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Base station sleep mode is an effective method to reduce the energy consumption of cellular networks. Taking into account a cellular network, its central base station (BS) can turn into sleep mode when the traffic is low and the users in this cell can access to neighbor active cells. A user offloading algorithm for the sleeping cell is investigated. The energy consumption of the cellular network in...
We experimentally demonstrate a 36-Gb/s DMT signal transmission over 50-km SSMF based on a cost-effective 10-GHz DML-based IM/DD system. The data rate is improved by 22% with Volterra filtering.
The capacity of single-mode fiber links with direct-modulation/direct-detection is limited by the fiber dispersion and laser chirp. which lead to frequency selective fading at the receiver. In such transmission channels, the capacity can be improved by adaptively modulated optical OFDM. In this paper, we discuss the capacity limits of such links using adaptively modulated optical OFDM both in theory...
Recently, a scheme called Orthogonal Frequency Division Multiplexing (OFDM) with Generalized Index Modulation (OFDM-GIM) is proposed, in which the number of active subcarriers in an OFDM sub-block is adjustable and a higher spectral efficiency is achieved compared with the conventional Orthogonal Frequency Division Multiplexing with Index Modulation(OFDM-IM) scheme. In this paper, based on the general...
A novel rateless coded Vector Orthogonal Frequency Division Multiplexing (V-OFDM) system for adaptive transmission over wireless channels is studied in this paper. In particular, an iterative receiver with joint V-OFDM equalization and ratelss decoding is designed, which exchanges the logarithmic likelihood information between the belief propagation decoder and the maximum likelihood equalizer or...
We have recently demonstrated the improved phase noise tolerance in coherent optical OFDM by digital coherent superposition of optical OFDM subcarriers, which are phase-conjugated pairs with Hermitan symmetry. In this approach, we realized DCS of OFDM subcarriers in single polarization (or channel), denoted as SP-DCS-OFDM. In this paper, we show that another approach is in dual polarizations, or DP-DCS-OFDM...
Digital coherent superposition (DCS) provides an interesting approach to combat the fiber nonlinearity by trading off the spectrum efficiency. In this paper, we apply DCS of phase-conjugated OFDM subcarriers in two approaches. One is the DCS of OFDM subcarriers in the single polarization, denoted as SP-DCS-OFDM. The other is in the dual polarizations, or DP-DCS-OFDM. We show that both of them can...
We experimentally demonstrate that the digital coherent superposition of optical OFDM subcarrier pairs with Hermitian symmetry can mitigate phase noise, including laser phase noise and self-phase modulation in a nonlinear optical fiber transmission.
We propose a polarization demultiplexing method in Stokes space for coherent optical PDM-OFDM without inserting training symbols. The experimental demonstration of fiber transmissions shows good performance, comparable with that of using training symbols.
In this paper, we conduct a simulation for WDM-PON with coherent optical OFDM using partial carrier filling (PCF) configuration. The impact of PCF patterns and PCF factor on transmission performance at 40-Gb/s over 100 km are studied and simulated. The influence of power into fiber is examined to obtain the optimal value corresponding to the expected transmission distance.
The introduction of OFDM into PON networks is to leverage the merits of OFDM to provide the flexibility and reduce the cost. In this paper, we present our latest works on OFDM-PON. Firstly, we propose and demonstrate a novel OFDM-PON upstream transmission architecture with traffic aggregation by orthogonal band multiplexing. The multiplexed 10-Gb/s OFDM signal is collectively received. We also conduct...
Cognitive Radio decision engine is a key technology in cognitive communication system. It can optimize transmission parameters according to the environment, and obtain the desired communication performance through multi-objective optimization algorithm. In this paper, we analyze the Cognitive Radio decision engine based on OFDM system, and introduce a binary quantum-behaved particle swarm optimization...
The timing and optical laser phase of individual bands in multi-band OFDM are correlated. We significantly reduce the OFDM overhead through using FFT window synchronization for channel estimation and sharing pilot subcarriers for phase estimation.
The channel estimation result of non-pilot subcarriers mainly depends on adjacent pilot subcarriers. A linear interpolation algorithm has been applied to the channel estimation of non-pilot subcarriers. The performance of interpolation algorithm has been simulated in a 10Gb/s direct-detection optical orthgonal frequency division multiplexing(DDO-OFDM) communication system. Constellation convergence...
Power amplifiers (PAs) are inherently nonlinear devices and are used in all transmitters of a communications equipment. To improve the performance of telecommunication channels, digital baseband predistortion is employed to compensate for PA nonlinearities. But most existing architectures base on the memoryless PA model. For wideband signal transmission, PA memory effects can no longer be ignored...
With growing demand for large data rate and high reliability wireless communication services, such as multimedia services, link adaptation techniques have emerged as powerful tools for their significant transmission data rate increase, reliability enhancement and spectrum efficiency improvement. In this paper, firstly the redundancy of a unified frame structure has been analyzed and an adaptive frame...
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