A Survey of Rate-Adaptation Schemes for IEEE 802.11 Compliant WLANs

( Shahbaz Khan ),( Sadiq Ullah ),( Aziz Ahmed ),( Sahibzada. A. Mahmud ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.3

The IEEE 802.11 compliant stations can transmit at multiple transmission rates. Selection of an appropriate transmission rate plays a significant role in determining the overall efficiency of a communication system. The technique which determines the channel state information and accordingly selects an appropriate transmission rate is called rate-adaptation protocol. The IEEE 802.11 standard does not provide standard specification for implementing a rate-adaptation protocol for its multi-rate capable wireless stations. Due to the lack of standard specification, there is a myriad of rate-adaptation protocols, proposed by industry and various research institutes. This paper surveys the existing rate-adaptation schemes, discusses various features which contribute significantly in the process of rate-adaptation, the timing constraints on such schemes, and the performance gains in terms of throughput, delay and energy efficiency; which can be gained by the use of rate-adaptation. The paper also discusses the implication of rate-adaptation schemes on the performance of overall communication and identifies existing research challenges in the design of rate-adaptation schemes.

CARA: IEEE 802.11 무선랜에서 충돌을 인지한 적응적 전송속도 조절기법

김종석,김성관,최성현,Kim, Jong-Seok,Kim, Seong-Kwan,Choi, Sung-Hyun 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.2A

IEEE 802.11 무선랜(Wireless LAN)은 다수의 전송속도(transmission rate)를 지원하고 있으며, 채널 상태에 따라 전송속도를 적응적으로 조절함으로써 시스템 성능을 최대화할 수 있다. 지금까지 많은 종류의 전송속도 조절기법들이 제안되어 왔으나 최근까지 대부분의 상용제품에 구현된 기법은 ARF(Automatic Rate Fallback)라는 간단한 open-loop 전송속도 조절기법이다. 이러한 open-loop 전송속도 조절기법의 가장 큰 문제점은 데이터의 충돌현상(collision effect)을 고려하지 않는다는 것이며, 이로 인해 충돌에 의한 다수의 전송실패가 발생할 경우 시스템 성능이 급격히 낮아진다는 문제점이 있다. 이 논문에서는 CARA(Collision-Aware Rate Adaptation)라는 새로운 전송속도 조절기법을 제안하고 있다. CARA는 송신 단말이 채널에러에 의해 발생한 데이터 전송실패를 충돌에 의해 발생한 것과 구분할 수 있도록 적응적으로 CCA(Clear Channel Assessment)와 RTS/CTS(Request-to-Send/Clear-to-Send) 전송을 사용하는 기법이다. 따라서 기존의 open-loop 전송속도 조절기법과 비교할 때, CARA는 보다 정확하게 현재 채널상태에 적합한 전송속도를 선택할 수 있게 된다. 시뮬레이션을 통한 많은 실험결과들로부터 CARA는 채널상태에 관계없이 다른 기법들보다 월등히 높은 성능을 나타낸다는 것을 알 수 있다. Today's IEEE 802.11 WLANs(Wireless LANs) provide multiple transmission rates so that different rates can be exploited in an adaptive manner depending on the underlying channel condition in order to maximize the system performance. Many rate adaptation schemes have been proposed so far while most(if not all) of the commercial devices implement a simple open-loop rate adaptation scheme(i.e., without feedback from the receiver), called ARF(Automatic Rate Fallback) due to its simplicity. A key problem with such open-loop rate adaptation schemes is that they do not consider the collision effect, and hence, malfunction severely when many transmission failures are due to collisions. In this paper, we propose a novel rate-adaptation scheme, called CARA(Collision-Aware Rate Adaptation). The key idea of CARA is that the transmitter station combines adaptively the Request-to-Send/Clear-to-Send(RTS/CTS) exchange with the Clear Channel Assessment(CCA) functionality to differentiate frame collisions from frame transmission failures cause by channel errors. Therefore, compared with other open-loop rate adaptation schemes, CATA is more likely to make the correct rate adaptation decisions. Through extensive simulation runs, we evaluate our proposed scheme to show that our scheme yields significantly higher throughput performance than the existing schemes in both static and time-varying fading channel environments.

