet is lost. Bring it.

Second, in general, the first packet is a packet having a high probability of transmission failure. According to the experimental results according to the success probability of the packets in each order, the probability of success of the first packet is 10%, the probability of success of the second packet is 60-70%, and the probability of success of the third packet is more than 90%. . That is, the base station has a 90% probability of transmitting the NAK for the first packet. In this case, if ACK / NAK is transmitted through bipolar signaling (+ 1 / -1), there is a problem in that power efficiency used for a response channel is actually lowered.

Accordingly, in the present invention, in order to solve the above two problems, the first packet is mapped to NAK (1) '0' and the ACK (0) is mapped to '+1'. This can solve the first problem. That is, when the mobile station performs data transmission and the base station does not detect this, the base station is in a state of gate-off ('0') the corresponding response channel. Even in this case, the mobile station can prevent the packet from being lost by allowing the mobile station to recognize that the NAK signal has been received for the first packet as described above.

In addition, by mapping the NAK signal of the first packet as described above, it is possible to minimize the power used in the response channel by gate-off the response channel during the NAK transmission for the first packet that is likely to fail. That is, the use of unipolar signaling consumes more power than the use of bipolar signaling. However, if the probability of occurrence of NAK is greater than 75%, power consumption is reduced because the NAK signal is mapped to '0'.

That is, when bipolar signaling, ACK / NAK is mapped to -1 / 1,

With unipolar signaling, map ACK / NAK to 2/0 (keep the distance between the two mapping points equal to 2 for bipolar-like performance)

P (ACK): Probability of ACK, P (NAK): Probability of NAK

이고,

이다. 따라서 유니폴라가 2배 더 많은 전력를 사용한다.If ACK and NAK are equally likely, then P (ACK) = P (NAK) = 1/2

ego,

to be. So unipolar uses twice as much power.

이고,

이다. 따라서 유니폴라와 바이폴라가 같은 전력을 사용한다. 만약 NAK의 발생할 확률이 3/4보다 크면, 유니폴라가 바이폴라보다 더 적은 전력을 사용할 수 있게 된다. However, if the probability that NAK occurs is 3/4 and ACK is 1/4, then P (ACK) = 1/4 and P (NAK) = 3/4

ego,

to be. Thus unipolar and bipolar use the same power. If the probability of occurrence of a NAK is greater than three quarters, then unipolar will be able to use less power than bipolar.

The same can be said for the opposite case. That is, even when the probability of generating ACK is relatively higher than the probability of generating NAK, if a signal having a high probability of occurrence is mapped to a signal point '0', the transmission power can be efficiently used.

Next, the third packet will be described. After transmitting the third packet, the mobile station transmits a new packet regardless of whether the packet failed or succeeded. That is, if the third packet fails to transmit, no further retransmission can be performed. Therefore, the base station does not need to generate an ACK signal or a NAK signal and inform the mobile station. This is because even if this information is not informed, there is no problem in operation. However, the current H-ARQ scheme is configured to transmit ACK / NAK identically without distinguishing initial transmission, first retransmission and last transmission. This causes unnecessary power waste in the response channel.

Therefore, the present invention minimizes the power used for the response channel by gateing off the ACK channel for the last transmission (third packet).

2. In case of transmitting ACK / NAK including scheduling in H-ARQ scheme

The scheduling information indicates whether the mobile station may continuously send a packet that occupies the same amount of resources as the packet transmitted after receiving the ACK. In this case, three pieces of information are transmitted using the ACK channel such as good reception / bad reception / good reception and packet maintenance (ACK / NAK / ACK and continue). Three pieces of information are signal mapped to + 1/0 / -1, respectively.                     

In the technology currently used, the base station transmits ACK / NAK / ACK and continue through signaling of + 1/0 / -1 for the first packet, the second packet, and the third packet. As mentioned in 1 above, there is no problem in the operation of the mobile terminal even when the base station does not transmit information on the ACK or NAK when transmitting the last packet. However, in the current system, power consumption is large by signaling + 1/0 / -1 for the first packet, the second packet, and the third packet. Therefore, the present invention transmits only continue / not continue, which transmits only scheduling information, when transmitting the ACK channel of the last third packet. Thus, power consumption can be reduced by bipolar signaling of + 1 / -1. In addition, when the last packet is NAK, there is an advantage of increasing the degree of freedom of scheduling by sending continue information.

