On the Verification of a WiMax Design Using Symbolic Simulation

In top-down multi-level design methodologies, design descriptions at higher levels of abstraction are incrementally refined to the final realizations. Simulation based techniques have traditionally been used to verify that such model refinements do not change the design functionality. Unfortunately, with computer simulations it is not possible to completely check that a design transformation is correct in a reasonable amount of time, as the number of test patterns required to do so increase exponentially with the number of system state variables. In this paper, we propose a methodology for the verification of conformance of models generated at higher levels of abstraction in the design process to the design specifications. We model the system behavior using sequence of recurrence equations. We then use symbolic simulation together with equivalence checking and property checking techniques for design verification. Using our proposed method, we have verified the equivalence of three WiMax system models at different levels of design abstraction, and the correctness of various system properties on those models. Our symbolic modeling and verification experiments show that the proposed verification methodology provides performance advantage over its numerical counterpart.Comment: In Proceedings SCSS 2012, arXiv:1307.802

On the Verification of a WiMax Design Using Symbolic Simulation

The system-On-Chip design process is continuously increasing in terms of cost and complexity. This imposes new modeling and verification challenges. A particular example is heavy computational applications and functionality, such as digital signal processing and telecommunication applications, which are increasingly integrated in embedded systems nowadays. To meet these challenges, designers use a multilevel model based approach, which is a top-down design methodology where the behavior of the system is first modeled at a higher level of abstraction. Then, design decisions are made to refine those models in a number of transformations until the final product is realized. In this thesis we verify an implementation of a WiMax modem physical layer that has been designed according to the multilevel design approach. This implementation is provided by STMicroelectronics. We propose the utilization of two verification methodologies to verify designs at higher levels of abstraction. The first one is an equivalence checking methodology that is based on symbolic simulation, which provides high speed and computational capabilities. The main purpose of this methodology is to verify the functional equivalence of refined system models in the design process. The second methodology is a property checking approach, which is also based on symbolic simulation. It verifies the conformance of models at different levels of abstraction with the system specification. We verified the equivalence of three models of the WiMax system at different levels of abstraction, and we verified the correctness of various system properties on those models

Communication Subsystems for Emerging Wireless Technologies

The paper describes a multi-disciplinary design of modern communication systems. The design starts with the analysis of a system in order to define requirements on its individual components. The design exploits proper models of communication channels to adapt the systems to expected transmission conditions. Input filtering of signals both in the frequency domain and in the spatial domain is ensured by a properly designed antenna. Further signal processing (amplification and further filtering) is done by electronics circuits. Finally, signal processing techniques are applied to yield information about current properties of frequency spectrum and to distribute the transmission over free subcarrier channels

Multibiometric security in wireless communication systems

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 05/08/2010.This thesis has aimed to explore an application of Multibiometrics to secured wireless communications. The medium of study for this purpose included Wi-Fi, 3G, and WiMAX, over which simulations and experimental studies were carried out to assess the performance. In specific, restriction of access to authorized users only is provided by a technique referred to hereafter as multibiometric cryptosystem. In brief, the system is built upon a complete challenge/response methodology in order to obtain a high level of security on the basis of user identification by fingerprint and further confirmation by verification of the user through text-dependent speaker recognition. First is the enrolment phase by which the database of watermarked fingerprints with memorable texts along with the voice features, based on the same texts, is created by sending them to the server through wireless channel. Later is the verification stage at which claimed users, ones who claim are genuine, are verified against the database, and it consists of five steps. Initially faced by the identification level, one is asked to first present one’s fingerprint and a memorable word, former is watermarked into latter, in order for system to authenticate the fingerprint and verify the validity of it by retrieving the challenge for accepted user. The following three steps then involve speaker recognition including the user responding to the challenge by text-dependent voice, server authenticating the response, and finally server accepting/rejecting the user. In order to implement fingerprint watermarking, i.e. incorporating the memorable word as a watermark message into the fingerprint image, an algorithm of five steps has been developed. The first three novel steps having to do with the fingerprint image enhancement (CLAHE with 'Clip Limit', standard deviation analysis and sliding neighborhood) have been followed with further two steps for embedding, and extracting the watermark into the enhanced fingerprint image utilising Discrete Wavelet Transform (DWT). In the speaker recognition stage, the limitations of this technique in wireless communication have been addressed by sending voice feature (cepstral coefficients) instead of raw sample. This scheme is to reap the advantages of reducing the transmission time and dependency of the data on communication channel, together with no loss of packet. Finally, the obtained results have verified the claims

