The new types of industry-driven applications that need to be supported by low-power wide-area networks (LP-WANs), such as remote control or metering of devices within the massive machine-type infrastructures (e.g., Smart Grids), require a permanent connection to the remote server. In addition, there is also a shift in the communication paradigm, as the user equipment (UE) nodes are queried in regular and frequent intervals. Notably, the presence of this type of traffic may drastically deteriorate the performance of LPWAN technologies initially developed to support conventional use-cases characterized by non-synchronized transmissions. Though none of the LPWAN technologies is inherently designed to handle such demanding communication patterns, the narrowband Internet of things (NB-IoT) still stands for the best candidate as it operates within the license frequency spectrum. To optimize the delay performance of both types of traffic coexisting at the NB-IoT air interface, we propose an approach based on spreading the message transmission time instants of regular and stochastic traffic. We show an optimal value of the spreading interval minimizing the message transmission delay of regular traffic and propose a mathematical model to estimate its value. By parameterizing the model using a detailed measurements campaign of NB-IoT, we show that the optimal value of spreading interval and associated mean message delay is a linear function of the number of UEs. We report these values for a wide range of UEs in the coverage area of the NB-IoT base station and show that conventional stochastic traffic does not influence regular traffic performance.

While optimizing the system-level performance in a network of advanced high-end wearables, millimeter-wave (mmWave) medium access protocols may benefit from leveraging the information on the spatial and temporal dynamics of the radio channel. In this paper, we aim to bridge the existing gap in mmWave on-body propagation studies by analyzing the channel structure based on an extensive shooting-and-bouncing ray simulations. Particularly, we model a set of on-body trajectories and illustrate the evolution of the core channel parameters as well as address the specifics of their dynamics, which can be exploited in subsequent protocol development. As a key contribution of this study, we propose a methodology for processing and applying the simulation data as well as illustrate our approach through an example of estimating the effects of directionality and antenna beam misalignment. Our results and data, also available online, facilitate the system-level analysis and performance evaluation of various on-body mmWave systems.

We address the problem of uncoordinated massive random-access in the Gaussian multiple access channel (MAC). The performance of low-complexity T-fold irregular repetition slotted ALOHA (IRSA) scheme is investigated and achievability bounds are derived. The main difference of this scheme in comparison to IRSA is as follows: any collisions of order up to T can be resolved with some probability of error introduced by noise. In order to optimize the parameters of the scheme we combine the density evolution method (DE) proposed by G. Liva and a finite length random coding bound for the Gaussian MAC proposed by Y. Polyanskiy. As energy efficiency is of critical importance for massive machine-type communication (mMTC), then our main goal is to minimize the energy-per-bit required to achieve the target packet loss ratio (PLR). We consider two scenarios: (a) the number of active users is fixed; (b) the number of active users is a Poisson random variable.

We introduce a new model of spatial random multiple access systems with a non-standard departure policy: all arriving messages are distributed uniformly on a finite sphere in the space, and when a successful transmission of a single message occurs, the transmitted message leaves the system together with all its neighbours within a ball of a given radius centred at the message's location. We consider three classes of protocols: centralised protocols and decentralised protocols with either ternary or binary feedback; and analyse their stability. Further, we discuss some asymptotic properties of stable protocols.

This paper1considers a class of multi-channel random access algorithms, where contending devices may send multiple copies (replicas) of their messages to the central base station. We first develop a hypothetical algorithm that delivers a lower estimate for the access delay performance within this class. Further, we propose a feasible access control algorithm achieving low access delay by sending multiple message replicas, which approaches the performance of the hypothetical algorithm. The resulting performance is readily approximated by a simple lower bound, which is derived for a large number of channels.

In this paper, we propose a simple and practical method to analyze multi-channel random-access systems with a large number of machine-to-machine (M2M) devices, which helps determine the average data access latency, as well as characterize the system stability region. The proposed methodology can be applied to random-access 3GPP LTE channels and delivers the system-optimal retransmission probability for M2M data access, which is a key parameter for highly-populated industry-grade systems with stringent data access latency requirements. The presented numerical results compare our proposed retransmission control solution against a heuristic device-centric retransmission control procedure and quantify the respective performance gains.

