Network Utility Maximization Models (NUM) have been successfully applied to address multiple resource allocation problems in communication networks. This paper explores for the first time its application to model the bandwidth allocation problem in PONs and Long-Reach PONs. Using the NUM model, we propose the FEx-DBA (Fair Excess-DBA) algorithm a new Dynamic Bandwidth Allocation (DBA) scheme to allow a fair and efficient allocation of the upstream channel capacity. The NUM framework provides the mathematical support to formally define the fairness concept in the resource allocation, and the guidelines to devise FEx-DBA. A simulation study is conducted, so that FEx-DBA is compared to a state-of-the-art proposal. We show that FEx-DBA: (i) provides bandwidth guarantees to the users according to the Service Level Agreement (SLA) contracted, and fairly distributes the excess bandwidths among them, (ii) has a stable response and fast convergence when traffic or SLAs change, avoiding the oscillations appearing in other proposals, (iii) improves average delay and jitter measures and (iv) only depends on a reduced set of parameters, which can be easily tuned.

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Radio frequency identification technology (RFID) is considered as the reference technology for wireless identification and item traceability. Supermarkets are one of those scenarios where the RFID potential can be harnessed. In theory, RFID in supermarkets shows several advantages compared with traditional barcode systems, offering real-time inventory, stock control, cash queues, among others. In practice, its massive and global implementation is still being delayed due to the high quantity of factors that degrade the RFID system performance in these scenarios, causing uncontrolled items and identification losses and, at the end, economical losses. Some works in the scientific literature studied a single or a set of problems related to RFID performance, mostly focused on a specific communication layer: antennas and hardware design, interferences at physical layer, medium access control (MAC) protocols, security issues, or middleware challenges. However, there are no works describing in depth the set of factors affecting RFID performance in a specific scenario and contemplating the entire communication layer stack. The first challenge of this chapter is to provide a complete analysis of those physical and environmental factors, hardware and software limitations, and standard and regulation restrictions that have a direct impact on the RFID system performance in supermarkets. This analysis is addressed by communication layers, paying attention to the point of view of providers, supermarket companies, and final customers. Some of the most feasible and influential research works that address individual problems are also enumerated. Finally, taking the results extracted from this study, this chapter provides a Guide of Good Practices (GGPs), giving a global vision for addressing a successful RFID implementation project, useful for researchers, developers, and installers.

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