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- Cost/revenue performance in an IMT-Advanced scenario with Spectrum Aggregation over non-contiguous frequency bandsPublication . Acevedo Flores, Jessica Elizabeth; Velez, Fernando J.; Cabral, Orlando; Robalo, Daniel Luís Silveira; Holland, Oliver; Aghvami, A. Hamid; Meucci, Filippo; Mihovska, Albena Dimitrova; Prasad, Neeli R.; Prasad, RamjeeThis paper determines the cost/revenue performance of a mobile communication system in an IMT-Advanced scenario with integrated Common Radio Resource Management (iCRRM). The iCRRM performs classic CRRM functionalities jointly with Spectrum Aggregation (SA), being able to switch users between non-contiguous frequency bands. The SA scheduling is obtained with an optimized General Multi-Band Scheduling (GMBS) algorithm with the aim of cell throughput maximization. In particular, we investigate the dependence of the throughput on the cell coverage distance for the allocation of users over the 2 and 5 GHz bands for a single operator scenario under a constant average Signal to Interference-plus-Noise Ratio (SINR), for the same type of Radio Access Technology and both frequency bands. The operator has the availability of a non-shared 2 GHz band and has access to part (or all) of a shared frequency band at 5 GHz. An almost constant gain near 30 % was obtained with the proposed optimal solution compared to a system where users are first allocated in one of the two bands and later not able to handover between the bands. It is shown that the profit in percentage terms decreases as the cell radius increases. These results allow for evaluating the impact of the revenue from the channel in the total revenue and in the profit, defined as the difference between revenues and costs, in percentage. Maximum profits of about 1270, 585 and 240 % have been obtained for prices of 0.10, 0.05 and 0.025 €/MByte, respectively, when iCRRM is employed, while profits of 990, 440, and 170 % have been reached with no iCRRM, i.e., simple CRRM. Finally, an energy efficiency strategy is proposed and analyzed, showing that there is significant transmission power saving potential through the opportunistic reallocation scheme.
- Cost/revenue optimization of WiMAX networks with relay power saving modes: Measurement-Based scenario in a hilly regionPublication . Velez, Fernando J.; Oliveira, João; Robalo, Daniel; Holland, Oliver; Aghvami, HamidThis paper investigates cell zooming and relaying in conjunction with the use of opportunistic sleep modes to save energy at times of low load in WiMAX network deployments. It performs extensive propagation measurements in a hilly area of Covilhã, Portugal, in order to present a realistic and topographically challenging scenario in which to perform dynamic optimizations. It describes these measurements and their methodology in detail. Based on this scenario, it then investigates the performance achievable by networks that are deployed in various sectorization configurations with and without relays, and matches this to varying traffic loads at different times of the day to maximise the use of sleep modes, where possible, by relays, also in consideration of coverage constraints. Results demonstrate that savings typically of 47.6% in relays' average power consumption can be achieved. These savings are shown to map to a financial saving for the operator of 10% in operation and maintenance cost combined. It is also demonstrated that such solutions have to be used cautiously in such hilly regions due to challenges in maintaining coverage.
- Pluralistic licensingPublication . Holland, Oliver; De Nardis, Luca; Nolan, Keith; Medeisis, Arturas; Anker, Peter; Minervini, Leo Fulvio; Velez, Fernando; Matinmikko, Marja; Sydor, JohnWe introduce the concept of “pluralistic licensing”, which we describe as the award of licenses under the assumption that opportunistic secondary spectrum access will be allowed, and that interference may be caused to the primary with parameters and rules that are known to the primary at the point of obtaining the license. A key aspect of the concept is that the primary will choose from a range of offered “pluralistic licenses” each with associated fees, and each specifying alternative opportunistic access rules and associated interference characteristics. Our proposal is a novel means to take forward spectrum licensing which is fair to both primary and secondary users and takes into account the requirements of both parties. The objective is to incentivize the primary to obtain this type of license through means such as a reduced license fee, whereby the opportunistic secondary spectrum access will use “cognitive radio” mechanisms to avoid causing interference to the primary or to otherwise keep interference within known parameters. We discuss that our proposed concept can propel more robust or better design of both primary and secondary devices. For primary devices it can lead to the ability to cope with an increased degree or risk of interference among other benefits, and for secondary devices might lead to the ability to better share spectrum opportunities. Both of these aspects greatly improve spectrum usage efficiency and fairness. Our concept is also highly flexible dependent on the case-by-case deployment context, even so far as allowing solutions such as spectrum sensing and primary beacon transmissions which would otherwise not be practical or desirable, while defaulting to safe mechanisms such as a geolocation database in cases where a lower interference variance is required. Many other benefits of our concept and its extensions are discussed. We argue that “pluralistic licensing” should become the de facto form of license awarded in newly designated bands, and should also be offered to the primary as a licensing option in existing bands in cases where interference to legacy devices that might exist in the band can be avoided.