Abstract
An orthogonal frequency division multiplexing (OFDM) interconnected transmission system employing joint modulation of variable-order constellation compression and probabilistic shaping is proposed in this paper. In the proposed system, constant composition distribution matcher (CCDM) is utilized to implement probabilistic shaping, and fixed symbol-level label method is adopted to achieve the constellation compression. The coded modulation schemes can be adjusted dynamically according to the diversified traffic requirement of the users, in a bid to enhance the network utilization and provide effective end-to-end services. So far, to the best of our knowledge, it is the first time that probabilistic shaping and constellation compression modulation have been simultaneously applied to an interconnection system to achieve real-time self-tuning of transmission performances. Moreover, experimental verifications are successfully carried out by setting up a 25 km intensity-modulation/direct-detection interconnection transmission system. The results show lower bit error rate with flexible coding capability, indicating a high-potential transmission solution for the future optical communication.
Highlights
The exponential growth of global user data traffic has given tremendous momentum to the new network demands, especially for interconnected transmissions between clusters of data centers
EXPERIMENTAL RESULTS AND ANALYSIS The orthogonal frequency division multiplexing (OFDM) interconnected transmission system was utilized for experimental transmission under different constant composition distribution matcher (CCDM) probabilistic shaping signals
The constellation diagrams clearly indicate that the larger the probability distribution parameter, the smaller the number of constellation points in the outer circle of the constellation, and the more the probability distribution of constellation points is concentrated in the center of the constellation
Summary
The exponential growth of global user data traffic has given tremendous momentum to the new network demands, especially for interconnected transmissions between clusters of data centers. The intensity-modulation/direct-detection (IM/DD) passive optical network system is an effective and mature solution suitable for data center interconnection, which is simple and easy to implement [1], [2]. In addition to the new requirements for transmission rate and capacity, the data center interconnection transmission systems have higher requirements on the flexibility of receiving end. When the Baud rate is constant, the probabilistic shaping technology can bring about flexible multi-rate at the receiver owing to the fact that transmission rate varies with the information entropy. The Alcatel-Lucent Bell Labs experimentally proved that the transmission system employing probabilistic shaping has unprecedented flexibility in terms of transmission rate without increasing the system cost and implementation complexity [3]
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