Anahtar kelimeler Enerji verimliliği; PSM; IEEE 802.11 Kablosuz ağları; Ağ Erişim Kontrolü; CSMA/CA

IEEE 802.11 kablosuz ağları sağladığı esneklik, uygun fiyatlandırma ve kolay kurulum avantajları ile akıllı cihazlar tarafından günümüzde en çok kullanılan kablosuz ağ erişim teknolojilerinden biri haline gelmiştir. Yalnız kablosuz bir ağ arayüzünün akıllı cihazlarda aktif olarak kullanılması, bataryanın hızlı tüketimine ve etkin kullanım süresinin önemli derecede azalmasına sebep olmaktadır. IEEE 802.11 kablosuz ağ standardları (IEEE 802.11a/b/g/n/ac) kullanıcıların ağa erişiminde Çarpışmadan Kaçınmalı Taşıyıcı Duyarlı Çoklu Erişim (Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)) yaklaşımını kullanmaktadır. Bu yaklaşım cihazlar arası paket gönderim işlemlerinin çarpışmaması için ağın dinlenmesine dayanır. Bu dinleme işlemi sırasında cihazlar önemli derecede güç tüketirler. Bu sorunun çözümü için kablosuz ağ standardında tanımlanan Güç-Tasarruf-Modu (PSM) kulanılabilir. Kablosuz ağ standardında bu kısım tanımlansa da, kabul edilen herhangi bir standard algoritma bulunmamaktadır. Dolayısıyla, optimal enerji verimliliği için literatürde sunulan bir çok PSM temelli yaklaşım mevcuttur. Bu çalışma kapsamında öncelikle literatürde sunulan ve PSM protokolünü etkin kullanan güncel PSM önerileri incelenmektedir. Sonrasında ise bahsi geçen öneriler OMNET benzetim ortamına aktarılarak enerji verimliliği mukayese edilmektedir.

Energy-efficient IEEE 802.11 PSM Approaches and Their Comparison

IEEE 802.11 wireless networking technology is now one of the most utilized Radio Access Technologies (RAT) as it provides mobility, low cost and easy deployment. However, activating Wi-Fi interface of a smart mobile device causes reduction on active use-time of the battery with rapid power consumption. IEEE 802.11 wireless network standards let devices perform Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) to access the channel. This method is based on sensing the medium and scheduling channel access to reduce probability of collision. Yet, it results in high amount of power consumption. In order to address this problem, Power Save Mode (PSM) has been declared in the amendment, but procedure of the PSM left open to researchers. Therefore, there have been many PSM-based energy-efficient channel access approaches proposed in the literature. Throughout this paper, we first examine existing well-performed state of the art PSM approaches. Second, we evaluate and compare energy efficiency ratios of these approaches via OMNET network simulator.

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