This paper develops a receiver structure to perform jointly ML synchronisation, equalisation and detection of a linearly modulated signal transmitted over a time-varying, frequency-selective, Rician faded channel, corrupted by AWGN. The receiver is particularly suited to a fast fading channel, where other receivers that rely on estimating the channel cannot track it quickly enough. The signal mean and autocovariance are needed, and a scheme is proposed for estimating these quantities adaptively. The receiver processes the specular and diffuse components (corresponding to the signal mean and autocovariance) separately. Processing the known specular component is the classical detection problem. The unknown diffuse component is processed by predictors [11]. We show that the predictors can achieve synchronisation in a novel manner, if synchronisation is required. A union bound on the receiver's BER is derived, and it tightly bounds simulated BERs in fast fading at high SNRs.
In this paper, we investigate the problem of channel bounding in wireless local area networks (WLANs). We propose a MAC protection mechanism to combat the hidden node problem on non-primary channels of a basic service set (BSS). Simulation results show that the proposed MAC protection mechanism is effective in combating hidden nodes and improving throughput of 80MHz stations. The proposed scheme has been adopted into the IEEE 802.11ac specification as a mandatory feature [3]. Furthermore, we extend the medium access mechanisms defined in 802.11n for a wider bandwidth, evaluate fairness of the 802.11n PIFS medium access mechanisms, and compare the performance of a dynamic bandwidth scheme with that of a static bandwidth implementation.
In 2013, global mobile data traffic grew 81% and it is projected to increase 11-fold between 2013 and 2018. Further, it is predicted that by 2018, over two-thirds of the world's mobile traffic will be video and more than half of all traffic from wireless connected devices will be offloaded to Wi-Fi networks and femto-cells [1]. Consequently, wireless LANs need major upgrades to improve both throughput and efficiency. IEEE 802.11ac is an amendment to the 802.11 standard that was just ratified by IEEE 802.11. Promising up to gigabit data rates, many Wi-Fi products are being built based on this specification. In addition to technologies that improve throughput, IEEE 802.11ax is investigating and evaluating advanced wireless technologies that enable more efficient utilization of the existing spectrum.
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