Handoff Triggering and Network Selection Algorithms for Load-Balancing Handoff in CDMA-WLAN Integrated Networks

This paper proposes a novel vertical handoff algorithm between WLAN and CDMA networks to enable the integration of these networks. The proposed vertical handoff algorithm assumes a handoff decision process (handoff triggering and network selection). The handoff trigger is decided based on the received signal strength (RSS). To reduce the likelihood of unnecessary false handoffs, the distance criterion is also considered. As a network selection mechanism, based on the wireless channel assignment algorithm, this paper proposes a context-based network selection algorithm and the corresponding communication algorithms between WLAN and CDMA networks. This paper focuses on a handoff triggering criterion which uses both the RSS and distance information, and a network selection method which uses context information such as the dropping probability, blocking probability, GoS (grade of service), and number of handoff attempts. As a decision making criterion, the velocity threshold is determined to optimize the system performance. The optimal velocity threshold is adjusted to assign the available channels to the mobile stations. The optimal velocity threshold is adjusted to assign the available channels to the mobile stations using four handoff strategies. The four handoff strategies are evaluated and compared with each other in terms of GOS. Finally, the proposed scheme is validated by computer simulations

Optimizing Network Access Selection in Wireless Heterogeneous Networks using Velocity, Location, Policy and Qos Details

As the interest in 4G communication systems continues to grow, both academia and industry agree that a symbiotic relationship between various wireless systems is required to provide continuous broadband coverage to mobile users. It is generally accepted that a single wireless access technology alone will be incapable of meeting the various requirements of mobility, data rate and coverage in the future. Future wireless systems are envisioned as being heterogeneous in that they will include a combination of various wireless access technologies such as 3G, WLAN, and WiMAX and will have a common IP core. To fully utilize the various resources and maintain seamless connectivity in the future heterogeneous wireless environment, intelligent handoff schemes that are flexible, scalable and proactive are essential. Therefore, a new handoff decision method, one that works in a novel business model--Heterogeneous Wireless Service Provider (HWSP)--was developed with an aim to improve the mobile user's user experience. More effort was spent to achieve a good level of user satisfaction, by making the entire selection process automatic, and the user oblivious of the underlying network selection intricacies. The algorithm is able to make the final network decision, based on any particular user's speed, location, QoS demands and preference policies. This allows the algorithm to prevent unwanted handoffs and reduce the cost associated with connecting to suboptimal networks

Comparison of vertical handover decision-based techniques in heterogeneous networks

Industry leaders are currently setting out standards for 5G Networks projected for 2020 or even sooner. Future generation networks will be heterogeneous in nature because no single network type is capable of optimally meeting all the rapid changes in customer demands. Heterogeneous networks are typically characterized by some network architecture, base stations of varying transmission power, transmission solutions and the deployment of a mix of technologies (multiple radio access technologies). In heterogeneous networks, the processes involved when a mobile node successfully switches from one radio access technology to the other for the purpose of quality of service continuity is termed vertical handover or vertical handoff. Active calls that get dropped, or cases where there is discontinuity of service experienced by mobile users can be attributed to the phenomenon of delayed handover or an outright case of an unsuccessful handover procedure. This dissertation analyses the performance of a fuzzy-based VHO algorithm scheme in a Wi-Fi, WiMAX, UMTS and LTE integrated network using the OMNeT++ discrete event simulator. The loose coupling type network architecture is adopted and results of the simulation are analysed and compared for the two major categories of handover basis; multiple and single criteria based handover methods. The key performance indices from the simulations showed better overall throughput, better call dropped rate and shorter handover time duration for the multiple criteria based decision method compared to the single criteria based technique. This work also touches on current trends, challenges in area of seamless handover and initiatives for future Networks (Next Generation Heterogeneous Networks)

Непрерывная вертикальная передача обслуживания в гетерогенных беспроводных сетях с использованием алгоритма модифицированной оптимизации удаления ненужных данных