Adaptive data rate control in low power wide area networks for long range IoT services

Kim, Dae-Young,Kim, Seokhoon,Hassan, Houcine,Park, Jong Hyuk Elsevier 2017 Journal of computational science Vol.22 No.-

<P><B>Abstract</B></P> <P>Internet of Things (IoT) technologies can provide various intelligent services by collecting information from objects. To collect information, Wireless Sensor Networks (WSNs) are exploited. The Low Power Wide Area Network (LPWAN), one type of WSN, has been designed for long-range IoT services. It consumes low power and uses a low data rate for data transmission. The LPWAN includes several communication standards, and Long Range Wide Area Network (LoRaWAN) is the representative standard of the LPWAN. LoRaWAN provides several data rates for transmission and enables adaptive data rate control in order to maintain network connectivity. In the LoRaWAN, the wireless condition is considered by the reception status of the acknowledgement (ACK) message, and adaptive data rate control is performed according to the wireless condition. Because the judgment of the wireless condition by the reception status of ACK messages does not reflect congestion, adaptive data rate control can lead to inefficiency in data transmission. For efficient data transmission in long-range IoT services, this paper proposes a congestion classifier using logistic regression and modified adaptive data rate control. The proposed scheme controls the data rate according to the congestion estimation. Through extensive analysis, we show the proposed scheme’s efficiency in data transmission.</P> <P><B>Highlights</B></P> <P> <UL> <LI> In this paper, the necessity of congestion estimation in long range IoT applications is described. Congestion Classifier using Logistic Regression and the modified adaptive data rate control scheme is designed. </LI> <LI> For the validation of the efficiency of the data transmission, analysis on the transmission delay is carried out. Results show that the proposed method outperforms state of the art methods. </LI> <LI> In this way, the proposal improves transmission efficiency in aspect of the transmission delay in wireless environment where congestion occurs. </LI> <LI> Our proposed method predicts congestion status by learning and determines whether a node drops data rate or not. Thus, it leads to avoiding unnecessary change of data rate. </LI> <LI> Through analysis on transmission delay, the proposed scheme has shown that it is the proper data rate control method for IoT networking in congestion environment. </LI> </UL> </P>

An Optimal Framework of Video Adaptation and Its Application to Rate Adaptation Transcoding

Jae-Gon Kim,김형명,Yong Wang,Shih-Fu Chang 한국전자통신연구원 2005 ETRI Journal Vol.27 No.4

The adaptation of video according to the heterogeneous and dynamic resource constraints on networks and devices, as well as on user preferences, is a promising approach for universal access and consumption of video content. For optimal adaptation that satisfies the constraints while maximizing the utility that results from the adapted video, it is necessary to devise a systematic way of selecting an appropriate adaptation operation among multiple feasible choices. This paper presents a general conceptual framework that allows the formulation of various adaptations as constrained optimization problems by modeling the relations among feasible adaptation operations, constraints, and utilities. In particular, we present the feasibility of the framework by applying it to a use case of rate adaptation of MPEG-4 video with an explicit modeling of adaptation employing a combination of frame dropping and discrete cosine transform coefficient dropping, constraint, utility, and their mapping relations. Furthermore, we provide a description tool that describes the adaptation-constraint-utility relations as a functional form referred to as a utility function, which has been accepted as a part of the terminal and network quality of service tool in MPEG-21 Digital Item Adaptation (DIA).

다중 전송율 무선랜에서의 스케일러블 비디오 멀티캐스트를 위한 품질 기반 전송 속도 적응 기법

박광우 ( Gwangwoo Park ),장인선 ( Insun Jang ),백상헌 ( Sangheon Pack ) 한국정보처리학회 2012 정보처리학회논문지. 컴퓨터 및 통신시스템 Vol.1 No.1

