Vector Coding Optical Wireless Links

The quasi-static nature of the optical wireless channel means that the channel state information (CSI) can be readily available at the transmitter and receiver prior to data transmission. This implies that electrically band-limited optical wireless communication (OWC) systems can make use of optimal channel partitioning or vector coding based multi-channel modulation (MCM) to achieve high throughput by mitigating the non-linearities arising from the optical and electrical channel. This paper proposes a pulse amplitude modulation (PAM) based DC-biased optical vector coding (DCO-VC) MCM scheme for OWC. The throughput performance of DCO-VC is evaluated and compared to the well known DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) over hybrid (line-of-sight and diffuse) and diffuse (non line-of-sight only) visible light communication (VLC) channels with additive white Gaussian noise. For the completeness of the VLC physical layer, the performance comparison is based on an uncoded and a forward error correction transmission mode using well-known convolutional codes with Viterbi decoder. The results show that the coded DCO-VC outperforms DCO-OFDM system by achieving up to 2 and 3 dB signal to noise ratio gains over hybrid and diffuse VLC channels, respectively

Pilot-aided estimation and equalisation of a Radio-over-Fibre system in Wideband Code Division Multiple Access

In this study, the impact of a Radio-over-Fibre (RoF) subsystem on the capacity performance of wideband code division multiple access is evaluated. This study investigates the use of pilot-aided channel estimation to compensate for the optical subsystem non-linearities for different channel conditions, estimation intervals and coding schemes. The results show that pilot-aided channel estimation is an effective method for compensating the composite impairments of the optical subsystem and the radio frequency (RF) channel. It is found that there is always a suitable pilot power level which maximises the system capacity performance regardless of coding scheme and channel condition. Also, the peak capacity is only slightly affected by a decrease in the estimation interval

5G innovation opportunities-- A discussion paper

On the shaping of 5G technologies and networks, scope for wider service and applications innovation and UK strengths and opportunities

Behavioural couples therapy for adult drug and alcohol users.

A guideline for behavioural couples therapy that aims to build support for abstinence and improve relationship functioning in married or co-habiting couples, where one member is seeking help for substance use. Treatment focuses on a “sobriety contract”, changing the reinforcement contingencies in the relationship, increasing positive activities and teaching communication skills. This can be delivered as a standalone intervention or as an adjunct to individual therapy. Settings: Community settings. Duration: Couple seen for 12–20 hourly sessions over a 3–6 month period

Dynamic cell expansion with self-organizing cooperation

This paper addresses the challenge of how to reduce the energy consumption of a multi-cell network under a dynamic traffic load. The body of investigation first shows that the energy reduction upper-bound for transmission improving techniques is hardware-limited, and the bound for infrastructure reduction is capacity-limited. The paper proposes a novel cell expansion technique, where the coverage area of cells can expand and contract based on the traffic load. This is accomplished by switching off low load cell-sites and compensating for the coverage loss by expanding the neighboring cells through antenna beam tilting. The multi-cell coordination is resolved by using either a centralized controller or a distributed self-organizing-network (SON) algorithm. The analysis demonstrates that the proposed distributed algorithm is able to exploit flexibility and performance uncertainty through reinforced learning and improves on the centralized solution. The combined energy saving benefit of the proposed techniques is up to 50% compared to a reference deployment and 44% compared with alternative state-of-the-art dynamic base-station techniques