Полный текст доступен на сайте издания по подписке: http://radio.kpi.ua/article/view/S0021347017100028В глобальном контексте существует большое количество сетей с беспроводным доступом. В гетерогенных беспроводных сетях используются различные типы реализаций, включая работу в реальном масштабе времени, работу в нереальном масштабе времени и работу с высокой пропускной способностью, поэтому провайдер услуг связи должен обеспечить поддержку соответствующих соединений. Для улучшения рабочих характеристик, соединения должны коммутироваться между различными сетями с использованием непрерывной вертикальной передачи обслуживания VHO (vertical handoff). Предложенный алгоритм обеспечивает улучшение, обусловленное методом оптимизации, который включает процесс решения о коммутации с использованием запуска VHO и выбора сети. Запуск VHO инициируется путем использования уровня принятого сигнала RSS (received signal stregth). В случае использования традиционного метода, запуск VHO инициируется только с помощью RSS. Предложенный метод, представляющий собой алгоритм модифицированной оптимизации удаления ненужных данных M-WO (modified weed optimization), сокращает ненужные VHO путем учета как RSS, так и скорости мобильного узла при запуске VHO. Для достижения эффективности процесса выбора сети необходимо учитывать индивидуально или совместно следующие параметры: срок службы аккумуляторной батареи, процент сорванных звонков при передаче обслуживания, нагрузку, адаптацию по методу динамических весовых коэффициентов и т.п. В этой работе показан новый эффект алгоритма M-WO для принятия решения при VHO. Усилия авторов направлены на существенную оптимизацию нагрузки системы с тем, чтобы уменьшить процент сорванных звонков при VHO и потребление энергии аккумуляторной батареей мобильного узла MN (mobile node). Вес каждого показателя QoS подстраивается в соответствии с изменяющимися условиями работы сетей для отслеживания M-WO. Таким образом, предложенный алгоритм принятия решения при VHO превосходит существующие методы SSF и OPTG. Результаты моделирования показали, что эффективность алгоритма M-WO выше эффективности методов SSF и OPTG в отношении нагрузки, процента сорванных звонков при передаче обслуживания и срока службы батареи MN

Resource Allocation for Cellular/WLAN Integrated Networks

The next-generation wireless communications have been envisioned to be supported by heterogeneous networks using various wireless access technologies. The popular cellular networks and wireless local area networks (WLANs) present perfectly complementary characteristics in terms of service capacity, mobility support, and quality-of-service (QoS) provisioning. The cellular/WLAN interworking is thus an effective way to promote the evolution of wireless networks. As an essential aspect of the interworking, resource allocation is vital for efficient utilization of the overall resources. Specially, multi-service provisioning can be enhanced with cellular/WLAN interworking by taking advantage of the complementary network strength and an overlay structure. Call assignment/reassignment strategies and admission control policies are effective resource allocation mechanisms for the cellular/WLAN integrated network. Initially, the incoming calls are distributed to the overlay cell or WLAN according to call assignment strategies, which are enhanced with admission control policies in the target network. Further, call reassignment can be enabled to dynamically transfer the traffic load between the overlay cell and WLAN via vertical handoff. By these means, the multi-service traffic load can be properly shared between the interworked systems. In this thesis, we investigate the load sharing problem for this heterogeneous wireless overlay network. Three load sharing schemes with different call assignment/reassignment strategies and admission control policies are proposed and analyzed. Effective analytical models are developed to evaluate the QoS performance and determine the call admission and assignment parameters. First, an admission control scheme with service-differentiated call assignment is studied to gain insights on the effects of load sharing on interworking effectiveness. Then, the admission scheme is extended by using randomized call assignment to enable distributed implementation. Also, we analyze the impact of user mobility and data traffic variability. Further, an enhanced call assignment strategy is developed to exploit the heavy-tailedness of data call size. Last, the study is extended to a multi-service scenario. The overall resource utilization and QoS satisfaction are improved substantially by taking into account the multi-service traffic characteristics, such as the delay-sensitivity of voice traffic, elasticity and heavy-tailedness of data traffic, and rate-adaptiveness of video streaming traffic

A Seamless Vertical Handoff Protocol for Enhancing the Performance of Data Services in Integrated UMTS/WLAN Network

