Cross-layer Optimization for the Coexistence of Mobile and Wireless Networks Beyond 3G

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Publications

Cost/Revenue Tradeoff in the Optimization of Fixed WiMAX Deployment With Relays

Publication . Velez, Fernando J.; Nazir, Muhammad Kashif; Aghvami, A. Hamid; Holland, Oliver; Robalo, Daniel

In fixed Worldwide Interoperability for Microwave Access (WiMAX), the contribution from each transmission mode can be incorporated into an implicit formulation to obtain the supported throughput as a function of the carrier-to-interference ratio. This is done by weighting the physical throughput in each concentric coverage ring by the size of the ring. In this paper, multihop cells are formed by a central coverage zone and three outer coverage zones, which are served by cheaper low-complexity relays. Although the reuse distance in this case is augmented by a factor of √3, we show that, with the use of relays in frequencydivision duplexing (FDD) mode with an adapted time-division duplexing (TDD) uplink (UL) subframe structure to accommodate communication from/to the relay station (RS) to/from subscriber station (SS), only the consideration of trisectored base stations (BSs) with a reuse pattern of K = 3enables attainment of values for the cell per sector throughput that is comparable with cases without the use of relays. Cost/revenue optimization results show that trisectored BSs in topologies with relays enable us to achieve more profitable reuse configurations than with omnidirectional BSs and no relays. Under the same total bandwidth and with the coverage distance set at R ∼ 500 m, we show that it is preferable to consider K = 1 with three carriers per sector instead of K = 3with one carrier per sector, whereby the profit in this case is increased from ∼1000% to ∼1450%. Furthermore, if the price [in (C/MB)] is increased from 0.0025 to 0.005, the achievable profit more than doubles.

2011-01Journal article

Open access

Unified propagation model for Wi-Fi, UMTS and WiMAX planning in mixed scenarios

Publication . Varela, Frederico; Sebastião, Pedro; Correia, Americo; Cercas, Francisco; Rodrigues, António; Velez, Fernando J.; Robalo, Daniel

This paper presents an unified and empirical propagation model to obtain the received power in mixed scenarios, with outdoor and indoor environments, or in a scenario with only one kind of environment, either for an urban, sub-urban or rural scenario, with or without vegetation. This unified model is called the Lisbon University Institute (LUI) one and can be included into planning tools for wireless communication systems. The developed model is suitable for Path Loss prediction in mobile, as well as fixed wireless network systems, e.g., Wireless Fidelity, Universal Mobile Telecommunications System and Worldwide Interoperability for Microwave Access, considering Line-of-Sight or Non-Line-of-Sight propagation conditions.

2010-09Conference object

Open access

Validation of the unified propagation model for Wi-Fi, UMTS and WiMAX planning

Publication . Varela, Frederico; Sebastião, Pedro; Correia, Americo; Cercas, Francisco; Rodrigues, Antonio; Velez, Fernando J.; Robalo, Daniel

This paper presents the validation of the unified propagation model, the Lisbon University Institute (LUI) model, which is valid for three wireless technologies: Wireless Fidelity, Universal Mobile Telecommunications System and Worldwide Interoperability for Microwave Access. With this purpose in mind, several experimental trials for those technologies were performed in different scenarios, where mixed environments (outdoor and indoor) were included. This generalized and unified propagation model was tuned by adjusting specific parameters for each different technology, based on the achieved results from the field experiments.

2010-09Conference object

Open access

Business Models and Cost/Revenue Optimization

Publication . Velez, Fernando J.; Nazir, Muhammad Kashif; Aghvami, A. Hamid; Holland, Oliver; Robalo, Daniel

This Chapter starts by covering general aspects about the business models for WiMAX and then addresses the cost/revenue optimization for these networks, for cellular configurations without and with relays. In Fixed WiMAX, radio and network planning can be optimised by tuning a cost/revenue function which incorporates de the cost of building and maintaining the infrastructure and the effect of the available resources on revenues. From the cost-benefit analysis, one conclusion of this work is that given today’s hypothesis of price per MByte of information transfer of somewhere between 0.0025 € and 0.010 €, it is clear that, without considering the use of relays, the choice of reuse patterns 3 or 4 with sectorial cells is preferable to the use of omnidirectional cells with reuse pattern, K, of 7, as three times more resources are available in each cell. Besides, in nowadays networks, if there is a need for sparse BS deployments whilst reducing costs, K = 1 may be a solution, as it presents higher profit for the longest coverage distances. In future networks, when costs will be lower, the advantage of sectorization is kept and will drive the deployment of tri-sectorization forward. Nevertheless, in this case K = 1 will not be advantageous with tri-sectorization for the longest coverage distances anymore. This study also concludes that cell radii in the range 1000–1500m is preferable, corresponding to profit in percentage terms of near the achievable maximum, while keeping costs acceptable. The WiMAX cost-benefit optimization is also explored for the case where relays are used to help on improving coverage while mitigating the interference. Results show that the use of relays with no sectorization in the BS leads to a lower profit (K = 3). Also the use of sectorization (an example is presented for K = 1) does not seem to enable larger profit. The optimum (maximum) values occur for coverage distances up to 1,000 m. In the DL, when the price per MB, R144, increases from 0.0025 €/min to 0.005 €/min the profit increases more than 100%.

2010Book part

Open access

Interoperability Between IEEE 802.11e and HSDPA: Challenges from Cognitive Radio

Publication . Cabral, Orlando Manuel Brito; Ferro, João Miguel; Velez, Fernando J.

In this chapter we propose a scenario for interoperability between high-speed downlink packet access (HSDPA) and Wi-Fi. This scenario involves the end-user traveling in a public transportation system and requesting multimedia services to the operator. The interoperability between HSDPA and Wi-Fi (IEEE 802.11e standard) radio access technologies (RATs) is first addressed, a topology in which the user has access to both RATs was considered, together with a common radio resource management (CRRM) to manage the connections. We reached the conclusion that the CRRM enables to increase the system throughput when the load thresholds are set to 0.6 for HSDPA and 0.53 for Wi-Fi. Then, spectrum aggregation is implemented in HSDPA. A resource allocation (RA) algorithm allocates user packets to the available radio resources (in this case Node Bs operating at 2 and 5 GHz are available) in order to satisfy user requirements. Simulation results show that gains up to 22% may be achieved. We have also sought the most efficient way to manage routing packets inside the Wi-Fi network. The proposal which uses links with higher throughputs enables to reach the best results, with gains up to 300% in the packet delivery ratio. Finally, we discuss the challenges that need to be addressed in order to materialise the envisaged cognitive radio scenario in public transportation.

2011Book part

Open access