Bangjiang Lin

Experimental Demonstration of IFDMA for Uplink Visible Light Communication

In this letter, we propose an experimental demonstration of uplink visible light communications based on interleaved frequency division multiple access (IFDMA) with high spectral and power efficiencies, low complexity of the transmitter, high tolerance against multipath-induced distortion, and synchronization error. We show that IFDMA with a lower peak-to-average power ratio offers improved bit error rate (BER) performance compared with the orthogonal frequency division multiplexing access. For the uplink, the increase in the transmission span is ~4 cm at a BER of 10-5.

Efficient frequency-domain channel equalisation methods for OFDM visible light communications

We present efficient frequency domain channel estimation methods based on the ISFA, MMSE and WIFA schemes for the orthogonal frequency division multiplexing (OFDM) visible light communications (VLC) system.

Experimental Demonstration of an Indoor VLC Positioning System Based on OFDMA

We propose an indoor visible light communications and positioning system using the orthogonal frequency division multiplexing access (OFDMA) scheme, which can provide both indoor positioning and communications.

Experimental Demonstration of OFDM/OQAM Transmission for Visible Light Communications

We propose a modified orthogonal frequency division multiplexing/offset quadrature amplitude modulation (OFDM/OQAM) scheme for visible light communications (VLC). The OFDM/OQAM VLC system can efficiently boost the data rate, and combat multipath induced the inter symbol interference (ISI) and inter carrier interference (ICI). To combat the effect of intrinsic imaginary interference, intrasymbol frequency-domain averaging and minimum mean squared error (MMSE), combined with interference approximation method, are proposed. The experiment results show that the proposed system offers similar bit error rate performance to that of OFDM, while the bit rate is increased by 9% for the elimination of cyclic-prefix and guard band.

Experimental demonstration of bidirectional NOMA-OFDMA visible light communications

We propose a non-orthogonal multiple access (NOMA) scheme combined with orthogonal frequency division multiplexing access (OFDMA) for visible light communications (VLC), which offers a high throughput, flexible bandwidth allocation and a higher system capacity for a larger number of users. Bidirectional NOMA-OFDMA VLC is experimentally demonstrated. The effects of power allocation and channel estimation on the bit error rate performance are investigated. The experiment results indicate that accurate channel estimation can eliminate the inter-user interference more effectively. The optimum power allocation ratios for uplink and downlink are both about 0.25 in the case of two users.

Experimental demonstration of interleave division multiple access visible light communication

Abstract. We propose an experimental demonstration of visible light communication (VLC) based on interleave division multiple access (IDMA), which offers low peak-to-average power ratio, low complexity, and high robustness against multiple access interference and burst error. Bidirectional IDMA-VLC transmission is experimentally demonstrated. The experiment results indicate that IDMA offers better bit error rate performance compared with orthogonal frequency-division multiplexing access.

Time-domain channel estimator for polarization interleaving direct-detection orthogonal frequency-division multiplexing passive optical network

We propose an efficient time-domain channel estimation method for polarization interleaving orthogonal frequency-division multiplexing passive optical network with direct detection. Compared with the frequency-domain least-square channel estimator and intrasymbol frequency-domain averaging, the time-domain channel estimator with overhead reduction demonstrates better system robustness against transmission impairments, such as optical noise, chromatic dispersion, and polarization mode dispersion.

Experimental demonstration of block interleaved frequency division multiple access for bidirectional visible light communications

Abstract. We propose a power efficient multiple access scheme for visible light communications (VLC) based on the block interleaved frequency division multiple access (B-IFDMA) which provides large frequency-diversity, flexible bandwidth allocation, low complexity of channel equalization, and user separation. Bidirectional B-IFDMA VLC transmission is experimentally demonstrated to verify its feasibility. The impact of the number of subcarriers per block on the transmission performance under wireless optical channel is investigated.

Experimental demonstration of multiple-inputs multiple-outputs OFDM/OQAM visible light communications

Abstract. We experimentally demonstrate a 2×2 optical multiple-inputs multiple-outputs (MIMO) visible light communications system based on the modified orthogonal frequency-division multiplexing/offset quadrature amplitude modulation scheme. The adjacent subcarrier frequency-domain averaging (ASFA) with the full-loaded (FL) and half-loaded (HL) preamble structures is proposed for demultiplexing and mitigating the intrinsic imaginary interference (IMI) effect. Compared with the conventional channel estimation (CE) method, ASFA offers improved transmission performance. With the FL method, we obtain more accurate MIMO CE to mitigate the IMI effect and the optical noise compared to the HL method.

Efficient frequency-domain channel equalisation methods for OFDM/OQAM-PON with intensity modulation and direct detection

In this study, the authors present efficient frequency-domain channel estimation (CE) methods based on the adjacent subcarriers frequency-domain averaging (ASFA) and minimum mean squared error (MMSE) schemes for the orthogonal frequency division multiplexing/offset quadrature amplitude modulation (OFDM/OQAM) passive optical network (PON) system. The complete channel transmission response for OFDM/OQAM-PON with the chromatic dispersion induced intrinsic imaginary interference effect is systemically derived. Compared with the conventional interference approximation CE method, ASFA and MMSE offer improved receiver sensitivity.