KR20000037706A - Retransmitting method of mobile communication system - Google Patents

Retransmitting method of mobile communication system Download PDF

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KR20000037706A
KR20000037706A KR1019980052355A KR19980052355A KR20000037706A KR 20000037706 A KR20000037706 A KR 20000037706A KR 1019980052355 A KR1019980052355 A KR 1019980052355A KR 19980052355 A KR19980052355 A KR 19980052355A KR 20000037706 A KR20000037706 A KR 20000037706A
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packet
length
error rate
packet error
mobile communication
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KR1019980052355A
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KR100281653B1 (en
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엄화영
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정선종
한국전자통신연구원
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/30—Monitoring; Testing of propagation channels
    • H04B17/309—Measuring or estimating channel quality parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
    • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
    • H04B7/2612—Arrangements for wireless medium access control, e.g. by allocating physical layer transmission capacity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0006—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission format
    • H04L1/0007—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission format by modifying the frame length

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Quality & Reliability (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

PURPOSE: A retransmitting method of the mobile communication system is provided to improve the information processing ratio of typical retransmitting methods, such as stop-and wait, go-back-N, selective-repeat, etc., by adjusting the length of a protocol packet dynamically according to the environment of wireless channels. CONSTITUTION: To improve an information processing ratio by adjusting the length of a protocol packet dynamically after detecting and measuring the variation of wireless channels in the mobile communication system, a packet error ratio table is configured(S1). The calculation of a packet error ratio is carried out at the rate of an error packet out of received packets to set up a threshold value(S2). It is judged whether a packet error ratio under actual transmission exceeds the threshold value(S3). In case that the packet error ratio exceeds the threshold value, the length of the packet is adaptively varied(S4).

Description

이동통신 시스템의 재전송 방법Retransmission method of mobile communication system

본 발명은 이동통신 시스템의 재전송 방법에 관한 것으로서, stop-and-wait(SW), go-back-N, selective-repeat(SR)과 같은 전형적인 재전송 방법의 정보처리율은 무선채널의 환경에 따라서 동적으로 프로토콜 패킷의 길이를 조정하여 향상시킬 수 있는데, 이때 어떻게 무선채널의 변화를 측정하고 감지하여 반영시킬 수 있는가에 하는데 문제가 있다.The present invention relates to a retransmission method of a mobile communication system, wherein the information throughput of typical retransmission methods such as stop-and-wait (SW), go-back-N, and selective-repeat (SR) is dynamic depending on the environment of the wireless channel. By adjusting the length of the protocol packet can be improved, there is a problem in how to measure, detect and reflect the change in the radio channel.

또한 무선채널의 상태를 감지하기 위해서는 이동국(Mobile Terminal)의 속도, 신호대 잡음비의 비율, 패킷의 에러율(Packet Error Ratio) 및 패킷내의 에러내의 에러 비트율(Bit Error Ratio in Packet) 등을 알아야 하는데 이것은 신호처리 측면에서 계산량이 늘어나게 된다.In addition, in order to detect the state of the wireless channel, the speed of the mobile terminal, the ratio of signal to noise ratio, the packet error ratio and the bit error ratio in the packet must be known. In terms of processing, the amount of calculation increases.

일반적으로 채널의 상태는 측정주기 동안의 재전송 비율을 누적하여 기준치와 비교하는 방법으로 감시하는데, 이때 측정주기가 매우 길면 측정치에는 신뢰성이 있지만 채널의 상태 변화에 반영하기에는 지연이 야기되며, 반대로 측정주기가 짧을 경우 측정값에 신뢰성이 결여되는 문제점이 있다.In general, the state of the channel is monitored by accumulating the rate of retransmission during the measurement period and comparing it with the reference value.In this case, if the measurement period is very long, the measurement value is reliable but a delay occurs to reflect the change in the state of the channel. If is short, there is a problem that the measurement value lacks reliability.

상기 문제점을 해결하기 위해 본 발명은, 이동통신 환경에서 무선채널의 상태에 따라 적응적으로 패킷의 길이를 조정하여 정보처리율을 높이기 위해 요구되는 무선채널의 상태 변화를 쉽게 측정하는 방법을 제공하는데 있어서, 기존의 방법과 비교하여 쉽고 빠르게 채널의 변화를 추정할 수 있는 방법을 제공하는 것을 목적으로 한다.In order to solve the above problems, the present invention provides a method for easily measuring the change in the state of the radio channel required to increase the information throughput by adaptively adjusting the length of the packet according to the state of the radio channel in the mobile communication environment. In addition, it is an object of the present invention to provide a method for estimating a change in a channel easily and quickly in comparison with a conventional method.

