Konstantinos Nikitopoulos

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The increasing need for multimodal terminals that adjust their configuration on the fly in order to meet the required quality of service (QoS), under various channel/system scenarios, creates the need for flexible architectures that are capable of performing such actions. The paper focuses on the concept of flexible/reconfigurable radio systems and(More)
This paper presents the design and implementation of Geosphere, a physical- and link-layer design for access point-based MIMO wireless networks that consistently improves network throughput. To send multiple streams of data in a MIMO system, prior designs rely on a technique called zero-forcing, a way of "nulling" the interference between data streams by(More)
Iterative channel estimation and decoding result in significant performance gains but at high computational cost. In this paper, an iterative channel estimation control is proposed to reduce the complexity by only refining the channel estimates which significantly affect the decoding performance. Simulation results demonstrate that significant complexity(More)
In this paper, the iterative scheduling issue for multiple-input multiple-output (MIMO) systems with turbo codes is addressed based on the informed asynchronous scheduling, initially used for scheduling low-density parity-check (LDPC) decoding. For the iterative MIMO demapping and turbo decoding, the convergence behavior by using the informed asynchronous(More)
– In this paper two complexity efficient soft sphere-decoder modifications are proposed for computing the max-log LLR values in iterative MIMO systems, which avoid the costly, typically needed, full enumeration and sorting (FES) procedure during the tree traversal without compromising the max-log performance. It is shown that despite the resulting increase(More)