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We implemented a flexible transmission system operating at adjustable data rate and fixed bandwidth, baudrate, constellation and overhead using probabilistic shaping. We demonstrated in a transmission experiment up to 15% capacity and 43% reach increase versus 200 Gbit/s 16-QAM.
In wireless local area networks, spatially varying channel conditions result in a severe performance discrepancy between different nodes in the uplink, depending on their position. Both throughput and energy expense are affected. Cooperative protocols were proposed to mitigate these discrepancies. However, additional network state information (NSI) from other nodes is needed to enable cooperation...
In the first chapter of Shannon's A Mathematical Theory of Communication, it is shown that the maximum entropy rate of an input process of a constrained system is limited by the combinatorial capacity of the system. Shannon considers systems where the constraints define regular languages and uses results from matrix theory in his derivations. In this work, the regularity constraint is dropped. Using...
As a theoretical concept, and a means to understand the potential of interference alignment, in this paper we investigate possibilities to place n transmitter-receiver pairs in n - 1 dimensions such that the interference from unintended transmissions is aligned at each receiving node. By such an arrangement each link has half of the capacity available, at least in theory. Regular patterns of stations...
This paper addresses the problem of resource allocation for orthogonal frequency division multiple access (OFDMA) downlink that aims at minimizing the total transmission power under data transmission constraints. To accelerate this multiuser resource allocation with small performance loss, an efficient technique is introduced that provides the power variation of single-user water-filling when the...
Using the concept of discrete noiseless channels, it was shown by Shannon in A Mathematical Theory of Communication that the ultimate performance of an encoder for a constrained system is limited by the combinatorial capacity of the system if the constraints define a regular language. In the present work, it is shown that this is not an inherent property of regularity but holds in general. To show...
The frequency selectivity of wireless communication channels can be characterized by the delay spread Ds of the channel impulse response. If the delay spread is small compared to the bandwidth W of the input signal, that is, DsW ?? 1, the channel appears to be flat fading. For DsW ?? 1, the channel appears to be frequency selective, which is usually the case for wideband signals. In the first case,...
Cooperative communications have emerged as a significant concept to improve reliability and throughput in wireless systems. On the other hand, WLANs based on random access mechanism have become popular due to ease of deployment and low cost. Since cooperation introduces extra transmissions among the cooperating nodes and therefore increases the number of packet collisions, it is not clear whether...
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