Antonio Maria Cipriano

Overview of ARQ and HARQ in beyond 3G systems

In this paper, we present a review of automatic repeat request (ARQ) and hybrid ARQ (HARQ) mechanisms implemented or proposed in beyond 3rd generation (B3G) wireless systems based on OFDMA. In particular, we will focus on part of the IEEE 802.16 standard family (IEEE 802.16–2005, IEEE 802.16m) and on 3GPP Long Term Evolution (LTE). In the second part of this overview, some performance curves show how HARQ can help in reducing performance degradation in mobility context.

Calibration Issues of PHY Layer Abstractions for Wireless Broadband Systems

Today link-to-system (L2S) interfaces are more and more used in order to speed up complete system-level simulations. In this paper a simple extension to generic incremental redundancy (IR) hybrid automatic repeat request (HARQ) strategies is presented for two well-known L2S interfaces: the exponential effective SNR metric (EESM) and the mutual information effective SNR metric (MIESM). Then we focus on the problem of the L2S interface tuning, which is necessary to achieve the highest accuracy of the prediction models. The standard calibration procedure is compared with a new method, based on the average (over channel and noise) physical (PHY) layer performance. The latter, called average calibration procedure, is less time consuming than the standard procedure. Moreover, we show by simulation that the optimal calibration factors, calculated with the two methods, converge to close values thus obtaining equivalent prediction accuracy for the same L2S interface.

Minimal PAM decompositions of CPM signals with separable phase

This letter proposes a new pulse amplitude modulation decomposition of continuous phase modulation (CPM) signals under the constraint of phase response separability. The separability condition is met by a broad class of CPM signals, including full-response signals. We show that the proposed decomposition has minimal cardinality of N/sub c/=L(M-1), where M is the alphabet size and L is the CPM memory length. The cardinality increases linearly with L, while previous proposed decompositions have cardinalities M/sup L/-M/sup L-1/, which grow exponentially with L.

Evolved user equipment for collaborative wireless backhauling in next generation cellular networks

In this paper, we propose a novel architecture for next generation cellular networks that enables collaborative forwarding at Layer 2 among adjacent eNBs with the aid of enhanced user equipment (UE) devices, that act voluntarily as packet forwarders. Therefore, legacy UEs are leveraged as active network elements being capable of operating simultaneously over multiple base stations (eNBs). To this end, we introduce an evolved-UE (eUE) in order to enable reliable multi-hop operation through relaying and to achieve low-latency communication through efficient L2/MAC forwarding. Through extensive experimentation with OpenAirInterface emulation platform, we evaluated the performance and also validated the feasibility of the proposed architecture. Our results show that, in certain use cases corresponding to public safety and moving/small cell scenarios, the proposed architecture achieves significant reduction in latency (up to 16.94%) and improvement on packet loss rate (up to 59.25%), as the number of the employed eUEs increases with increasing BLER up to 20%. Moreover, the proposed architecture enables eUEs to increase the aggregated data rate in downlink by exploiting data connection to multiple eNBs at the expense of extra power consumption, which calls for the appropriate incentives to enable such a cooperation.

Maximum Likelihood Frequency Offset Estimation in Multiple Access Time-Hopping UWB

Frequency offset estimation for time-hopping (TH) ultra-wide-band (UWB) is addressed in the literature by relying on an AWGN assumption and by exploiting a periodic preamble appended to each packet. In this paper we generalize these techniques with two aims. First, we identify a solution which does not rely on any periodic structure, but can be implemented with a generic TH format. Second, we identify a solution which is robust to multiple access interference (MAI) by assuming a Gaussian mixture (GM) model for MAI. In fact, GMs have recently been identified as good descriptors of UWB interference, and they provide closed form and limited complexity results. With these ideas in mind, we build a data aided maximum likelihood (ML) estimator. The proposed ML solution shows quasi optimum performance in the Cramer-Rao bound sense, and proves to be robust in meaningful multiple user scenarios.

Parameters Selection for Filter Bank Precoded Filter Bank Multicarrier Systems

Filter Bank MultiCarrier - Offset QAM (FBMC-OQAM) is now a recognized alternative to Orthogonal Frequency Division Multiplexing (OFDM) for the transmission of multicarrier signals thanks to its improved spectral occupation. However FBMC-OQAM presents a high occurrence of power peaks. In order to reduce the occurrence of large power peaks, we present two efficient precoding methods: Filter Bank (FB) precoding and FB precoding with excess band. We propose the best choice of parameters for these methods in order to optimize performances in terms of peak power reduction, excess band, latency and overhead.

Public Protection and Disaster Relief Communication System Integrity: A Radio-Flexibility and Identity-Based Cryptography Approach

This article describes the application of radio flexibility for designing public protection and disaster relief (PPDR) wireless networks (NETs) in support of PPDR special needs, primary among which is information- transport resilience. It focuses further on the central role of mobile ad hoc NETs as the ground-segment element of the total architecture since the eventual solution must support rapid, robust, secure, scalable, and connectivityoriented communications. Research challenges associated with the provision of the necessary diversity at all communication layers as a means to such robustness are identified. Security aspects are addressed through a signature scheme based on identity key cryptography. Finally, a use case based on flexible multihop mobile ad hoc network (MANET) path establishment for harsh environments is presented.

Performance of UWB Impulse Radio in strong MAI with frequency offsets estimation

This paper investigates the performance of a coherent receiver for ultra-wide-band Impulse Radio. Specifically, we suppose that the useful signal is affected by a dispersive channel and that the receiver collects also multiple access interference (MAI), while experiencing frequency drifts due to clock mis-alignments. Building upon a Gaussian mixture (GM) model for MAI, the receiver uses a space alternating generalized expectation maximization (SAGE) estimation approach for all unknowns quantities: channel, frequency offsets, and data. Iterative and adaptive algorithms are formulated. The latter enables a low-complexity implementation of the whole estimation procedure with small performance loss. The provided simulations are a first step in evaluating the performance of a receiver coping with all the most critical uncertainties at the same time.

Scenarios for 5G networks: The COHERENT approach

Efficient coordination among network elements and optimal resource utilization in heterogeneous mobile networks (HMNs) is a key factor for the success of future 5G systems. The COHERENT project focuses on developing an innovative programmable control and coordination framework which is aware of the underlying network topology, radio environment and traffic conditions, and can efficiently coordinate available spectrum resources. In this paper, we provide a set of scenarios and use cases that the COHERENT project intends to address.

Design and evaluation of cooperative broadcast in a wireless mesh network based on 3GPP LTE

This paper presents results of the Seventh Framework Programme (FP7) LOLA (achieving LOw LAtency in wireless communications) project about the design of a cooperative broadcast (CB) technique based on a decode and forward (DF) protocol, in the context of a clusterized wireless mesh network (WMN) based on 3GPP LTE PHY/MAC layers. The CB technique is compared to a baseline broadcast technique, obtained by packet propagation over a predetermined tree combined with local broadcasts inside the clusters. The novelty of the paper consists in presenting a design of CB which takes into consideration a number of practical issues set by the 3GPP LTE framework, like subframe design or MAC signalling. Moreover, simulation results are presented comparing the two techniques and presenting their advantages and drawbacks.