Belaidžio ryšio tinklų terpės prieigos valdymo tyrimas

Over the years, consumer requirements for Quality of Service (QoS) has been growing exponentially. Recently, the ratification process of newly IEEE 802.11ad amendment to IEEE 802.11 was finished. The IEEE 802.11ad is the newly con-sumer wireless communication approach, which will gain high spot on the 5G evolution. Major players in wireless market, such as Qualcomm already are inte-grating solutions from unlicensed band, like IEEE 802.11ac, IEEE 802.11ad into their architecture of LTE PRO (the next evolutionary step for 5G networking) (Qualcomm 2013; Parker et al. 2015). As the demand is growing both in enter-prise wireless networking and home consumer markets. Consumers started to no-tice the performance degradation due to overcrowded unlicensed bands. The un-licensed bands such as 2.4 GHz, 5 GHz are widely used for up-to-date IEEE 802.11n/ac technologies with upcoming IEEE 802.11ax. However, overusage of the available frequency leads to severe interference issue and consequences in to-tal system performance degradation, currently existing wireless medium access method can not sustain the increasing intereference and thus wireless needs a new methods of wireless medium access. The main focal point of this dissertation is to improve wireless performance in dense wireless networks. In dissertation both the conceptual and multi-band wireless medium access methods are considered both from theoretical point of view and experimental usage. The introduction chapter presents the investigated problem and it’s objects of research as well as importance of dissertation and it’s scientific novelty in the unlicensed wireless field. Chapter 1 revises used literature. Existing and up-to-date state-of-the-art so-lution are reviewed, evaluated and key point advantages and disadvantages are analyzed. Conclusions are drawn at the end of the chapter. Chapter 2 describes theoretical analysis of wireless medium access protocols and the new wireless medium access method. During analysis theoretical simula-tions are performed. Conclusions are drawn at the end of the chapter. Chapter 3 is focused on the experimental components evaluation for multi-band system, which would be in line with theoretical concept investigations. The experimental results, showed that components of multi-band system can gain sig-nificant performance increase when compared to the existing IEEE 802.11n/ac wireless systems. General conclusions are drawn after analysis of measurement results

TCP performance in multi-polling game theory-based IEEE 802.11 networks

Easy usage and integration with various applications made IEEE 802.11 one of the most used technologies these days, both at home and business premises. Over the years, there have been many additional improvements to the 802.11 standards. Nevertheless, the algorithms and Media Access Control (MAC) layer methods are almost the same as in previous Wi-Fi versions. In this paper, a set of methods to improve the total system capacity is proposed – such as efficient transmit power management based on Game Theory with a custom wireless medium protocol. The transmit power management and wireless medium protocol is verified by both simulation and real application scenarios. The results conclude that the capacity of theproposed wireless medium protocol is overall 20 percent higher than the standard 802.11 wireless medium access protocols. Additional TCP Acknowledgment filtering, which was tested together with the proposed wireless medium access protocol, can provide up to 10-percent-higher TCP throughput in high-density scenarios, especially for asymmetrical traffic cases. The conducted research suggests that efficient power management could result in lighter transmit power allocation rules that are currently set by the local regulators for current Wi-Fi devices. Thus, better propagation characteristics and wireless medium management would lead to an overall higher wireless system capacity

A New Game for Future Wi-Fi Spectrum Sharing

This article offers a vision for moving on from the paradigm of "constrained politeness" that has long governed Wi-Fi access to a shared spectrum – as embodied by the CSMA/CA mechanism and restricted EIRP limits. Instead, it is proposed to embrace a paradigm of a "cooperative game" where quasi-cognitive devices establish by themselves a mutually collaborative spectrum coexistence community, based on a unified set of simple rules, which operates on the basis of balancing individual transmits powers as a function of overall noise environment. It is shown that the proposed new mode of spectrum access, results in a significantly increased overall spectrum use efficiency, defined in terms of aggregate throughput carried in given bandwidth by a populace of devices over unit area. Most importantly, the new spectrum access would be still implicitly suitable for the Wi-Fi ethos of self-management and uncoordinated deployment. The proposed method, supported by both theoretical and practical simulations, represents one of the first practical implementations that prove feasibility and usefulness of Game Theory to the practice of wireless communications