적응적 패킷 길이 변화 방법을 적용하는데 있어서 가장 어려운 문제점은, 어떻게 단순하지만 실시간적으로 처리가 가능하도록 무선채널의 상태를 감시하느냐에 달려있는데, 본 발명은 수신된 전력의 세기나 이동국의 속도를 이용하기보다는 재전송 요구 횟수를 이용하여 무선 환경의 변화를 측정하는 것이 구현하기 쉽다.The most difficult problem in applying the adaptive packet length variation method depends on how to monitor the state of the radio channel so that it can be processed in a simple but real-time manner. The present invention uses the strength of the received power or the speed of the mobile station. Rather, it is easier to measure changes in the wireless environment using the number of retransmission requests.

이 방법을 이용하는 경우에는 예측한 패킷의 에러율과 실제 패킷의 에러율의 차이를 줄이는 방법이 매우 중요하다.When using this method, it is very important to reduce the difference between the predicted packet error rate and the actual packet error rate.

상기 목적을 달성하기 위해 본 발명은, 이동통신 시스템에서 무선채널의 변화를 측정하고 감지하여 동적으로 프로토콜 패킷의 길이를 조정하여 정보처리율을 향상시키고자 무선채널의 상태 변화를 측정하기 위해, 패킷 에러 테이블을 구성한 후, 구성된 패킷 에러 테이블을 무선 환경의 변화에 따라서 테이블을 재구성하고 각각의 상태에서 주기를 변화시켜 적응적 패킷 길이를 갖도록 변화시킴으로써, 쉽고 빠르게 채널의 상태를 추정할 수 있고, 무선채널의 상태에 따라 다양한 측정주기와 적절한 패킷 길이를 가질 수 있으므로 매우 성능을 향상시킬 수 있는 일반화된 방법을 제시할 수 있는 특징이 있다.In order to achieve the above object, the present invention, in order to measure the change in the radio channel in the mobile communication system to dynamically adjust the length of the protocol packet to improve the information processing rate to measure the state of the radio channel, packet error After constructing the table, it is possible to easily and quickly estimate the state of the channel by reconstructing the configured packet error table according to changes in the wireless environment and changing the period in each state to have an adaptive packet length. It can have various measurement cycles and proper packet lengths according to the state of, which can provide a generalized way to improve performance.

도 1은 본 발명에 따른 두개의 상태를 가지는 적응적인 재전송 방법에 대한 마코프 체인 모델 구조도,1 is a structural diagram of a Markov chain model for an adaptive retransmission method having two states according to the present invention;

도 2는 본 발명이 적용되는 적응적 패킷 길이를 갖는 재전송 방법 흐름도.2 is a flowchart of a retransmission method having an adaptive packet length to which the present invention is applied.

* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings

10 : 낮은 채널 에러율의 a 상태10: a state of low channel error rate

20 : 높은 채널 에러율의 b 상태20: b state of high channel error rate

이하 첨부된 도면을 참조하여 본 발명을 상세히 설명하면 다음과 같다.Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

채널의 상태를 감시하는 방법은 연속적으로 성공(AcKs)과 실패(NACKs) 한 패킷의 개수를 세는 것이다.The way to monitor the state of the channel is to count the number of packets that have successively succeeded (AcKs) and failed (NACKs).

이때 측정주기는 채널의 상태에 따라 다른데, 어떤 상태에서 다른 상태로의 천이는 연속적으로 수신된 성공 개수와 실패 개수에 좌우되며, 이러한 모델을 도 1에 나타내었다.In this case, the measurement period varies depending on the state of the channel. The transition from one state to another depends on the number of successes and failures received in succession, and this model is illustrated in FIG. 1.

상기 도 1에서 2개의 패킷 길이에 대한 상태천이를 보여주고 있는데, 이때 상태의 개수(a, b)는 무선 환경에 따라 적절하게 선택할 수 있다.In FIG. 1, state transitions for two packet lengths are shown. In this case, the number of states a and b may be appropriately selected according to a wireless environment.

여기에서 제안된 마코프 체인 모델은 r차 마코프 프로세스를 일반화한 것이다.The Markov chain model proposed here is a generalization of the rth order Markov process.

먼저, 최적의 패킷 길이를 구하는 방법은 아래 수학식 1과 같다.First, a method of obtaining an optimal packet length is as shown in Equation 1 below.

여기서 h는 패킷의 오버헤드비트 개수(the number of overhead bits packet), Ω은 , fD 는 도플러 주파수(Doppler frequency), R은 데이터 율(Data Rate) 및 ρ은 한계전력 레벨과 수신전력 레벨 사이의 비율(ratio between the threshold power level and mean received power level)을 각각 나타낸다.Where h is the number of overhead bits packet and Ω is , f D Is the Doppler frequency, R is the data rate, and ρ is the ratio between the threshold power level and the received power level, respectively.