Next, a case in which data of a response channel is transmitted according to the present invention described above with reference to the drawings will be described.

1 is a block diagram of a signaling mapping apparatus for transmitting only a response signal according to the present invention. Next, a block configuration and operation of the signaling mapping apparatus for transmitting only the response signal according to the present invention will be described with reference to FIG. 1.

The apparatus of FIG. 1 according to the present invention is composed of a transmission count counter (not shown in FIG. 1), a controller 111, a signal point mapper 112, and a channel gain 113. The transmission count counter generates and outputs a transmission count signal nth tx indicating which physical layer packet is transmitted from the mobile station. The transmission count signal output from the transmission count counter is input to the controller 111. The controller 111 performs a control operation of adjusting the signaling mapping of the ACK / NAK and the gain for the channel according to the present invention. That is, in the case of the initial transmission as the first transmission, the controller 111 unipolar maps the signal of the ACK / NAK to +1/0. In the first transmission, the channel gain value is twice as large as the second transmission. This is due to the unipolar's use of more power. However, since the probability that the received signal is NAK is much greater, a '0' that maps to the NAK signal occurs more often. As a result, the power consumed when applying the present invention is lowered.

In the second packet transmission, bipolar signal mapping with high power efficiency is used because there is no big difference in the frequency of occurrence of ACK / NAK. The last third packet is controlled not to transmit ACK / NAK. That is, the signal point mapper 112 is gated off. This configures the response signal not to be transmitted.

The signal point mapper 112 maps and outputs the result value detected through the CRC test of the received signal under the control of the controller 111. That is, when the received signal is good (ACK) according to the CRC test result, the value of 0 is mapped and output according to the control signal output from the controller 111, and when the received signal is bad (NAK), the value of 1 is output. According to the control signal output from the controller 111 is mapped and output. In addition, the mapped output value of the signal point mapper 112 is input to the channel gain 113. Accordingly, the channel gain 113 multiplies the gain value output from the controller 111 and transmits the mapped response signal through the wireless channel.

2 is a block diagram of a signaling mapping apparatus for simultaneously transmitting a response signal and a scheduling signal according to another embodiment of the present invention. Next, a block configuration and operation of a signaling mapping apparatus for simultaneously transmitting a response signal and a scheduling signal according to the present invention will be described with reference to FIG. 2.

The configuration of FIG. 2 also includes a transmission count counter (not shown in FIG. 2), a controller 211, a signal point mapper 212, and a channel gain 213 as in the configuration of FIG. 1. The transmission count counter generates and outputs a transmission count signal nth tx indicating which physical layer packet is transmitted from the mobile station. In addition, the transmission count signal output from the transmission count counter is input to the controller 211. According to the present invention, the controller 211 performs a control operation of signaling mapping of ACK / NAK / ACK continue and adjusting a gain against a transmitted radio channel. The control signal for signaling mapping is input to the signal point mapper 212, and the channel gain value is input to the channel gain 213.

The controller 211 receives the transmission count value, and when the transmission count value of the received physical layer packet is to transmit the ACK signal for the first and second signals, the controller 211 should transmit the NAK signal. In this case, a control signal is output to the signal point mapper 212 so as to map '0' and '-1' in the case of ACK and continue. As described above, in the case of the third packet, which is the last packet, the controller 211 maintains the mobile terminal to transmit a packet of an amount corresponding to a resource occupied by the packet currently being transmitted. ) Is controlled to be mapped to '+1', and if it is not maintained, it is mapped to '-1'.

In this configuration, since bipolar signaling transmission is used even when using scheduling, power consumption is reduced as compared with the case of using + 1/0 / -1.

The signal point mapper 212 outputs a value obtained by mapping the result value detected through the CRC test of the received signal under the control of the controller 211. The mapped output value of the signal point mapper 212 is input to a channel gainer 313. Accordingly, the channel gain 213 multiplies the gain value output from the controller 211 and transmits the mapped response signal through the wireless channel.