Applying game theory in 802.11 wireless networks / Žaidimų teorijos taikymas IEEE 802.11 tinkluose

IEEE 802.11 is one of the most popular wireless technologies in recent days. Due to easiness of adaption and relatively low cost the demand for IEEE 802.11 devices is increasing exponentially. IEEE works in two bands 2.4 GHz and 5 GHz, these bands are known as ISM band. The unlicensed bands are managed by authority which set simple rules to follow when using unlicensed bands, the rules includes requirements as maximum power, out-of-band emissions control as well as interference mitigation. However these rules became outdated as IEEE 802.11 technology is emerging and evolving in hours the rules aren’t well suited for current capabilities of IEEE 802.11 devices. In this article we present game theory based algorithm for IEEE 802.11 wireless devices, we will show that by using game theory it’s possible to achieve better usage of unlicensed spectrum as well as partially decline CSMA/CA. Finally by using this approach we might relax the currently applied maximum power rules for ISM bands, which enable IEEE 802.11 to work on longer distance and have better propagation characteristics. Santrauka  Lengvai pritaikoma ir panaudojama įvairiuose sprendimuose IEEE 802.11 technologija tapo viena populiariausių bevielių technologijų. IEEE 802.11 įrenginiai veikia nelicencijuotais 5 GHz ir 2,4 GHz dažniais – pramonės, mokslo ir medicinos dažnių ruože (angl. Industrial, scientific and medical (ISM) radio bands). Šiam dažnių ruožui taikomos supaprastintos taisyklės, nurodančios, kad įrenginiai, veikiantys ISM dažniais, turi atitikti tik maksimalią signalo perdavimo galią ir interferencijos triukšmus bei neviršyti triukšmo normos už dažnių ruožo ribų. Tobulėjant IEEE 802.11 protokolo įrangai, šios taisyklės tapo nelanksčios ir neatitinka dabartinių įrenginių galimybių. Straipsnyje pristatomas naujas IEEE 802.11 įrenginių kanalo prieigos metodas, pagrįstas žaidimų teorija. Parodoma, kad taikant šį metodą galima pagerinti spektro panaudojimo efektyvumą bei kartu iš dalies atsisakyti dabar egzistuojančio CSMA/CA mechanizmo IEEE 802.11 įrenginiuose. Taikant efektyvesnį kanalo prieigos metodą atsiranda galimybė laikytis lankstesnių siųstuvo galių taisyklių ir taip padidinti skvarbą uždarose patalpose bei įrangos veikimo nuotolį. Raktiniai žodžiai: IEEE 802.11, WiFi, interferencija, kognityvusis radijas, žaidimų teorija

TCP Performance in Multi-Polling Game Theory based IEEE 802.11 networks

Easy usage and integration with various applications made IEEE 802.11 one of the most used technologies these days, both at home and business premises [1]. Over the years, there have been additional improvements to 802.11 standards. The very first important mechanism, which added additional performance gains, was frame aggregation and block-acknowledgements (block-acks). However, this still does not provide good efficiency, thus we can see various performance problems in dense wireless networks. One of the many problems is TCP performance degradation due to delayed acknowledgement transmissions and the overall handling of medium acquisition. Newly introduced version of IEEE 802.11ac brought some important performance updates such as additional modulation capabilities or interference mitigation. Nevertheless, the principals and Media Access Control (MAC) layer methods are almost the same as in previous Wi-Fi versions. Therefore, a more efficient MAC layer protocol would add additional benefit for newly released IEEE 802.11ac and currently existing IEEE 802.11n standards. In this paper, we will do a case study of IEEE 802.11e Hybrid Carrier Sense Multiple Access Collision Avoidance (CSMA/CA) and Polling Mechanism. We will consider various methods to bypass the limitations of already existing CSMA/CA protocol as well as polling based protocols. Additionally, we will introduce the arising problems and currently available implementations of IEEE 802.11 improvements for TCP performance