802.11 Buffers: When Bigger is Not Better?

hamilton.ie

Abstract—We consider the sizing of network buffers in 802.11 based networks. Wireless networks face a number of fundamental issues that do not arise in wired networks. We demonstrate that the use of fixed size buffers in 802.11 networks inevitably leads to either undesirable ...

IOP Conference Series: Materials Science and Engineering

Radio technology for wireless local area network (WLAN) has been used widely as it is the most popular for internet access point both in houses and buildings. Technology development rapidly changes to improve connection speed from modulation techniques to application layer, such as buffering. Some buffering methods have been employed for application adaptation. Buffer management is able improving network performances. In order to measure how buffering influence the performance, this article examines buffer queue interface impact to 802.11 performance by using network simulator. The evaluation results show that the increment on buffer size from 10 packet to100 packet boosts packet delay and jitter about 121.96% and 17% subsequently. However, packet loss is reduced up to 59%.

Computer Networks, 2009

2012 IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM), 2012

Sizing Internet buffers has recently become a popular topic. While Internet connections have become larger in bandwidth, latency has increased-and latency is a crucial factor for the performance of the applications running over the Internet. Several proposals have been made to reduce the buffer size and thereby also latency, mainly by focusing on the core routers in the Internet's backbone. However, little has been done to investigate buffer sizing on access links (known as bufferbloat problem), and more specifically in 802.11 access points. The nature of an 802.11 channel makes buffer sizing issues different than in wired networks because of the frequent changes in the service time due to changes in the bandwidth and delay-caused e.g. by rate adaptation (RA) due to noise, interference and contention as well as the DCF mechanism. In this paper, we briefly present our latest efforts to investigate AP buffer sizing in 802.11 networks.

Communications Letters, IEEE, 2008

2006

The use of 802.11 to transport delay sensitive traffic is becoming increasingly common. This raises the question of the tradeoff between buffering delay and loss in 802.11 networks. We find that there exists a sharp transition from the low-loss, lowdelay regime to high-loss, high-delay operation. Given modest buffering at the access point, this transition determines the voice capacity of a WLAN and its location is largely insensitive to the buffer size used.

Wireless Networks, 2001

The IEEE 802.11 MAC protocol provides shared access to a wireless channel. This paper uses an analytic model to study the channel capacity -i.e., maximum throughput -when using the basic access (two-way handshaking) method in this protocol. It provides closed-form approximations for the probability of collision p, the maximum throughput S and the limit on the number of stations in a wireless cell.

2010

We identify common hypotheses on which a large number of distinct mathematical models of WLANs employing IEEE 802.11 are founded. Using data from an experimental test bed and packet-level ns-2 simulations, we investigate the veracity of these hypotheses. We demonstrate that several of these assumptions are inaccurate and/or inappropriate.

Sixth IEEE International Symposium on a World of Wireless Mobile and Multimedia Networks, 2005

We present in this paper an analytical model that accounts for the positions of stations with respect to the Access Point (AP) while evaluating the performance of 802.11 MAC layer. Our work is based on the Bianchi's model where the performance of 802.11 MAC layer is computed using a discrete time Markov chain, but where all stations are implicitly assumed to be located at the same distance to the AP. In our model, given the position of one station, we compute its saturation throughput while conditioning on the positions of the other concurrent stations. Further, our model provides the total saturation throughput of the medium. We solve the model numerically and we show that the saturation throughput per station is strongly dependent not only on the station's position but also on the positions of the other stations. Results confirm that a station achieves a higher throughput when it is closer to the AP but bring out that there is a distance threshold above which the throughput decrease is fast and significant. When a station is far from the AP compared to the other stations, it will end up by contending for the bandwidth not used by the other stations. We believe that our model is a good tool to dimension 802.11 wireless access networks and to study their capacities and their performances.

IEEE 802.11n wireless LANs provide high-speed data transfer. If the radio condition degrades, however, the transfer rate will be reduced significantly and there may be some problems in the data transfer. In order to clarify this problem, we have evaluated the TCP performance over IEEE 802.11n LAN by changing the distance between the access point and a terminal. As a result, a severe increase of round trip time has been measured in the case of low data rate. This is a sort of bufferbloat problem, which is being actively studied in recent years. The detailed analysis of this experiment is our first contribution. We have inferred that one of the reasons for this increased delay is the powerful retransmission function of 802.11n. So, we propose, as the second contribution, a method to improve TCP delay performance by reducing this retransmission capability and by generating TCP segment loss intentionally. This paper describes the performance evaluations for our proposal in comparison wi...