Self-organising interference coordination in optical wireless networks
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RESEARCH
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Self-organising interference coordination in optical wireless networks Birendra Ghimire1* and Harald Haas1,2
Abstract In this article, self-organising interference management for optical wireless networks deployed inside an aircraft cabin is investigated. A user that has received data in a given frame and intends to continue receiving data in the next frame broadcasts a busy burst (BB) in a time-multiplexed BB slot. The tagged access point (AP) intending to reuse a resource reserved in a neighbouring cell must listen to the BB slot. Provided that channel reciprocity holds, the tagged AP infers (prior to transmission) the amount of co-channel interference (CCI) potentially caused towards the victim user in neighbouring cell. This is a vital information for an AP to decide without any central supervision whether to transmit or defer the transmission to another time or frequency slot so as to limit CCI caused to the active link to a threshold value. Simulation results demonstrate that the BB approach significantly improves both fairness and spectral efficiency in the system compared to a static resource partitioning approach. 1. Introduction Data transmission using optical wireless has been identified as a technology that can be utilised for communications in critical environments, such as aircrafts or hospitals, where radio frequency (RF)-based transmissions are usually prohibited or refrained to avoid interference with critical systems. Moreover, a huge amount of unregulated bandwidth is available at infra-red and visible light frequencies. Likewise, optical wireless signals can be confined within a room which inherently addresses concerns over the eavesdropping of data. In addition, commercially available light emitting diodes (LEDs) and photodiodes (PDs) can be utilised for data transmission and reception. Therefore, there has been a considerable interest in utilising the frequencies at the infra-red and visible spectrum for data transmission [1-7]. The state-of-the-art technique [7] that utilises on-off keying (OOK) for transmitting data using visible light is rather inflexible when it comes to sharing bandwidth among multiple competing users served by an AP that have variable rate requirements. The above shortcoming is addressed by utilising optical intensity modulation (IM)/direct detection (DD) orthogonal frequency * Correspondence: [email protected] 1 School of Engineering and Science, Jacobs University Bremen, 28759, Bremen, Germany Full list of author information is available at the end of the article
division multiplexing (OFDM) for data communication. Using OFDM technique [8,9], the available bandwidth can be shared among multiple users by assigning each user a different amount of bandwidth corresponding to the user demand and the scheduling policies. Likewise, link adaptation can be carried out to scale the user throughput according to the prevalent channel conditions at the receiver. The composite baseband signal is modulated onto the optical carrier by varying the optical po
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