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How good is the performance of the existing Inter-Cell Interference Coordination (ICIC) schemes when dealing with users moving at high speeds? In this paper, we evaluate a number of existing schemes under high user mobility conditions. Then, we propose a dynamic decentralized ICIC scheme that requires no apriori frequency planning. The proposed scheme minimizes the amount of data needs to be exchanged...
Imperfect channel estimation can have a severe impact on the performance of coherent detection systems. In this paper we study the effect of imperfect channel knowledge in the performance of SC-FDE (Single Carrier with Frequency Domain Equalization). We propose a low complexity linear FDE which incorporates knowledge of the channel estimation error variance and derive analytical BER expressions. It...
In wireless sensor networks (WSNs), real-time service is one of the important issues. Typically, existing studies for the service are relied on beacons. Recently, beaconless routing has been proposed to overcome control overhead for resource constrained environment of WSNs. Thus, real-time communication based on the beaconless scheme could give great advantages with less energy consumption. To do...
This paper presents a digital baseband IC design based on OFDM PHY for a 60GHz proximity communication system. We propose a low computational complexity OFDM demodulator with a carrier frequency offset estimation method in polar coordinates suitable for high-speed parallel architecture. The proposed architecture is implemented in 65nm CMOS technology, and is experimentally verified to achieve the...
Due to the individualistic nature of the femtocells and the uncertainty on the number and location of these devices, self-organization techniques play a very important role in successfully deploying and managing a large femtocell tier. This paper proposes a distributed power self-optimization scheme to suppress the interference and optimize the energy efficiency. First, the non-cooperative power self-...
In this paper, we investigate the channel regularization and vector perturbation techniques at the source and linear precoding at the relay to enhance the performance of a dual- hop amplify and-forward (AF) relay downlink system. At first, an optimal regularized channel inversion scheme via regularization parameter is proposed. The joint channel regularization and linear precoder design at the relay...
This paper presents a novel time-domain parameter (TDP) extraction scheme for channel estimation and feedback in the LTE-advanced systems. The TDP extraction improves the channel estimation accuracy by an order of magnitude over the interpolation-based methods, has extremely low complexity com-pared to MMSE approaches, and is very close to or even outper-forms the Bayesian MMSE lower bound. The mobile...
In this paper, we introduce a caching proxy architecture, which is used to (i) enable seamless device switching in the increasingly connected mobile user space, (ii) create user-based application optimizations, and (iii) realize energy savings in application contexts. We provide an overview of the static long-term gains that can be expected for individual applications using a generic cost approach...
Content Centric Networking (CCN) has been recently proposed as a potential candidate for the future Internet architecture. It allows users to focus on the data they are interested in, rather than having to connect to a specific physical host where the data locates. CCN is claimed to inherently support mobility. While this is true for content receivers, source mobility as well as handovers still remain...
It is well known that the performance of the energy detector necessitates a prior knowledge about noise variance and gravely degraded for low SNR. In this paper, we proposed a novel combined second order moment, CSOM, based multiple antenna sensing. Its performance does not depend asymptotically on the noise variance. Simulations show decision accuracy improvement compared to the classical square...
In last years, wireless networking is becoming very popular because it is able to satisfy user requests in terms of Quality of Service (QoS); when mobility is present, perhaps, hand-over issues are relevant when hosts change coverage areas during their active sessions. It is very important to mitigate mobility effects, employing an appropriate bandwidth management policy. In our work, we propose two...
This paper investigates the performance of energy detection (ED) for random signals having sufficient autocorrelation. As opposed to the uncorrelated noise, practical communication signals have autocorrelation, which can be exploited for optimal detection if the correlation is known a priori. Otherwise ED can be employed as a generalized sensing method for unknown signals. However, since ED is optimal...
In order to get practical experience with heterogeneous LTE networks Deutsche Telekom and Huawei built up a field trial network consisting of one macro site and eight pico sites which are spatially spread in different environments to cover many pico site deployment scenarios. The main performance results obtained in the field trial are presented for both relevant deployment aspects: Either macro and...
Voice over LTE (VoLTE) is crucial for mobile network operators in order to avoid falling back to 3G or 2G for voice services. Since VoLTE uses IP as transport protocol, RObust Header Compression (ROHC) is a mandatory feature to reduce header overhead and transport efficiency. ROHC defines two different bidirectional modes -- (R)eliable and (O)ptimistic -- with significant differences in implementation...
The introduction of Machine-to-Machine (M2M) communications in cellular networks creates a whole new set of challenges due to the unique service requirements and features of M2M devices. One such challenge is the radio resource management, particularly on the uplink. The requirements of high energy efficiency coupled with diverse QoS requirements of M2M devices and conventional Human-to-Human (H2H)...
In this paper, the use of network coding is exploited to improve the cooperative diversity order of multi-source multi-hop networks with line topology. We elaborate on a previous system model by allowing user nodes to be arbitrarily located along the line network, to have the ability to perform network decoding, and to be able to listen to upstream nodes. The recently introduced generalized dynamic-network...
We consider a cooperative cognitive radio network with one primary user and many secondary users. In each transmission frame, one secondary user is selected to act as a relay for the primary user and also transmits its own data. Three different schemes for the secondary user's transmission is studied, namely, time-splitting, superposition coding, and a combined scheme that takes advantages of both...
In Delay Tolerant Networks (DTN), contemporaneous end-to-end paths are rarely available. Routing in such networks is therefore one of the challenging issues. When the DTN is made of humans, human mobility characterizes the forwarding opportunities. To leverage the diversity of the strengths of social ties, a number of utility-based routing policies have been proposed. In this paper we first address...
A very large MIMO system has a potential to achieve extremely-high system throughput. In general, however, algorithms detecting spatially-multiplexed signals require the complexity proportional to the cubed number of antenna elements in the least case. Thus, the implementation of an antenna array with an order of 100 elements becomes very difficult. In this paper, we focus on the algorithm which is...
Survivability is crucial in Wireless Sensor Networks (WSNs) especially when they are used for monitoring and tracking applications with limited available resources. In this paper we are proposing the use of an energy Efficient Cognitive Unicast Routing (ECUR) protocol that tries to keep a balance between the energy consumption and the packet delay in a WSN. The proposed routing protocol has a next...
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