Abstract
In this paper, interference mitigation techniques based on angle diversity receivers (ADRs) are studied for optical attocell networks. Consisting of multiple photodiodes (PDs), an ADR requires appropriate signal combining schemes in order to mitigate intercell interference (ICI) in optical attocell networks. Four signal combining schemes, namely select best combining, equal gain combining, maximum ratio combining, and optimum combining are investigated. To further mitigate ICI, a novel double-source cell configuration with two transmission modes is also proposed. Results show that the systems with ADRs significantly outperform those with single-PD receivers in terms of signal-to-interference-plus-noise ratio (SINR). Also, compared to the conventional single-source cell configuration, the double-source cell configuration can provide an SINR improvement of over $\text{20}$ dB. Furthermore, an analytical framework is proposed to analyze the performance of optical attocell networks with ADRs, where different propagation scenarios such as line-of-sight and nonline-of-sight are considered. The accuracy of the proposed analytical model is validated by Monte Carlo simulations.
Highlights
I N RECENT years, the number of mobile devices in use has increased tremendously
The electrical signal received by PD p is expressed in (1) [20], where the optical-to-electric conversion efficiency is denoted by τ ; ad is the index of the desired access points (APs); had,p (t) is the channel impulse response between AP ad and PD p; ha,p (t) is the channel impulse response between AP a and PD p; sa (t) is the instantaneous power transmitted by AP a; the noise power at the receiver is denoted by nrx (t); ⊗ is a convolution operator
This paper investigates interference mitigation techniques for indoor optical attocell networks with angle diversity receivers (ADRs)
Summary
I N RECENT years, the number of mobile devices in use has increased tremendously. As predicted in the latest Cisco Visual Networking Index (VNI), global mobile data traffic is expected to reach 24.3 exabytes per month by 2019 [1]. Optical attocell networks can offer several advantages over conventional RF cellular networks, their performance is still limited by ICI especially at cell-edge areas. In [12], a space division multiple access (SDMA) scheme using angle diversity transmitters was proposed This method can mitigate ICI by generating concentrated light beams to users at different positions. ICI can be reduced by adding PDs on an optical receiver, especially when these PDs have different directions This is because: i) with a fixed overall coverage area, the FOV of each PD becomes narrower as the number of PDs increases.
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