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For dense small cell deployment in centralized baseband architecture, wireless fronthaul is a cost efficient and flexible alternative to fiber-based fronthaul links. Due to the available wide bandwidth, millimeter-wave technology is the most promising choice to realize multi-gigabit wireless transmission of the common public radio interface (CPRI). In this paper, we present a novel differential encoding...
The use of centralized signal processing for dense urban mobile networks is gaining interest both in research and in industry. Gathering most of the base station functionalities in a processing pool would enable capacity sharing and the implementation of advanced techniques such as coordinated multi-point. Nevertheless, this puts stringent requirements on the network interconnecting the processing...
Transport of mobile fronthaul traffic has a tight latency requirement of about 250us one-way. The best solutions today are based on expensive point-to-point (PtP) fiber links and PtP wavelength division multiplexing. A time division multiplexed passive optical network (TDM-PON) is less expensive, but has a poor latency of about 1ms. Guidelines are suggested to design an optimized TDM-PON with minimal...
This paper proposes a new analytical model for the performance of a p persistent slotted Aloha medium access protocol in a Cognitive Radio Network (CRN) composed by a single Primary user (PU) and several Secondary users (SUs) with Poisson traffic. SUs run a synchronized sensing-access operation cycle, and when they have a packet to transmit and the channel is sensed free, they access to the data slots...
In this paper, we investigate the outage performance of an amplify-and-forward (AF) multiple input multiple output (MIMO) opportunistic relay selection system under time-varying channels. A practical scenario is considered, where both the relay selection and the beamforming transmission are performed with outdated channel state information (CSI), due to channel fluctuations and delays involved in...
Device-to-device (D2D) communication, where user equipments (UEs) in proximity communicate directly with each other, is an alternative technology for densification in future wireless communications featuring extremely dense and heterogeneous networks. The intrinsic characteristics of D2D communication include (1) limited energy capacity of battery powered UEs, (2) necessary power consumption to maintain...
Network-facilitated device to device (D2D) communication is expected to play a central role in 5th generation cellular systems, as this allows to substantially reduce the end-to-end latency in mission-critical communication use cases, but also to obtain network and spectral efficiency improvements through the exploitation of proximity gains, hop gains and reuse gains in mobile broadband scenarios...
High resolution radio based positioning and tracking is a key enabler for new or improved cellular services. In this work, we are aiming to track user movements with accuracy down to centimeters using standard cellular bandwidths of 20–40 MHz. The goal is achieved by using phase information from the multi-path components (MPCs) of the radio channels. First, an extended Kalman filter (EKF) is used...
Ultra-wide bandwidth (UWB) systems allow for accurate localization to tackle and complement the GPS-aided solutions, which are impractical in weak signal environments. We consider the problem of fast link scheduling in the medium access control (MAC) layer for UWB localization. We present an optimization strategy to perform robust ranging scheduling with localization constraints. Given the complexity...
We consider Bayesian ranging methods for localization in wireless communication systems. Based on a channel model and given priors for the range and the line-of-sight (LOS) condition, we propose range estimators with and without LOS detection. Since the pdf of the received frequency-domain signals is unknown, we approximate the maximum-a-posteriori (MAP) and the minimum mean-squared error (MMSE) estimators...
Multipath-assisted localization is a promising concept for cooperative agent networks to guarantee robust and accurate positioning in indoor environments with harsh radio channel characteristics. It uses two types of measurements: (i) bistatic measurements between agents and (ii) monostatic (bat-like) measurements by the individual agents. This paper presents an in-depth analysis of the position-related...
In this paper, we study Two-Way Relaying (TWR) networks well-known for its throughput merits. In particular, we study the fundamental throughput delay trade-off in TWR networks using opportunistic network coding (ONC). We characterize the optimal ONC policy that maximizes the aggregate network throughput subject to an average packet delay constraint. Towards this objective, first, we consider a pair...
Wideband high-dimensional antenna arrays are expected to play a key role in future 5G wireless systems. Due to narrow beamwidths, phased array/beamforming methods are the natural choice for design and analysis of high-dimensional MIMO systems. However, conventional methods are based on the narrowband assumption which is violated as the bandwidth and array dimension increase. In this paper we revisit...
The fifth generation (5G) of cellular networks is starting to be defined to meet the wireless connectivity demands for 2020 and beyond. One area that is considered increasingly important is the capability to provide ultra-reliable and low-latency communication, to enable e.g., new mission-critical machine-type communication use cases. One such example with extremely demanding requirements is the industrial...
This paper presents 28 GHz and 73 GHz millimeter-wave propagation measurements performed in a typical office environment using a 400 Megachip-per-second broadband sliding correlator channel sounder and highly directional steerable 15 dBi (30° beamwidth) and 20 dBi (15° beamwidth) horn antennas. Power delay profiles were acquired for 48 transmitter-receiver location combinations over distances ranging...
This work focuses on scheduling multiple video flows on the downlink of a wireless system based on Orthogonal Frequency Division Multiple Access (OFDMA), such as the LTE/LTE-A standard. We propose a joint multi-user scheduling and multi-user rate adaptation strategy by considering Scalable Video Coding (SVC) which facilitates the truncation of bit streams, thus allowing graceful degradation of video...
The capacity limits of the Random Access Channel (RACH) of Long Term Evolution (LTE) for highly dense Machine-to-Machine communications are studied in this paper. We consider the case study when a high number of devices attempt to transmit information to the same base station in a very short period of time. Simulations have been performed considering several parameter configurations related to the...
Machine to machine (M2M) communications is one of the key underpinning technologies for Internet of Things (IoT) applications in 5G networks. The large scale of M2M devices imposes challenge on conventional medium access control protocols. In this paper, we propose a reinforcement learning (RL) based duty cycle control for dominant short-range technology IEEE 802.15.4 to provide high performance and...
We propose a sticky transfer framework to enhance successful message transfers in a Delay- and Disruption-Tolerant Network (DTN). We propose a sticky transfer protocol within the framework that enables mobiles nodes to “stick” to each other for a longer period of time in order to complete the transmissions of the messages needed to be sent. A mobile node A makes the decision of whether to stick to...
With the development of mobile internet, wireless communications via mobile devices in the form of Delay Tolerant Networks (DTNs), becomes a hot research topic. One critical issue in the DTNs with social characteristics is that there could exist selfish nodes which are unwilling to forward messages from strangers and malicious nodes which intentionally impair normal communication. Although there are...
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