Spectrally Efficient Optical Systems and Congestion Aware Routing
2 journal papers by EEE academics in IEEE Photonics Technology Letters have been rated the most popular articles in February and April 2014. Firstly, in February a journal paper on spectrally efficient optical systems from Professor Izzat Darwazeh's Communication and Information Systems Group was the most downloaded paper according to usage statistics. The paper proposes and demonstrates a new optical spectrally efficient frequency division multiplexing (O-SEFDM) system, where non-orthogonal and overlapping sub-carriers are employed to provide higher spectral efficiency relative to optical-orthogonal frequency division multiplexing (O-OFDM). The O-SEFDM technique can increase spectral efficiency in both the electrical and optical domains. It is experimentally shown that for bandwidth saving up to 25%, we can achieve the same performance as O-OFDM. This is the first experimental verification of 25% optical faster than the Nyquist rate. Furthermore, for approximately the same spectral efficiency, 4QAM O-SEFDM outperforms standard 8QAM by 1.6 dB. It is experimentally shown that a lower-order modulation format can achieve a better performance by replacing a higher one.
To read or download the paper which has now been in the top 25 most popular papers for the last 4 months, visit: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6678620
Secondly, in April, Dr Seb Savory’s paper titled ‘Congestion Aware Routing in Nonlinear Elastic Optical Networks’ became the most downloaded paper. His paper proposes to use congestion aware routing in a nonlinear elastic optical network and demonstrate its efficacy for the NSFNET reference network (14 nodes, 22 links). The network is sequentially loaded with 100 GbE demands until a demand becomes blocked, this procedure being repeated 10000 times to estimate the network blocking probability (NBP). Three routing algorithms are considered: 1) shortest path routing; 2) simple congestion aware algorithm; and 3) weighted congestion aware routing algorithm with 50, 25, 12.5, and 6.25 GHz resolution flexgrids. For NBP = 1% using a 50 GHz grid, congestion aware routing doubles the network capacity compared with the shortest path routing. When congestion aware routing is combined with a 6.25 GHz resolution flexgrid, a fivefold increase in network capacity is afforded.