Key distribution technique for IPTV services with support for admission control and user defined groups

Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200

WiMAX spectrum virtualization and network federation

Spectrum management in wireless broadband networks as regards its cost and its efficient usage has posed a huge challenge for mobile network operators. Traditionally, network operators had exclusive rights to access the band of spectrum allocated to them, but with the high price of spectrum license, it is becoming necessary to find alternative ways to use and access spectrum more efficiently. Resource virtualization is a method which has been extensively adopted in hardware computing for creating abstract versions of physical hardware resources and it has proven to be a powerful technique for customized resource provision and sharing. This idea of resource virtualization is gradually being transferred into the domain of wireless mobile network resource management but the ideas around it are still evolving. Since spectrum is an important wireless network resource, it is imperative to provide an efficient and cost effective means for the resource to be accessed and utilized. Therefore the idea of spectrum virtualization is investigated in this research as a possible solution to this problem. To expand on the notion of spectrum virtualization, this research further explores the idea of network federation. Network Federation involves the interconnection of diverse network components to be operated as a single seamless network. This will enable them share their network resources while the networks are geographically dispersed and managed by different network operators. To fully implement these concepts there is a need for a well-developed network framework. This research proposes two novel architectures for spectrum virtualization and network federation using the WiMAX (Worldwide Interoperability for Microwave Exchange) wireless broadband technology. The proposed WiMAX spectrum virtualization architecture introduces a novel entity known as the Virtual Spectrum Hypervisor (VS-Hypervisor). This VS-Hypervisor bears the responsibility of spectrum management and virtualization within the WiMAX framework. In the implementation of WiMAX network federation, the novel architecture enables the cooperative existence of multiple WiMAX base-stations having virtualization capabilities with overlapping cellular coverage areas for the purpose of sharing their spectrum resources. In this architecture, a novel federation control plane known as the Virtual Spectrum Exchange Locale (VSEL) is proposed. The VSEL facilitates the VS-Hypervisors in the federated physical base-stations to be able to negotiate and exchange spectrum between themselves to match their spectrum needs. The architectures for WiMAX spectrum virtualization and network federation was modelled and implemented using the OPNET Modeler. Results obtained validated their efficacy with respect to the effective management of the wireless network spectrum. Therefore this proposed network architectures would help network operators optimize their radio networks

Planning and dynamic spectrum management in heterogeneous mobile networks with QoE optimization

The radio and network planning and optimisation are continuous processes that do not end after the network has been launched. To achieve the best trade-offs, especially between quality and costs, operators make use of several coverage and capacity enhancement methods. The research from this thesis proposes methods such as the implementation of cell zooming and Relay Stations (RSs) with dynamic sleep modes and Carrier Aggregation (CA) for coverage and capacity enhancements. Initially, a survey is presented on ubiquitous mesh networks implementation scenarios and an updated characterization of requirements for services and applications is proposed. The performance targets for the key parameters, delay, delay variation, information loss and throughput have been addressed for all types of services. Furthermore, with the increased competition, mobile operator’s success does not only depend on how good the offered Quality of Service (QoS) is, but also if it meets the end user’s expectations, i.e., Quality of Experience (QoE). In this context, a model for the mapping between QoS parameters and QoE has been proposed for multimedia traffic. The planning and optimization of fixed Worldwide Interoperability for Microwave Access (WiMAX) networks with RSs in conjunction with cell zooming has been addressed. The challenging case of a propagation measurement-based scenario in the hilly region of Covilhã has been considered. A cost/revenue function has been developed by taking into account the cost of building and maintaining the infrastructure with the use of RSs. This part of the work also investigates the energy efficiency and economic implications of the use of power saving modes for RSs in conjunction with cell zooming. Assuming that the RSs can be switched-off or zoomed out to zero in periods when the traffic exchange is low, such as nights and weekends, it has been shown that energy consumption may be reduced whereas cellular coverage and capacity, as well as economic performance may be improved. An integrated Common Radio Resource Management (iCRRM) entity is proposed that implements inter-band CA by performing scheduling between two Long Term Evolution – Advanced (LTE-A) Component Carriers (CCs). Considering the bandwidths available in Portugal, the 800 MHz and 2.6 GHz CCs have been considered whilst mobile video traffic is addressed. Through extensive simulations it has been found that the proposed multi-band schedulers overcome the capacity of LTE systems without CA. Result shown a clear improvement of the QoS, QoE and economic trade-off with CA

Security-centric analysis and performance investigation of IEEE 802.16 WiMAX

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