The Next Generation Wireless Network (NGWN) is speculated to be a unified network composed of several existing wireless access networks such as Wireless Local Area Network (WLAN), Global System for Mobile (GSM), Universal Mobile Telecommunications System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX), and satellite network etc

Improved Vertical Handoff Schemes for K-Tier Heterogeneous Wireless Network

The vertical hando_ schemes for heterogeneous wireless networks are presented in the thesis. A heterogeneous network consists of multiple tiers of available wireless net-works, framed as K-tier heterogeneous wireless network (KHWN). A typical KHWN adopted in the thesis consists of Global System for Mobile communication (GSM), Universal Mobile Telecommunications System (UMTS), Wireless Local Area Network (WLAN) and Long Term Evolution (LTE). The hando_ scheme considers the Receiv- ing Signal Strength (RSS)and Signal to Interference and Noise Ratio (SINR) with the tra_c cost as the key parameters for vertical hando_ decision making process. The key parameter RSS is estimated through a proposed path loss model based on local terrain and is observed to be better as compared to the earlier empirical models. With the local terrain input, the path loss model and RSS has been estimated for GSM, UMTS, WLAN and LTE networks. Following this a VHO scheme is proposed for voice and data communication. Subsequently this SINR and a KHWN consisting of multi-tier with the four types of services viz. voice call, video streaming, web brows- ing and telemetry are considered. In this multi-hierarchy decision making process the best suited Analytical and Hierarchical Process (AHP) is applied, for the decision making process in VHO. The proposed scheme of vertical hando_ provides higher QoS than the earlier algorithms of Combined SINR based Vertical Hando_ (CSVH) and Multi-dimensional SINR based vertical hando_ (MSVH). Also the unnecessary VHO are controlled by the proposed scheme. The result shows that the proposed scheme provides low cost tra_c and overall system throughput with a control of unnecessary hando_s for all kinds of services within the KHWN

SCALABLE AND EFFICIENT VERTICAL HANDOVER DECISION ALGORITHMS IN VEHICULAR NETWORK CONTEXTS

A finales de los años noventa, y al comienzo del nuevo milenio, las redes inalámbricas han evolucionado bastante, pasando de ser sólo una tecnología prometedora para convertirse en un requisito para las actividades cotidianas en las sociedades desarrolladas. La infraestructura de transporte también ha evolucionado, ofreciendo comunicación a bordo para mejorar la seguridad vial y el acceso a contenidos de información y entretenimiento. Los requisitos de los usuarios finales se han hecho dependientes de la tecnología, lo que significa que sus necesidades de conectividad han aumentado debido a los diversos requisitos de las aplicaciones que se ejecutan en sus dispositivos móviles, tales como tabletas, teléfonos inteligentes, ordenadores portátiles o incluso ordenadores de abordo (On-Board Units (OBUs)) dentro de los vehículos. Para cumplir con dichos requisitos de conectividad, y teniendo en cuenta las diferentes redes inalámbricas disponibles, es necesario adoptar técnicas de Vertical Handover (VHO) para cambiar de red de forma transparente y sin necesidad de intervención del usuario. El objetivo de esta tesis es desarrollar algoritmos de decisión (Vertical Handover Decision Algorithms (VHDAs)) eficientes y escalables, optimizados para el contexto de las redes vehiculares. En ese sentido se ha propuesto, desarrollado y probado diferentes algoritmos de decisión basados en la infraestructura disponible en las actuales, y probablemente en las futuras, redes inalámbricas y redes vehiculares. Para ello se han combinado diferentes técnicas, métodos computacionales y modelos matemáticos, con el fin de garantizar una conectividad apropiada, y realizando el handover hacia las redes más adecuadas de manera a cumplir tanto con los requisitos de los usuarios como los requisitos de las aplicaciones. Con el fin de evaluar el contexto, se han utilizado diferentes herramientas para obtener información variada, como la disponibilidad de la red, el estado de la red, la geolocalizaciónMárquez Barja, JM. (2012). SCALABLE AND EFFICIENT VERTICAL HANDOVER DECISION ALGORITHMS IN VEHICULAR NETWORK CONTEXTS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/17869Palanci