University of Twente Student Theses


Directional spectrum sensing in 6GHZ

Kalyankumar, M.K. (2021) Directional spectrum sensing in 6GHZ.

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Abstract:The growing demand for unlicensed spectrum has prompted policymakers to allow unlicensed access in the 6 GHz bands. Various Radio Access Technologies (RATs) such as WiFi and rapidly emerging 5G networks can operate in the unlicensed spectrum. To coexist harmoniously with each other, RATs must implement coexistence mechanisms such as Listen Before Talk (LBT). Omnidirectional-LBT (Omni-LBT) and Directional-LBT (Dir-LBT) are two LBT sensing techniques. Omni-LBT might fall short of identifying spectrum holes when the transmission is directional, while spatial reuse of the spectrum can be exploited using Dir-LBT. To find these spatial spectrum holes, more time is spent which leaves behind less time for data transmission. On the other hand, if less time is spent on sensing, sensing accuracy is affected. Therefore, using Dir-LBT might lead to a sensing-capacity trade-off. This thesis extensively investigates the trade-off between Omni-LBT/Dir-LBT. The sensing accuracy is calculated by formulating closed-form equations for the detection probability and false alarm probability. On plotting the closed-form equations, we conclude that Omni-LBT has a higher false alarm probability than Dir-LBT. As a result, the possibility to reuse the spectrum decreases, resulting in lower throughput and sensing accuracy than Dir-LBT. However, using Dir-LBT might lead to high sensing overhead. Therefore, it is essential to spend less time on sensing without hampering sensing accuracy. Towards this, we design a heuristic algorithm to reduce the sensing time of Generation Node-B (gNB). Finally, for the proposed heuristic algorithm, the throughput of gNB and Wireless Fidelity (WiFi-AP) were calculated and compared with Omni-LBT and our baseline algorithm. On simulating the values obtained, it becomes clear that Dir-LBT is better than Omni-LBT in terms of throughput.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:05 communication studies
Programme:Electrical Engineering MSc (60353)
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