Konstantinos Ntougias

Learn More
Exploiting additional radio spectrum is key to respond to the unprecedented capacity demands of mobile broadband communication systems in recent years. In fact, most of the frequency bands suitable for mobile communications are already in use by other radio services, and spectrum refarming is usually not possible or constitutes a highly time-consuming(More)
Recently, several advanced multi-antenna radio communications technologies have emerged to meet the increased capacity demands in wireless multiuser networks. Despite their great potential, the extent of these techniques' practical applicability still remains questionable, since they have to face either backhaul limitations or cost and hardware constraints.(More)
In order to meet the exponentially growing capacity demands of future mobile radio communication systems, the synergy of spectrum sharing methods, multi-antenna transmission schemes, small-cell offloading, and cooperative communication techniques is suggested. In this context, the mitigation of harmful interference, the provision of quality of service (QoS)(More)
In this work, we present a method that enables the application of robust, low-complexity, arbitrary channel-aware precoding at single-fed load-controlled parasitic antenna arrays. Moreover, we describe the extension of this technique to multi-cell setups. Finally, we evaluate the sum-rate throughput performance of several multi-cell precoding schemes(More)
Least recently used (LRU) is the most commonly applied strategy to update the content of caches in computing and database systems as well as for Web caching. Although some case studies have shown that LRU hit rates can be low when compared to Web caching strategies being aware of complete statistics of past requests, proposed alternatives seem too complex(More)
Responding to the IEEE DySPAN 2015 5G Spectrum Sharing Challenge, in this paper we propose a SU system that is equipped with a parasitic antenna array and incorporates a low-rate feedback technique in order to accomplish highly efficient spectrum sharing. This approach optimizes the performance of both the PU and SU systems, in terms of the achieved(More)
Single-user multiple-input / multiple-output (SU-MIMO) communication systems have been successfully used over the years and have provided a significant increase on a wireless link's capacity by enabling the transmission of multiple data streams. Assuming channel knowledge at the transmitter, the maximization of the mutual information of a MIMO link is(More)