VoIPiggy: Implementation and evaluation of a mechanism to boost voice capacity in 802.11 WLANs

This work is at: The 31st Annual IEEE International Conference on Computer Communications (IEEE INFOCOM 2012), took place March 25-30, 2012 in Orlando, Florida, USA.Supporting voice traffic in existing WLANs results extremely inefficient, given the large overheads of the protocol operation and the need to prioritize this traffic over, e.g., bulky transfers. In this paper we propose a simple scheme to improve the efficiency of WLANs when voice traffic is present. The mechanism is based on piggybacking voice frames over the acknowledgments, which reduces both frame overheads and time spent in contentions. We evaluate its performance in a large-scale testbed consisting on 33 commercial off-the-shelf devices. The experimental results show dramatic performance improvements in both voice-only and mixed voice-and-data scenarios.The research leading to these results was funded by the EU’s Seventh Framework Programme (FP7-ICT-2009-5) under grant agreement n.257263 (FLAVIA) and by the the Spanish Ministry of Science and Innovation under grant TEC2010- 10440-E. It was supported in part by the MEDIANET Project (grant S2009/TIC-1468) from the General Directorate of Universities and Research of the Regional Government of Madrid.Publicad

Evaluating MPEG-4/AVC Video Streaming over IEEE 802.11 Wireless Distribution System

Abstract—The high cost of rewiring existing houses with Ethernet to support broadband home networks has motivated consumers and service providers for “no-new-wires ” and “no-wires ” technologies. IEEE 802.11 wireless LAN is preferred due to its flexibility and affordability, but the achievable coverage and data rate are still very limited in a household environment due to high attenuation and interference. In this paper, we evaluate the performance of MPEG-4 AVC video streaming over IEEE 802.11 Wireless Distribution System (WDS), which is often used to increase wireless coverage for data applications. Our results show that by properly adjusting wireless transmission power and rate, it is possible to increase the coverage and performance at the same time, which allows broadband applications such as IPTV to be delivered in multiple hops across house. Index Terms—Video streaming, MPEG-4, IEEE 802.11, WDS I

Performance Analysis of VoIP Using WiMAX, LTE and WLAN Mobile Networks

Prijenos govora preko Internet protokola je usluga koja ima sve veću primjenu kod korisnika. Kako je govor usluga koja se odvija u stvarnom vremenu njena kvaliteta je izrazito važna. Kritični parametri kvalitete ove usluge su: kašnjenje, jitter, gubitak paketa i propusnost. Ovisno o vrsti mreže koja se koristi za prijenos govora variraju iznosi ovih parametara odnosno kvaliteta usluge. Analizirani su kritični parametri kvalitete usluge VoIP (jitter, kašnjenje, gubitak paketa) za tri različite mreže: WLAN, LTE i WiMAX, te su utvrđene performanse ove usluge za te mreže.Voice over Internet protocol is a service that has been increasingly used by the user. As speech being a real-time service it's quality is extremely important. Critical parameters of the quality of service are: delay, jitter, packet loss and throughput. Depending on the type of network used for voice transmission the amount of these parameters varies that is the quality of service varies. Critical parameters of quality of service for VoIP (jitter, delay, packet loss) were analyzed in three different networks: WLAN, LTE and WiMAX, and the performance of the service for these networks is determined