On the evaluation of the IEEE 802.11ac WLAN performance with QoS deployment

The increase in the number of users on wireless local area networks (WLAN) and the development of large size applications have increased the demand for high-speed data rate and low latency. The IEEE 802.11ac was developed to provide very high throughput WLANs. Many enhancements are added to the medium access control (MAC) and physical (PHY) layers to increase data rate and improve network performance, these features enable the IEEE 802.11ac standard to provide quality of service (QoS) for multimedia applications. This paper concentrates on the impact of QoS on the system performance in term of delay and throughput. Four scenarios are proposed to investigate the network performance with different (from 1 up to 8) spatial stream (SS). The objective modular network testbed in C++ (OMNet++ modeler v5.5.1) is used to simulate and model these scenarios. For 8×8 SS, the results of simulation show the best throughput (maximum) and delay (minimum) values of (622, 484, 399.3, 382.96 Mbps) and (0.0211, 0.0589, 0.1037, 0.1202 sec) for 5, 15, 30 and 45 node number scenarios respectively. Although the number of nodes increases, the system performance decreases, however when QoS is deployed the performance is enhanced and its best improvement is obtained at the highest (45) node number scenario with values of 94.4% and 56.1% for throughput and delay respectively.

Autotransporta bezvadu sakaru tīklu veiktspējas pētīšana un tās paaugstināšana

Globālās attīstības tendences – automobiļu skaita pieaugums, viedo ierīču ar bezvadu tīkla savienojumu skaita palielināšanās un pārraidāmās informācijas apjoma straujais pieaugums – veicina pieprasījumu pēc lielāka datu apmaiņas ātruma, mobilitātes un augstāka savienojamības līmeņa. Tādējādi tiek pieprasīti datu pārraides pakalpojumi arī tādos gadījumos, kad lietotāji pārvietojas ar autotransportu. Pieaugot automobiļu skaitam, jārisina arī problēmas, kas ir saistītas ar drošību uz ceļiem un transporta plūsmu vadību. Šīs problēmas akcentē nepieciešamību pēc mūsdienīgiem, tehniski un ekonomiski pamatotiem intelektuālo transporta sistēmu (ITS) sakaru risinājumiem. Viena no bezvadu tīklu tehnoloģijām, ko var izmantot ITS, konkrēti – automobiļu pasažieru, vajadzību nodrošināšanai ar piekļuvi datu pārraides tīklam, ir WLAN IEEE 802.11n/ac. Realizējot šādus WLAN bāzētus automobiļu bezvadu sakaru piekļuves tīklus, ir jārisina vairāki jautājumi, kas galvenokārt ir saistīti ar ātri kustīgiem objektiem. Praksē izmantojams ir divrangu bezvadu sakaru tīkls, kas var nodrošināt piekļuvi internetam. Promocijas darbā izveidotas un izpētītas vairākas divrangu autotransporta sakaru tīkla testgultnes, izmantojot WLAN IEEE 802.11n un LTE tehnoloģijas. Eksperimentāli novērtēts, kā mainās datu trafika raksturlielumi divrangu sakaru tīklā, izmantojot dažādu ražotāju LTE aparatūru. Pētīta šādu hibrīdu sakaru kanālu veiktspēja atkarībā no mobilo klientu pārvietošanās ātruma, klientu skaita un izmantotajiem kustības scenārijiem. Iegūtas jaunas integrētu IEEE 802.11n un LTE autotransporta sakaru tīklu veiktspēju raksturojošas likumsakarības, kas apraksta tīkla caurlaidspējas atkarību no mobilā klienta pārvietošanās ātruma. Promocijas darbā izveidota un izpētīta arī vienranga autotransporta sakaru testgultne, kas bāzēta IEEE 802.11ac tehnoloģijā. Pētījumā izstrādāts un realizēts uzlabots IEEE 802.11v standartā bāzēts pārslēgšanās procedūras (angļu val. handover) algoritms. Šādam vienranga automobiļu sakaru tīklam teorētiski novērtētas veiktspēju raksturojošas likumsakarības.

Measurement Study of Real-Time Virtual Reality Contents Streaming over IEEE 802.11ac Wireless Links

Experience sharing among multiple users in virtual reality (VR) is one of the key applications in next generation wireless systems. In this VR application, one object can be reproduced as a virtual object based on recorded/captured multiple real-time images from multiple observation points. At this time, VR applications require a lot of bandwidth to provide seamless services to users in wireless links, and thus, a certain level of data rates should be maintained. As the number of users increases, the server allocates more data rates to users on top of the limited bandwidth in wireless networks. At this time, users who utilize the VR streaming services will suffer from a lower quality, due to the limited bandwidth. This paper reports the measurement study and also analyzes the fluctuations in terms of the data rates as the number of users increases while sharing point cloud information in real-time authorized reality environments over IEEE 802.11ac wireless networks. Moreover, it measures and analyzes fluctuations in terms of frames-per-second and Jitters, which are practical quality reduction indicators.

Analysis for Modulation and Coding Scheme with Data Rate Traffic Over IEEE 802.11AC and 802.11N in Wireless Multimedia

This paper discusses wireless traffic consisting of various types of data packets. Regardless of the type of data being sent and received, the transmission can suffer from latency problems. The wireless multimedia standard enables the service provider to prioritize voice, video, best-effort, and background data by adding differentiated services code point value to the internet protocol header. This effectively allows network users to benefit from optimal network performance while using various applications with different latency and throughput requirements. In this paper, we conducted a study of five use-cases over two common wireless standards, IEEE 802.11n and IEEE 802.11ac. The study was carried out by prioritizing, respectively, voice, video data packets, with lowest priority assigned to best-effort data packets. The best-effort traffic can have more bandwidth than the voice or video. Under each use case, we evaluated the impact of additional network load on video streaming.