Abstract-Our goal is to characterize the traffic load in an IEEE802.11 infrastructure. This can be beneficial in many domains, including coverage planning, resource reservation, network monitoring for anomaly detection, and producing more accurate simulation models. The key issue that drives this study is traffic forecasting at each wireless access point (AP) in an hourly timescale. We conducted an extensive measurement study of wireless users on a major university campus using the IEEE802.11 wireless infrastructure. We observed a spatial locality in the most heavily utilized APs. We propose several traffic models that take into account the periodicity and recent traffic history for each AP and present a time-series forecasting methodology. Finally, we build and evaluate these forecasting algorithms and discuss our findings. I. INTRODUCTIONWireless networks are increasingly being deployed and expanded in airports, universities, corporations, hospitals, residential, and other public areas to provide wireless Internet access. Furthermore, there is an increase in peer-to-peer, streaming, and VoIP traffic over the wireless infrastructures[9], [8]. At the same time, empirical studies and performance analysis indicate dramatically low performance of real-time constrained applications over wireless LANs (such as [2] on the VoIP). Currently APs do not perform any type of forecasting or admission control and clients frequently experience failures and disconnections when there is high demand in the wireless infrastructure.The shared medium wireless LANs have more vulnerabilities and bandwidth and latency constrains than their wired counterparts. The bandwidth utilization at an AP can impact the performance of the wireless clients in terms of throughput, delay, and energy consumption. For quality of service provision, capacity planning, load balancing, and network monitoring, it is critical to understand the traffic characteristics. While there is a rich literature characterizing traffic in wired networks ([11], [10], [15], [7]), there are only a few studies available that examined wireless traffic load. The key issue that drives this study is forecasting in an hourly time scale. We aim to enable APs to perform short-term forecasting in order to perform better load balancing, admission control, and quality of service provisioning. Specifically, they can use the expected traffic estimations to decide whether or not to accept a new association request or advise a client to associate with a neighboring AP. In addition, the traffic models can assist in detecting abnormal traffic patterns (e.g., due to malicious attacks, AP or client misconfigurations and failures).

This work explores the throughput and delay that can be achieved by various forwarding schemes, employing multiple paths and different degrees of redundancy, focusing on linear network coding. The key contribution of the study is an analytical framework for modeling the throughput and delay forvarious schemes, considering wireless mesh networks where unicast traffic is forwarded and hop-by-hop retransmissions are employed for achieving reliability. The analytical framework is generalized for an arbitrary number of paths and hops per path. Another key contribution of the study is the evaluation and extension of the numerical results, drawn from the analysis, through system-level simulations. Our results show that, in scenarios with significant interference, the best throughput-delay tradeoff is achieved by single path forwarding. Moreover, when significant interference is present and network coding employs the larger packet generation size, it experiences higher delay than the other schemes. This is due to the inter-arrival times aggregating over all coded packets required to decode a packet generation. (C) 2015 Elsevier B.V. All rights reserved.

Funding Agencies|HERACLEITUS II - University of Crete

In this paper we consider random access wireless multi-hop mesh networks with multi-packet reception capabilities where multiple flows are forwarded to the gateways through node disjoint paths. We address the issue of aggregate throughputoptimal flow rate allocation with bounded delay guarantees. We propose a distributed flow rate allocation scheme that formulates flow rate allocation as an optimization problem and derive the conditions for non-convexity for an illustrative topology. We also employ a simple model for the average aggregate throughput achieved by all flows that captures both intra-and interpath interference. The proposed scheme is evaluated through NS-2 simulations. Our preliminary results are derived from a grid topology and show that the proposed flow allocation scheme slightly underestimates the average aggregate throughput observed in two simulated scenarios with two and three flows respectively. Moreover it achieves significantly higher average aggregate throughput than single path utilization in two different traffic scenarios examined.

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