The emerging fifth-generation (5G) wireless technology will need to harness the massively unused millimeter-wave (mmWave) spectrum to meet the projected acceleration in mobile traffic demand. Today, the available range of mmWave-based solutions is already represented by IEEE 802.11ad (WiGig), IEEE 802.15.3c, WirelessHD, and ECMA-387 standards, with more to come in the following years. As the key performance-related aspects of these enabling technologies are rapidly taking shape, the primary research challenge shifts to characterizing network energy efficiency, among other system-level parameters. This is particularly important in scenarios that are not handled by current 4G communication networks, including congested public places, homes, and offices. In these dense deployments, wireless wearable devices are increasingly proliferating to assist in diverse user needs. However, mmWave operation in crowded environments, and especially for multiple neighboring personal networks, is not nearly well-understood. Bridging this gap, we conduct a full-fledged energy efficiency assessment of mmWave-based “high-end” wearables that employ advanced antenna beamforming techniques. Our rigorous analytical results shed light on the underlying scaling laws for the interacting mmWave-based networks based on IEEE 802.11ad and quantify the impact of beamforming quality on system energy efficiency under various conditions. Furthermore, we look at the system optimization potential subject to realistic hardware capabilities.

We consider centralized wireless networks for users of video streaming services. If the network is congested, wireless channel resources can be insufficient to satisfy all user requests. In this case QoE with some users may heavily degrade (video playback may periodically interrupt due to rebuffering effect, or startup buffering can take an intolerably long time). These negative effects can be partly reduced by appropriate scheduling of radio resources of the network. In the paper we propose a lower bound for the mean user waiting time spent on startup buffering and rebufferings in all possible schedulers. Through asymptotic analysis and simulation, this bound is compared with the results of a few generic scheduling policies. The proposed bound can be used as a basic performance test for existing and new algorithms of radio resources management in wireless video streaming networks.

In this paper, we consider a wireless cellular system with an unbounded population of machine-type users. The system provides a number of non-interfering slotted-time channels which users contend for when sending their uplink data packets. We propose a provably stable control procedure for the channel access probability in the sense that it maintains a finite number of unserviced users in the system. We also compare the proposed algorithm against the optimal multi-channel slotted Aloha to conclude that our solution demonstrates near-optimum performance.

In this paper we propose a novel efficient adaptive binary arithmetic coder which is multiplication-free and requires no look-up tables. To achieve this, we combine the probability estimation based on a virtual sliding window with the approximation of multiplication and the use of simple operations to calculate the next approximation after the encoding of each binary symbol. We show that the proposed algorithm is faster and provides a better compression efficiency compared to the M-coder in the CABAC entropy coding scheme of the H.264/AVC video coding standard.

This paper disscuses latency-constrained video transmission over high-speed wireless personal area networks. Low-power single-layer video compression is proposed as an alternative to others video processing approaches. End-to-end distortion and end-to end latency in video transmission system are analyzed. A near-optimal video source rate control based on MINMAX quality criteria is introduced. Practical results for video encoder based on H.264/AVC standard are also given.

In this paper we propose a novel model for the capacity analysis on the reservation-based random multiple access system, which can be applied to the medium access control protocol of the emerging WiMax technology. In such a wireless broadband access system, in order to support QoS, the channel time is divided into consecutive frames, where each frame consists of some consequent mini-slots for the transmission of requests, used for the bandwidth reservation, and consequent slots for the actual data packet transmission. Three main outcomes are obtained: first, the upper and lower bounds of the capacity are derived for the considered system. Second, we found through the mathematical analysis that the transmission rate of reservation-based multiple access protocol is maximized, when the ratio between the number of mini-slots and that of the slots per frame is equal to the reciprocal of the random multiple access algorithm's transmission rate. Third, in the case of WiMax networks with a large number of subscribers, our analysis takes into account both the capacity and the mean packet delay criteria and suggests to keep such a ratio constant and independent of application-level data traffic arrival rate.