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It has been shown that due to its smaller signal bandwidth (96 KHz), DRM+ signal could suffer from flat fading degradation at low receiver speeds, particularly in urban environments. To alleviate this problem, a simple transmit delay diversity (TDD) has been proposed in the standard. This paper tries to investigate this issue by presenting the performance results of multipath fading characterizations...
This work considers the scheduling problem for the packets with strict maximum tolerable delay (deadline) constraint. We discuss a multiuser scheduling scheme which schedules the users based on their instantaneous channel conditions, packet deadline and backlog of the buffered packets. The scheme is analyzed in large system limit for the single and multicell cases. The aim is to minimize the system...
Adaptive modulation and coding (AMC) and opportunistic scheduling are widely used in modern broadband wireless communication systems to adapt to time-dependent user-dependent channel fading. On one hand, AMC and opportunistic scheduling can adapt to channel variations and take advantage of multiuser diversity to effectively improve throughput. On the other hand, due to the user-dependent wireless...
In this work, we propose an instantaneous rate based cooperative medium access control (MAC) protocol (termed as IrcMAC) and compare its performance gain over the existing cooperative MAC protocols under heavy load and fast fading conditions. CoopMAC I protocol, proposed in [5] which selects either direct path or relay path based on rate comparison to enhance average throughput and delay, performs...
Wireless networks are characterized by a dynamic topology triggered by the nodes mobility. Thus, the wireless multi-hops connection and the channel do not have a determinist behaviour such as: interference or multiple paths. Moreover, the nodes' invisibility makes the wireless channel difficult to detect. This wireless networks' behaviour should be scrutinized. In our study, we mainly focus on radio...
This paper presents a low-power MMSE MIMO detector using a dynamic voltage wordlength scaling (DVWS) technique for 4×4 MIMO-OFDM systems. A MIMO MMSE detector requests high performance computing for real-time processing. A pipelined MMSE detector using Strassen's algorithm has been developed in our previous work. However, it consumes significant power and thus, we have to consider a low-power solution...
In this paper, we obtain the capacity region for the AWGN Multiple Access Channel (MAC) with transmitters equipped with energy harvesters. We next obtain the sum-of-rates capacity for the flat fading Multiple Access Channel with energy harvesting transmitters. We then develop low delay, adaptive transmission strategies that surprisingly achieve near optimal performance under finite battery resource...
Intra-vehicular wireless sensor networks is a promising new research area that can provide part cost, assembly, maintenance savings and fuel efficiency through the elimination of the wires, and enable new sensor technologies to be integrated into vehicles, which would otherwise be impossible using wired means, such as Intelligent Tire. The most suitable technology that can meet high reliability, strict...
We consider in this paper downlink scheduling at the Medium Access Layer (MAC) layer for delay sensitive traffic in wireless systems based on Orthogonal Frequency Division Multiple Access (OFDMA). We refer in particular to next generation wireless systems such as 3GPP-LTE. We propose an Opportunistic Packet Loss Fair (OPLF) scheduling algorithm based on calculating a simple dynamic priority function...
Measuring and predicting users quality of experience (QoE) in dynamic network conditions is a challenging task. This paper presents results related to a decision-theoretic methodology incorporating Bayesian networks (BNs) and utility theory for quality of experience (QoE) measurement and prediction in mobile computing scenarios. In particular, we show how both generative and discriminative BNs can...
An extended analog joint source-channel coding (JSCC) multiple description (MD) scheme is introduced. This new scheme extends a previously presented analog JSCC-MD scheme in order to work at different bandwidth ratios. This scheme is suitable for transmissions through parallel AWGN on-off channels and parallel slow-fading channels. The strengths of the proposed scheme in comparison with other coding...
Although most of the conventional localization algorithms rely on Line of Sight (LOS) conditions, fingerprinting allows positioning in multipath and even in Non-LOS (NLOS) environments. In contrast to the traditional Received Signal Strength (RSS), the Power Delay Profile (PDP) fingerprint may allow positioning on the basis of a single link if the multipath is rich enough. Fingerprinting is a pattern...
An overview of the unique challenges in underwater acoustic (UWA) communication in ocean environment is presented. The UWA channel is compared with conventional RF channels. Several design considerations applicable to the physical layer design of a UWA communication system is described based on field measurements. The unique problems in synchronization under high Doppler are described highlighting...
In this paper we consider a single discrete time queue with infinite buffer. The channel may experience fading. The transmission rate is a linear function of power used for transmission. In this scenario we explicitly obtain power control policies which minimize mean power and/or mean delay. There may also be peak power constraint.
The conflict between energy consumption and battery capacity has become more significant in modern mobile terminals that support various functions in addition to traditional voice. It is of great importance to extend battery lifespan and at the same time to guarantee the required quality of service (QoS). In this paper, we investigate the relationship between the battery lifespan of a mobile terminal...
Cooperative schemes for critical content distribution over vehicular networks are presented and analyzed. The first scheme is based on unicasting from the base station, whereas the second is based on threshold based multicasting. Long Term Evolution (LTE) is used for long range communications with the base station (BS) and 802.11p is considered for inter-vehicle collaboration on the short range. A...
There are many studies dealt with handoff management in mobile communication systems and some of these studies presented handoff schemes to manage this important process in cellular network. All previous schemes used relative signal strength (RSS) measurements. In this work, a new proposed handoff scheme had been presented depending not only on the RSS measurements but also used the threshold distance...
This paper shows a detailed performance evaluation of the bandwidth allocation algorithm presented in [1] by the same research group and briefly reminded here. Telecommunications networks are composed of functional layers acting in cascade. The mentioned algorithm adapts the bandwidth to be allocated to a buffer which conveys heterogeneous traffic in a layer-in-cascade functional model, is based only...
In this paper, the performance of adaptive modulation for multiuser amplify-and-forward relay networks over Nakagami-$m$ fading is studied. Specifically, adaptive discrete rate five-mode $M$-ary quadrature amplitude modulation is employed with fixed switching thresholds. In particular, the detrimental effect of feedback delays in multiuser scheduling is quantified. To this end, an upper bound of the...
To better exploit the spectrum resources a wireless sensor network can be used to assists a secondary cognitive radio network by providing information about the current primary spectrum occupancy. In this paper we study the performance of the secondary network when it is co-located with and having similar cell size as a mobile primary network that uses a cellular reuse pattern with seven frequencies...
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