Timo Nihtilä

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The IEEE 802.11ac is an emerging very high throughput (VHT) WLAN standard, targeted to achieve data rates of close to 7 Gbps for the 5 GHz band. In this paper, we introduce the key mandatory and optional PHY features, as well as the MAC enhancements of 802.11ac over the existing 802.11n standard in the evolution towards higher data rates. Through numerical(More)
This paper presents the system performance analysis of 3GPP Long-Term Evolution (LTE) and IEEE 802.11 Wireless Local Area Networks (WLAN) in a situation where LTE downlink (DL) has been expanded over to unlicensed frequency band usually used by WLAN. Simple fractional bandwidth sharing mechanism is used to allow both technologies to transmit. The system(More)
This paper presents a performance evaluation of an uplink load balancing algorithm for Long-Term Evolution (LTE) Self-Organizing Networks (SON) in a non-regular network layout and shows how cell sizes affect the performance of the algorithm. The proposed algorithm solves local overload situations by handing over users to neighboring cells and adjusting(More)
The aim of this paper is to evaluate how Discontinuous Reception (DRX) cycles and related timers take effect to Voice over IP (VoIP) performance when High Speed Downlink Packet Access (HSDPA) networks are in question. DRX cycles limit the scheduling freedom of users and increase battery saving opportunities in the User Equipment (UE) by allowing it to turn(More)
Recently, the IEEE 802.11 standard based Wireless Local Area Networks (WLAN) have become more popular and are widely deployed. It is anticipated that WLAN will play an important rule in the future wireless communication systems in order to provide several gigabits data rate. IEEE 802.11ac is one of the ongoing WLAN standard aiming to support very high(More)