그리고 적응적으로 패킷의 길이를 변화시키는 경우의 정보처리율은, 다음의 수학식 2와 같다.The information processing rate in the case of adaptively changing the length of the packet is expressed by the following expression (2).

다음으로 패킷 에러율 테이블을 결정하는 방법으로는, 패킷 에러율에 따라 테이블을 구성하여 해당 임계치에 의해서 패킷의 길이를 결정한다.Next, as a method of determining the packet error rate table, a table is constructed according to the packet error rate, and the length of the packet is determined based on the threshold.

먼저, 상기 한계전력 레벨과 수신전력 레벨 사이의 비율(ρ)이 고정되는 경우는, 다음 수학식 3과 4를 이용하여 계산했을 때, 블록의 에러율이 상기 수학식 3보다 크고 수학식 4보다 작은 경우에는 패킷의 길이가 ni에서 ni+1로 천이된다.First, when the ratio ρ between the threshold power level and the reception power level is fixed, the error rate of the block is greater than Equation 3 and less than Equation 4 when calculated using Equations 3 and 4 below. case, the length of the packet is shifted to the n i + 1 in the i n.

Pco U(i,i+1)=1-exp[ρ-niΩco]P co U (i, i + 1) = 1-exp [ρ-n i Ω co ]

Pco L(i,i+1)=1-exp[ρ-ni+1Ωco]P co L (i, i + 1) = 1-exp [ρ-n i + 1 Ω co ]

또한, 도플러 주파수( fD )가 고정되는 경우는, 아래 수학식 5와 수학식 6을 이용하여 테이블을 구성한다.In addition, the Doppler frequency ( f D ) Is fixed, a table is constructed using the following equations (5) and (6).

도 2 는 본 발명이 적용되는 적응적 패킷 길이를 갖는 재전송 방법 흐름도로서, 상기와 같은 방법으로 패킷 에러율 테이블을 구성하여(S1) 패킷 에러율 계산을 수신된 패킷중 에러패킷의 비율로 계산한 후 이 값을 임계치로 설정한다.2 is a flowchart of an adaptive transmission method having an adaptive packet length to which the present invention is applied. A packet error rate table is constructed in the same manner as described above (S1), and the packet error rate calculation is calculated as the ratio of error packets among the received packets. Set the value to the threshold.

그리고 실제 전송중의 패킷의 에러율이 임계값을 넘는지 판단하여(S3) 넘는 경우에는 패킷의 길이를 적응적으로 변화시키고(S4), 임계값을 넘지 않는 경우는 다시 패킷 에러율 계산부터 시작한다.If the error rate of the packet actually being transmitted exceeds the threshold (S3), the length of the packet is adaptively changed (S4). If the packet does not exceed the threshold, the packet error rate is calculated again.

또한 무선 환경에 따라 패킷 에러율 테이블을 재구성하여 환경 변화를 반영한다.In addition, the packet error rate table is reconfigured according to the wireless environment to reflect the environmental change.

상술한 바와 같이 본 발명은, 무선채널의 변화를 측정하고 감지하여 동적으로 프로토콜 패킷의 길이를 조정함으로써, 정보처리율을 향상시킬 수 있다.As described above, the present invention can improve information throughput by measuring and detecting a change in a wireless channel and dynamically adjusting the length of a protocol packet.

따라서 실제 이동통신 시스템에서 요구되는 무선채널의 상태 변화를 쉽게 측정하기 위해, 본 발명은 구현하기가 용이하게 성공(AcKs)과 실패(NACKs) 한 패킷의 개수를 세는 방법을 사용하여 쉽고 빠르게 채널의 상태를 추정할 수 있다.Therefore, in order to easily measure the state change of the wireless channel required in the actual mobile communication system, the present invention can be easily and quickly implemented by using a method of counting the number of successful (AcKs) and failed (NACKs) packets. The state can be estimated.

상기에 따라 본 발명은, 무선채널의 상태에 따라 다양한 측정주기와 적절한 패킷 길이를 가질 수 있으므로 기존의 방법에 비해서 매우 성능을 향상시킬 수 있는 효과가 있다.According to the above, the present invention can have various measurement periods and appropriate packet lengths according to the state of the radio channel, and thus, the performance can be greatly improved compared to the conventional method.

