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In light of the growing disparit y between residential broadband and 802.11 speeds, Access Point (AP) backhaul aggre gation has been proposed b y the research communit y as a service whereb y residential customers ma y enjo y higher throughput when in range of participating 802.11 APs. The fundamental assumption of these works is that 802.11 clients can be modified at driver level. However, due to the high diversit y of 802.11 chipsets and drivers in the market, the cost of modif y ing an y WiFi driver for an y operating s y stem is prohibitive, which in turn makes the solution unpractical for commercial deplo y ment. In this paper, we propose a WLAN backhaul aggregation scheme that works with unmodified 802.11 clients. We introduce SmartAP, a single-radio 802.11 AP, that can deliver higher throughput to its off-the-shelf clients b y aggregating the backhaul capacit y of APs in range, even if these APs are in different radio channels. SmartAP reaches this goal without adding new radio hardware to the network.We build SmartAP with off-the-shelf hardware and evaluate its performance in a network testbed of 6-nodes with unmodified smartphones and laptops as clients. We evaluate the conditions under which SmartAP leads to gains comparable to state-of-the art approaches with client-side modifications and we demonstrate that using a two-hop transmission to access additional backhaul capacit y y ields substantial benefits.

The high bandwidth demand of Internet applications has recently driven the need of increasing the residential download speed. A practical solution to the problem has been proposed aggregating the bandwidth of 802.11 Access Points (APs) backhauls in range via 802.11 connections. Since 802.11 devices are usually single-radio, the communication to multiple APs on different radio-channels requires the introduction of a time-division multiple access (TDMA) policy at the client station. Current investigation in this area supposes that there is a sufficient number of TCP flows to saturate the Asymmetric Digital Subscriber Line (ADSL) behind the APs. However, this may be not guaranteed according to the user traffic pattern. As a consequence, a TDMA policy introduces additional delays in the end-to-end transmissions that will cause degradation of the TCP throughput and an under-utilization of the AP backhauls. In this paper, we first perform an in-depth experimental analysis with a customized 802.11 driver of how the usage of multi-AP TDMA affects the observed Round-Trip-Time (RTT) of TCP flows.Then, we introduce a simple analytical model that accurately predicts the TCP RTT when accessing the wireless medium with a Multi-AP TDMA policy. Based on this model, we propose a resource allocation algorithm that runs locally at the station and it greatly reduces the observed TCP RTT with a very low computational cost. Our proposed scheme can improve up to 1.5 times the aggregate throughput observed by the station compared to state-of-the-art multi-AP TDMA allocations. We also show that the throughput performance of the algorithm is very close to the theoretical upper-bound in key simulation scenarios.

Access networks include modems, home gateways, and DSL Access Multiplexers (DSLAMs), and are responsible for 70-80% of total network-based energy consumption. In this paper, we take an in-depth look at the problem of greening access networks, identify root problems, and propose practical solutions for their user-and ISP-parts. On the user side, the combination of continuous light traffic and lack of alternative paths condemns gateways to being powered most of the time despite having Sleep-on-Idle (SoI) capabilities. To address this, we introduce Broadband Hitch-Hiking (BH 2 ), that takes advantage of the overlap of wireless networks to aggregate user traffic in as few gateways as possible. In current urban settings BH 2 can power off 65-90% of gateways. Powering off gateways permits the remaining ones to synchronize at higher speeds due to reduced crosstalk from having fewer active lines. Our tests reveal speedup up to 25%. On the ISP side, we propose introducing simple inexpensive switches at the distribution frame for batching active lines to a subset of cards letting the remaining ones sleep. Overall, our results show an 80% energy savings margin in access networks. The combination of BH 2 and switching gets close to this margin, saving 66% on average.

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