As described above, when the forward response signal is generated in the H-ARQ mobile communication system as in the present invention, the throughput of the forward link can be maximized, the overhead can be reduced, and the error of the response signal can be reduced. have. In addition, in the case of applying the present invention, there is an advantage that the power efficiency of the response signal transmitted in the forward direction in the mobile communication system of the H-ARQ method.

Claims (12)

An apparatus for transmitting a forward response signal in a mobile communication system for transmitting only a response signal in a complex automatic retransmission method, A signal point mapper which maps and outputs a response signal according to the mapping control signal; And a controller that maps a signal of '0' to a signal having a higher probability of transmitting a good reception (ACK) or a bad reception (NAK) when transmitting a response signal to the received physical layer packet. Apparatus for transmitting forward response signal. The method of claim 1, And the controller controls not to transmit a response signal when the last retransmission packet is received. An apparatus for transmitting a forward response signal in a mobile communication system for transmitting a response signal and scheduling information together in a complex automatic retransmission method, A signal point mapper which maps and outputs a response signal and scheduling information according to the mapping control signal; When transmitting a response signal for the received physical layer packet and the scheduling information, a signal having a higher probability of transmitting a good reception (ACK) or a bad reception (NAK) is mapped to a signal of '0' and the scheduling information. Is a controller for mapping to a signal having a sign opposite to a signal that is not mapped to a signal of '0'. The method of claim 3, And the controller controls not to transmit a response signal when the last retransmission packet is received, but to map to a signal having mutually opposite signs depending on whether it is maintained by scheduling information. An apparatus for transmitting a forward response signal in a mobile communication system for transmitting only a response signal in a complex automatic retransmission method, A counter for counting the number of times of transmission of the received physical layer packet and outputting the counted value; A signal point mapper which maps and outputs a response signal according to the mapping control signal; If the received physical layer packet is the first packet, the mapping of the response signal is controlled in a unipolar manner. If the received physical layer packet is the first packet, and if it is not the last packet, the mapping of the response signal is controlled in a bipolar manner. And a controller for outputting a mapping control signal to gate off the signal point mapper. The method of claim 5, The apparatus further includes a channel gain outputting the output of the signal point mapper by controlling the gain according to a channel gain control value. And the controller controls the gain control value of the channel gain according to the number of transmissions. An apparatus for transmitting a forward response signal in a mobile communication system for simultaneously transmitting a response signal and scheduling information in a complex automatic retransmission method, A counter for counting the number of times of transmission of the received physical layer packet and outputting the counted value; A signal point mapper which maps and outputs a response signal according to the mapping control signal; If the received physical layer packet is not the last packet, control is performed to transmit information of good reception, bad reception, good reception, and channel resource retention, and outputs a mapping control signal to indicate only whether the channel resource is maintained. And a controller for transmitting the forward response signal. The method of claim 7, wherein The apparatus further includes a channel gain outputting the output of the signal point mapper by controlling the gain according to a channel gain control value. And the controller controls the gain control value of the channel gain according to the number of transmissions. A method for transmitting a forward response signal for a physical layer packet received in a reverse direction in a mobile communication system transmitting only a response signal in a complex automatic retransmission method, Controlling the mapping of the response signal in a unipolar manner when the received physical layer packet is the first packet; Controlling the mapping of the response signal in a bipolar manner when the received physical layer packet is after the first and not the last packet; And if the received physical layer packet is the last packet, gate-off the signal point mapper. 10. The method of claim 9, And a channel gain for the response signal is set differently according to the unipolar scheme or the bipolar scheme. A method of transmitting a forward response signal for a physical layer packet received in a reverse direction in a mobile communication system transmitting a response and scheduling information together in a complex automatic retransmission scheme, If the received physical layer packet is not the last packet, transmitting information of good reception, bad reception, good reception, and channel resource maintenance; If the received physical layer packet is the last packet, transmitting information indicating only whether the channel resource is maintained. delete

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