Claims (3)

이동통신 시스템에서 무선채널의 변화를 측정하고 감지하여 동적으로 프로토콜 패킷의 길이를 조정하여 정보처리율을 향상시키고자 무선채널의 상태 변화를 측정하는 방법에 있어서,In the method for measuring the change in the state of the wireless channel to improve the information throughput by measuring and detecting the change of the radio channel in the mobile communication system to dynamically adjust the length of the protocol packet, 패킷 에러 테이블을 구성하는 제 1 단계와;A first step of constructing a packet error table; 구성된 패킷 에러 테이블을 무선 환경의 변화에 따라서 테이블을 재구성하고 각각의 상태에서 주기를 변화시켜 적응적 패킷 길이를 갖도록 변화시키는 제 2 단계를 포함하는 것을 특징으로 하는 이동통신 시스템의 재전송 방법.And reconstructing the configured packet error table according to the change of the wireless environment and changing the period in each state to have an adaptive packet length. 제 1 항에 있어서,The method of claim 1, 상기 제 1 단계는,The first step is, 패킷 에러율에 따라 테이블을 구성하여 해당 임계치에 의해 패킷의 길이를 결정하는 것을 특징으로 하는 이동통신 시스템의 재전송 방법.And reconfiguring a table according to a packet error rate to determine the length of a packet based on a corresponding threshold. 제 1 항에 있어서,The method of claim 1, 상기 제 2 단계는,The second step, 상기와 같이 패킷 에러율 테이블을 구성하고 패킷 에러율 계산을 수신된 패킷중 에러패킷의 비율로 계산한 후 이 값을 임계치로 설정하는 제 1 부단계와;A first substep of constructing a packet error rate table as described above, calculating a packet error rate as a ratio of error packets among the received packets, and setting this value to a threshold; 실제 전송중의 패킷의 에러율이 상기 임계값을 넘는지 판단하여 넘는 경우에는 패킷의 길이를 적응적으로 변화시키는 제 2 부단계와;A second sub-step of adaptively changing the length of the packet if the error rate of the packet actually being transmitted exceeds the threshold; 상기 판단 후 임계값을 넘지 않는 경우는 다시 패킷 에러율을 계산하는 제 3 부단계와;A third substep of calculating a packet error rate if the threshold value is not exceeded after the determination; 무선 환경에 따라 상기 패킷 에러율 테이블을 재구성하여 환경 변화를 반영하는 제 4 부단계로 이루어진 것을 특징으로 하는 이동통신 시스템의 재전송 방법.And a fourth substep of reconfiguring the packet error rate table according to a wireless environment to reflect an environment change.
KR1019980052355A 1998-12-01 1998-12-01 Retransmission method of mobile communication system KR100281653B1 (en)

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KR20040020638A (en) * 2002-08-31 2004-03-09 삼성전자주식회사 Dynamic management method of packet segmentation threshold according to the wireless channel status.
KR100498928B1 (en) * 2001-07-07 2005-07-04 삼성전자주식회사 Transmitting and receiving method of data in mobile communication system
KR100516686B1 (en) * 2000-07-08 2005-09-22 삼성전자주식회사 Hybrid automatic repeat request method for cdma mobile system
KR100550464B1 (en) * 2001-08-21 2006-02-13 가부시키가이샤 엔티티 도코모 Mobile communication system, communication terminal apparatus, burst signal transmission method
KR100666127B1 (en) * 2005-04-23 2007-01-09 전자부품연구원 Transmission method of data frames using dynamic ack policy in wpan communication
KR100973003B1 (en) * 2008-09-26 2010-07-30 삼성전기주식회사 Wireless communication method using channel-adaptive acknowledgement policy
KR101267160B1 (en) * 2006-11-30 2013-05-24 삼성전자주식회사 Apparatus and method for transmitting data in a communication system

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100516686B1 (en) * 2000-07-08 2005-09-22 삼성전자주식회사 Hybrid automatic repeat request method for cdma mobile system
KR100498928B1 (en) * 2001-07-07 2005-07-04 삼성전자주식회사 Transmitting and receiving method of data in mobile communication system
KR100550464B1 (en) * 2001-08-21 2006-02-13 가부시키가이샤 엔티티 도코모 Mobile communication system, communication terminal apparatus, burst signal transmission method
US7190967B2 (en) 2001-08-21 2007-03-13 Ntt Docomo, Inc. Radio communication system, communication terminal, and method for transmitting burst signals
KR20040020638A (en) * 2002-08-31 2004-03-09 삼성전자주식회사 Dynamic management method of packet segmentation threshold according to the wireless channel status.
KR100666127B1 (en) * 2005-04-23 2007-01-09 전자부품연구원 Transmission method of data frames using dynamic ack policy in wpan communication
KR101267160B1 (en) * 2006-11-30 2013-05-24 삼성전자주식회사 Apparatus and method for transmitting data in a communication system
KR100973003B1 (en) * 2008-09-26 2010-07-30 삼성전기주식회사 Wireless communication method using channel-adaptive acknowledgement policy

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