This paper suggests that the regulatory tool known as the Block Edge Mask (BEM), which is used to define the technical conditions governing a spectrum license, can be used as an instrument to jointly drive spectrum and energy efficiency in a network. The paper explores this concept and goes on to show how networks can generate waveforms which comply with the energy limits of the BEM and at the same time make best use of the spectral resources available to them. The focus of the paper is on orthogonal frequency division multiplexing (OFDM) waveforms. The spectrum- and energy-efficient BEM-compliant waveforms are generated using a process that optimally combines symbol shaping and subcarrier-power loading to create a waveform that minimizes the difference between the transmitted wave and BEM. Practical considerations relating to peak-to-average-power-ratio (PAPR) reduction and time and frequency synchronization issues are explored to ensure the BEM-compliant waveforms can be transmitted with minimal changes to the transceiver. It is envisaged that these techniques will be used by transmitters that change their frequency of operation and in doing so need to shape their transmitted waveforms to comply with the different BEMs governing the use of the different spectrum blocks they wish to access.

The purpose of this paper is to present a vision for future mobile and wireless networks. The vision, which we call Networks without Borders (NwoB), is based on a marketplace of virtual network operators which construct networks from a pool of shared resources (e.g., base stations, spectrum, core network components, cloud resources, processing capabilities, etc.). The resources will be sourced from traditional industry players as well as crowdsourced from individuals. The paper describes this approach from a value-chain perspective. The proposed value chain is substantially different from the value-chain models that are currently used to illustrate mobile and wireless networks. The economic imperatives and innovation drivers for this approach are discussed. Early work showing the promise of this vision is presented. This work focuses on diverse examples which advocate the removal of traditional and historical restrictions on spectrum and infrastructure and move toward more dynamic use of shared resources. In the first example, we look at how frequency-division-duplexing (FDD) and time-division-duplexing (TDD) restrictions on spectrum usage can be relaxed; we remove the borders between TDD and FDD. In the second example, we look at the aggregation and pooling of corporate infrastructure which uses exclusive spectrum and removes the borders between different mobile operators. Finally, we look at the aggregation of user-deployed or crowdsourced infrastructure that opportunistically uses spectrum and removes the borders between independently deployed hotspots. These are starting points, and the full realization of the vision will involve more dynamic access to spectrum and more extensive sharing of infrastructure. Hence, the final part of the paper describes the resulting research challenges.

In this paper we explore a means of allowing independent service providers using whatever spectrum they can find, to come together in a loose form of coalition which supports mobility between service providers. The service providers are not required to use similar network configurations- i.e. they can configure to best suit their needs and in line with what spectrum they find available. Our solution involves the use of what we term a cyclostationary codec which in essence is a physical pattern that can be placed in the control channel of the service provider. This pattern is the key enabling mechanism for identifying the coalition, enabling rendezvous, supporting handover and conveying details of the service provider configuration.

This paper focuses on a solution for a spectrum access system that can be deployed in the 3.5 GHz band to enable sharing of these bands between existing incumbents and new small cell systems. The FCC envisages some kind of dynamic data base as a means of supporting this sharing. In this paper we recommend that the database should support the use of adaptive spectrum masks, defined at the cell level, to control the emissions of the systems sharing the bands. The severity of the mask is context dependent and hence the least restrictive mask rather than one that represents a worst case scenario is used. Calculating the least restrictive spectrum mask in a context dependent manner involves examining an infinite number of potential scenarios. Our solution makes use of a pixelated database which results in large but finite no of possibilities and therefore converts the problem to a tractable one. A library of masks, each one corresponding to a specific scenario, is then stored in theh database. The fact that users must register with the database to access spectrum means it is possible to determine the distribution and density of users (i.e. the context). and retrieve the best mask. This will allow for far more efficient use of the spectrum then in a traditional system while still guaranteeing a certain QoS for the users.

This paper considers spatial spectrum sharing-based carrier aggregation (SSS-CA) from a game theoretic perspective. In SSS-CA, a network operator can not only transmit on its own licensed spectrum but it can also access and aggregate the licensed spectrum of other operators on payment of a certain price. The difference between operators and the aggregators in each licensed spectrum makes this network heterogeneous. We first model the pairing problem between potential operators as a pairing game and then derive the condition for which both operators are incentivized to form an SSS-CA pair. We then introduce the power control game to derive the optimal transmit power of each spectrum aggregator. Finally, we consider the pricing optimization problem by forming a pricing adjustment game. We observe that these three problems are linked by the price function of the operators and hence can be jointly optimized by using a hierarchical game theoretic framework. We derive the Stackelberg equilibrium for the pricing and power joint optimization problem and present the numerical results to compare the performance improvement brought by our proposed joint optimization method.

This paper considers the use of a recently developed Bayesian statistical approximation technique that leads to very fast determination of highly accurate estimates for latent radio signal power. Following suitable data analysis, a first order non-stationary auto-regressive process is considered for latent radio signal and the fast approximation technique is then used to provide accurate estimates of the hidden model parameters. These estimates are based on having received several noisy, but spatially correlated, observations of the true latent signal. The implication of this technique for real time decision analysis and the problem of finding, and making use of, so-called radio spectrum holes is also discussed.

The performance evaluation of ad hoc network components through simulation allows for isolation of parameters, easy access to global quantities and a statistically significant number of repeatable trials. In designing network protocols, it is important to investigate the relationship between global network performance and the underlying locally observed network characteristics. Mobility models are used to define the movement of nodes in the simulation space. A wide variety of mobility models exist, and the choice of mobility model has significant influence over locally observed metrics. Unfortunately, many mobility models exhibit spatial and temporal non-stationarity of important metrics, such that global averages of certain metrics are not representative of local observations. This finding impacts on the development of adaptive ad hoc architectures. This paper explores the spatial stationarity of frequently used mobility models. It focuses on the importance of stationarity in relation to the evaluation of performance studies. The spatial non-stationarity of link statistics, and the impact of this artefact on network performance evaluation is examined for the Toroidal Random Waypoint and Random Direction mobility models. We show that the Toroidal Random Waypoint model exhibits spatial stationarity of link statistics. Furthermore, we demonstrate that network performance studies in spatially stationary environments produce dissimilar results to those produced by non-stationary environments. This shows the importance of spatial stationarity when investigating global network performance and locally observed network characteristics.

The dynamic nature of ad hoc networks advocates the use of adaptive schemes to optimize network performance. Such adaptive schemes require local observations of prevailing network conditions. This paper discusses the dependencies between locally observable metrics. The probability density functions for link statistic metrics are assessed, and the implications of the distribution model for parametric inference is investigated.

This paper describes a self-stabilizing protocol which enables the reactive auto-configuration of multi-protocol mobile ad hoc network nodes. The spatially and temporally diverse nature of ad hoc networks suggests the development of a more sophisticated network-layer that enables the network's nodes to choose their preferred routing protocol from an array of protocols with varying abilities. However, the configuration of such a dependent variable, and one with network-wide significance, is a non-trivial task in a distributed system. This paper focuses on the problems that arise in developing a configuration protocol which does not compromise the inherent distributed, open and infrastructure-independent traits of an ad hoc networking system. Self-stabilization is identified in this paper as a suitable technique on which to base such a robust and distributed autonomous configuration protocol. The protocol takes the form of a stateless configuration initialisation (SCl) protocol which is coupled with a configuration conflict detection & resolution (CCDR) protocol.