무선 멀티캐스트 서비스는 동일한 콘텐츠를 다수의 사람들에게 동시에 전송함으로써 네트워크 자원을 보다 효율적으로 이용할 수 있다. 본 논문에서는 더 나은 무선 멀티미디어 스트리밍 멀티캐스트 서비스를 제공하기 위하여 Quality-Aware Rate Adaptation(QARA) 기법을 제시한다. QARA에서는 콘텐츠의 종류와 사용자의 채널 환경에 따라 멀티캐스트 프레임의 전송 속도가 결정된다. 기본 계층은 높은 신뢰성을 보장하기 위하여 낮은 속도를 이용하여 모든 사용자들에게 전송됨으로써 기본적인 서비스 품질을 제공한다. 반면, 향상 계층의 프레임 전송 속도는 무작위로 선출된 노드의 채널 환경 피드백 정보를 통하여 결정된다. 콘텐츠 전송 중에 이러한 과정을 반복함으로써 다양한 전송 속도를 사용하고, 각 노드들에게 채널 환경에 따라 차등적인 서비스를 제공할 수 있다. 결과적으로 QARA는 이동 노드들이 다양하게 분포되어 있는 환경에 사용될 수 있으며, 네트워크 자원을 보다 효율적으로 이용할 수 있다. 시뮬레이션 결과는 QARA가 기존 연구들에 비하여 높은 가능 전송 속도활용률을 보임으로써 콘텐츠 전송 시간을 단축시킬 수 있음을 보여준다. Wireless multicast service can be used for video streaming service to save the network resources by sending the same popular multimedia contents to a group of users at once. For better multimedia streaming multicast service, we propose a quality-aware rate adaptation (QARA) scheme for scalable video multicast in rate adaptive wireless networks. In QARA, transmission rate is determined depending on the content``s type and users`` channel conditions. First, the base layer is transmitted by a low rate for high reliability. That means we provide basic service quality to all users. On the contrary, the transmission rate for enhancement layer is adapted by using channel condition feedback from a randomly selected node. So, the enhancement layer frames in a multimedia content is sent with various transmission rates. Therefore, each node can be provided with differentiated quality services. Consequently, QARA is capable of serving heterogeneous population of mobile nodes. Moreover, it can utilize network resources more efficiently. Our simulation results show that QARA outperforms utilization of the available transmission rate and reduces the data transmission time.

이동 망에서의 전송률 적응 방안

조현준(Hyun Joon Cho) 한국정보처리학회 2000 정보처리학회논문지 Vol.7 No.12

In mobile network, wireless links may be overloaded due to a high concentration of mobile hosts in a given cell. As a result, the required QOS(Quality of Service) cannot be provided to all flows in that cell. So, there exists adaptive applications which can operate with various bandwidth levels. When a wireless link is overloaded, it can adapt by reducing the bandwidths of flows, is referred to as rate adaptation. In this paper, we analyze the performance of existing rate adaptation methods by simulations. The result of simulation experiments shows that average-fair adaptation scheme has very low network overhead but high bandwidth variance of flows, which causes the worse quality of service. We propose a rate adaptation method refined by combining fair adaptation and average-fair adaptation, and shows the refined method can provide lower bandwidth variance of flows by simulations.

저출산 극복의 새로운 길, 저출산 적응정책

서동희(Seo, Dong Hee) 한국공공사회학회 2015 공공사회연구 Vol.5 No.1

저출산의 위기는 세 가지로 볼 수 있다. 첫 번째는 흔히 일반적으로 일컫는 저출산으로 인한 노동력 감소, 인구 구조의 불균형이고, 두 번째는 막대한 정부의 예산 투입에도 불구하고 미미한 출산율 상승이다. 세 번째는 저출산의 추세에 적응하지 못한 체 막연한 저출산에 대한 부정적인 시각에 있다. 10년 가까운 저출산 극복정책에도 그 효과가 거의 나타나지 않는다는 현실은 정책의 획기적인 변화를 가져와야 할 때라는 경고이다. 상당히 복잡하게 얽혀있는 한국의 저출산 원인을 사회구조적인 측면에서 전폭적으로 개혁하지 못한다면 이제 정책의 방향을 바꾸어 저출산 적응을 위한 대안 마련을 모색해야 한다. 출산율 상승을 위한 노력과 더불어 저출산 시대에 야기 될 수 있는 노동력 부족 문제, 1인 가구주들의 안녕과 관련되는 복지. 심리 등의 문제들을 위한 정책의 전환점이 필요하다. 따라서 여성과 노인의 노동력 확보, 외국으로부터 노동력의 유입, 다문화 가족을 통한 경쟁력 확보, 1가구주를 위한 조합적 주거정책 등을 대안으로 제시한다. The crisis of low birth rate can be summarized under three headings ; The first is the reduction of labor power and unbalance of population structure that are generally mentioned. The second is very little increase of birth rate in spite of huge expenditure of government budget. The third is vaguely negative view on the low birth rate without adapting the trend of low birth rate. For the last 10 years, the policy to overcome low birth rate has not been effective. This is a kind of warning that great change is needed. If it is not possible for us to address the complex cause of low birth rate in terms of socio-structure, we need to change direction of policy and search for the options that adapts low birth rate. The change of policies is needed to tackle the following agenda : efforts to increase birth rate, lack of labor power casused by low birth rate, one person families" welfare and psychology that are related to their safety. Therefore, this paper proposes some options such as securing female and elderly labor power, flowing in labor power from foreign countries, securing competitiveness through multi-culture families, Cooperative housing policy for one person families

Multi-Rate and Multi-BEP Transmission Scheme Using Adaptive Overlapping Pulse-Position Modulator and Power Controller in Optical CDMA Systems

