Joint Space-Time Block-Coding and Beamforming for the Multiuser Radio Over Plastic Fiber Downlink

Abstract

Abstract-An all-optical processing aided multi-functional wireless Multiple-Input-Multiple-Output (MIMO) architecture is designed, where both diversity and beamforming gains can be attained. Explicitly, we propose an architecture, where the twin-antenna Alamouti space-time block coded symbols are transmitted using a single Mach-Zenhder Modulator (MZM) over a plastic optical fiber. The signal is then transmitted through a set of Fiber Bragg Gratings (FBGs) for attaining the appropriate phase shifts for beamforming, followed by transmission over the wireless channel. The attainable angular beamsteering range is about 150• , where beamsteering is realized without the need for a large number of complex electronic phase shifter networks. The tuning of the beamsteering angle can be readily implemented by carefully controlling the drive voltage in the Mach-Zenhder Modulator, where we use MZM aided multi-wavelength generation for supporting a large number of antennas.

Analog Radio-over-Fiber-Aided Optical-Domain MIMO Signal Processing for High-Performance Low-Cost Radio Access Networks

“…Therefore, A-RoF is only suitable for short-length (e.g, < 20 km) fiber-based radio access networks. Therefore, A-RoF techniques have been primarily used in millimeterWave (mmWave) [12] C-RAN systems [4] and in indoor LANs [11] for short-range transmission using plastic optical fiber [12]. But, again, A-RoF and MIMOs may be beneficially amalgamated into a cost-efficient highperformance centralised system, hence we focus our attention on A-RoF aided MIMO assisted RANs.…”

“…2, the optical-domain MIMO signal processing can be performed by exploiting carrier modulation and E/O conversion, where the multi-stream MIMO concept can be implemented in the optical domain either by optical sideband selection for feeding the activated antennas of the popular spatial modulation (SM) scheme [4]. Alternatively, fiber Bragg grating (FBG) may be used for true time-delay based beamforming [12] or optical filter banks may be employed for appropriately mapping the space-time-block-coding symbols to the corresponding antennas for achieving a beneficial transmit diversity gain [12]. The above-mentioned techniques are capable of totally eliminating the electronic MIMO signal processing.…”

Analogue Radio Over Fiber Aided MIMO Design for the Learning Assisted Adaptive C-RAN Downlink

“…The number of controllable drive frequency is linked to the number of SM antennas, where K drive frequencies can be used for mapping the data to 2 × K th pair of STBC transmit antennas, facilitating our arbitrary number of antenna design. In our system, we use a flexible TFG, which is evolved from our previously proposed TFG of [10]. As shown in Fig.…”

“…Moreover, by exploiting the fiber's low antenuation, its substantial bandwidth and its immunity to electro-magnetic interference [8], the A-RoF based C-RAN system is capable of simplifying the functions of the RRHs, since both the modulation as well as the analogue-to-digital conversion (ADC) and digital-to-analogue conversion (DAC) operations are carried out by the CU, while the passive optical processing components and antennas used at the RRHs only impose a modest cost [5], [9]. This results in an energy-efficient mobile access network relying on centralised MIMO schemes [10].…”

Analogue Wireless Beamforming Exploiting the Fiber-Nonlinearity of Radio Over Fiber-Based C-<roman>RANs</roman>

“…On the other hand, we invoke a cloud radio access network (C-RAN) [5], [6], where a central office housing the centralized baseband signal processing [7] serves multiple lowcomplexity and low-cost remote radio heads (RRHs). The proposed C-RAN [8] invokes Radio over Fiber (RoF) [9] transmissions to the RRHs for supporting the emerging smallcell technologies [8].…”