Miyazawa Takaya,Sasase Iwao The Korea Institute of Information and Commucation 2005 Journal of communications and networks Vol.7 No.4

We propose a multi-rate and multi-BEP transmission scheme using adaptive overlapping pulse-position modulator (OPPM) and optical power controller in optical code division multiple access (CDMA) networks. The proposed system achieves the multi-rate and multi-BEP transmission by accommodating users with different values of OPPM parameter and transmitted power in the same network. The proposed scheme has advantages that the system is not required to change the code length and number of weight depending on the required bit rate of a user and the difference of bit rates does not have so much effect on the bit error probabilities (BEPs). Moreover, the difference of transmitted powers does not cause the change of bit rate. We analyze the BEPs of the four multimedia service classes corresponding to the com­binations of high/low-rates and low/high-BEPs and show that the proposed scheme can easily achieve distinct differentiation of the service classes with the simple system configuration.

효율적인 비디오 스트리밍을 위한 일시적인 확장성을 이용한 품질 적응 기법

이선헌(Sunhun Lee),정광수(Kwangsue Chung) 한국정보과학회 2007 정보과학회논문지 : 정보통신 Vol.34 No.3

인터넷을 통한 비디오 스트리밍 응용에서 TCP 친화적인 전송률 조절기법은 네트워크의 안정성을 향상시키고 프로토콜간의 형평성을 향상시킨다는 장점을 가진다. 하지만, 네트워크의 안정성 및 프로토콜간의 형평성 향상이 사용자에게 제공되는 스트리밍 서비스 품질의 향상을 의미하진 않는다. 비디오 스트리밍에서 네트워크의 안정성 향상과 동시에 사용자에게 제공되는 서비스 품질의 향상을 위해서는 네트워크 상태를 기반으로, 서비스되는 비디오 스트림의 품질을 적응적으로 변화시키는 기법이 적용되어야 한다. 본 논문에서는 현재 네트워크의 상태를 기반으로 서비스되는 비디오 스트림의 품질을 조절하는 새로운 품질 적응 기법을 제안하고자 한다. 제안하는 기법은 현재 네트워크 상태에 적합한 TCP 친화적인 전송률을 계산하고, 이를 기반으로 전송되는 비디오 스트림의 프레임율을 조절함으로써 네트워크 상태에 적응적으로 전송률 및 서비스 품질을 조절하게 된다. 실험 결과를 통해서 제안하는 기법이 네트워크의 안정성을 향상시킴과 동시에 네트워크 상태 적응적인 품질 변화를 통해 사용자에게 끊김없이 부드러운 스트리밍 서비스를 제공할 수 있음을 확인할 수 있었다. In video streaming applications over the Internet, TCP-friendly rate control schemes are useful for improving network stability and inter-protocol fairness. However it does not always guarantee a smooth quality for video streaming. To simultaneously satisfy both the network and application requirements, video streaming applications should be quality-adaptive. In this paper, we propose a new quality adaptation mechanism to adjust the quality of congestion controlled video stream by controlling the frame rate. Based on the current network condition, it controls the frame rate and sending rate of video stream. Through the simulation, we prove that our adaptation mechanism appropriately adjusts the quality of video stream while improving network stability.

Efficient Rate-Adaptive Reconciliation Based on LDPC Accumulate Codes for Quantum Key Distribution

Tharathorn Phromsa-ard,Patcharapong Treeviriyanupab,Paramin Sangwongngam,Keattisak Sripimanwat,Kamol Kaemarungsi,Pisit Vanichchanunt,Lunchakorn Wuttisittikulkij 대한전자공학회 2015 ITC-CSCC :International Technical Conference on Ci Vol.2015 No.6

In this paper, a rate-adaptive method is proposed an alternative reconciliation protocol by employing the LDPC-accumulate codes to the practical implementation in the quantum key distribution (QKD). The proposed rate-adaptive reconciliation is adapted in the Slepian-Wolf scheme where specific low-density parity-check (LDPC) codes are constructed by accumulated syndrome encoding/decoding. Its objective is to skip the step of quantum bit error rate (QBER) estimation by the traditional key sampling that increases the final secret key length in practice. From the numerical results, the proposed method achieves a good performance in terms of the number of disclosed bits and reconciliation efficiency comparable to the conventional Winnow, Cascade, and fixed-rate compatible LDPC based protocols. Moreover, it can cover the possible cases of error rates in the QKD system. Therefore, method is suitable for the highspeed discrete-variable QKD applications.