A new multi-rat scheduling algorithm for heterogeneous wireless networks

Next Generation Wireless Networks (NGWNs) are expected to be heterogeneous, which integrate different Radio Access Technologies (RATs) such as 3GPP's Long Term Evolution (LTE) and Wireless Local Area Networks (WLANs) where a transmission is supported if the signal-to-interference-plus-noise ratio (SINR) at the receiver is greater than some threshold. In this paper, we analyze the interference in heterogeneous wireless networks and determine the capacity by taking into consideration the class of traffic of each call and considering both intra-network interference and inter-network interference. This analysis allows us to simplify the estimation of capacity under SINR interference constraints in different wireless networks.

Next generation wireless network (NGWN) will be heterogeneous where different radio access technologies (RATs) coexist. In NGWN, efficient radio resource management and QoS provisioning are major challenges. We propose an optimal joint radio resource management algorithm to minimize call blocking probability in NGWN. The algorithm makes call admission decisions such that overall call blocking probability is minimized in the heterogeneous wireless network. We develop an analytical model for the radio resource management algorithm using a multi-dimensional Markov chain. Based on linear programming optimization technique, we determine the optimal splitting of arriving calls among available RATs. Results show that the proposed algorithm outperforms other algorithm in the heterogeneous wireless network.

It is envisaged that next generation wireless networks (NGWN) will be heterogeneous, consisting of multiple radio access technologies (RATs) coexisting in the same geographical area. In these heterogeneous wireless networks, mobile terminals of different capabilities (heterogeneous terminals) will be used by subscribers to access network services. We investigate the effect of using heterogeneous mobile terminals (e.g. single-mode, dual-mode, triple-mode, etc.) on call blocking and call dropping probabilities in cooperative heterogeneous wireless networks. We develop analytical models for heterogeneous mobile terminals and joint radio resource management in heterogeneous wireless networks. Using a two-class three-RAT heterogeneous wireless network as an example, the effect of using heterogeneous terminals in the network is evaluated. Results show the overall call blocking/dropping probability experienced by subscribers in heterogeneous wireless networks depends on the capabilities of mobile terminals used by the subscribers. In the worst case scenario, when all subscribers use single-mode mobile terminals, each subscriber is confined to a single RAT and consequently, joint radio resource management in heterogeneous wireless network has no improvement on new call blocking and handoff call dropping probabilities. However, in the best case scenario, when all subscribers use three-mode terminals, new class-1 call blocking probability decreases from 0.37 (for 100% single-mode terminals) to 0.05, at the arrival rate of 6 calls per minute. New class-2 call blocking probability also decreases from 0.8 to 0.52. Similarly, handoff class-1 call dropping probability decreases from 0.14 to 0.003, and handoff class-2 call dropping probability decreases from 0.44 to 0.09.

A major challenge of the heterogeneous wireless networks is how to jointly utilize the resources of different radio access technologies (RATs) in an efficient manner while simultaneously achieving the desired multi-service quality of service (QoS) and minimizing the service cost. To meet the challenge, this paper proposes an adaptive common radio resource management (CRRM) scheme in the context of wireless wide area network (WWAN) and wireless local area network (WLAN). The key parameters of the scheme are service type, user mobility and location information, load information, and service cost. The effectiveness of the proposed CRRM scheme is assessed analytically using the theory of Markov chains. Numerical results show that the proposed scheme minimizes the rate of unnecessary vertical handoffs (VHO), thereby providing stable communication without degrading call blocking performance and increasing service cost.

The progressive adaptability of today’s mobile communication services and the prompt progressions in the mobile phones industry have steered to a remarkable development in the wireless market capacity. Notwithstanding the incessant advancement in the radio access technologies to manage with that growth. However, many remaining challenges, i.e., inefficient allocation and management of wireless network resources in Heterogeneous Wireless Networks (HWNs) when using the modern cellular mobile communications radio access technologies such as Wireless Local Area Network (WLAN)/Wi-Fi, Long-TERA Evolution (LTE) and Fifth Generation (5G)) still continue and needs to be addressed. This problem emanates from the enormous number of users sharing these resources, random distribution of wireless channels, scarceness of the wireless spectral resources, and the dynamic behavior of generated traffic. Therefore, this paper solves the identified problem by designing an Efficient Resource Allocation (ERA) algorithm to address the inefficient allocation of available resources versus quality of service (QoS) challenges. The obtained simulation results demonstrate the effectiveness of the proposed model to meet the objectives subject to limitations and constraints compared to other published works. On average, the proposed ERA algorithm, Joint Power Bandwidth Allocation (JPBA) algorithm, and Dynamic Bandwidth Allocation (DBA) algorithm have shown 98.9%, 85%, 81% throughput performance, respectively at a time interval of 100s.

Modern network technologies first evolved in wired networks and subsequently entered the wireless network field. Applications may work in pure wired network, pure wireless network or hybrid network. Improving performance in these network infrastructures has been a continuous effort for decades. In this dissertation, we tackle two important challenges: (1) improving handover performance in heterogeneous wireless network, and (2) improving TCP performance in multi-hop wireless network. In heterogeneous network, users expect uninterrupted services moving from one network to another. IEEE proposed Media Independent Handover (MIH) to make it possible to achieve better handover performance. Currently, Mobile IPv4 (MIP) is the dominant mechanism for mobility management and is expected to persist into the future. However, when multiple interfaces of a mobile client are connected to a Foreign Agent (FA), MIP and its existing improvements do not perform well when the active interface fails unexpectedly. In this dissertation, we propose novel mechanism and MIP extension with MIH support. We prove experimentally that the new approach eliminates the FA-HA latency and achieves much faster handover, compared with existing mechanism. Our method also allows FA-bicasting, which can improve transmission reliability by combining traffic from different links, through the same FA. In multi-hop wireless networks, the main network factor that affects TCP performance is the medium-access contention, complicated by other factors like hidden terminal. We analyze the TCP congestion window and provide a more accurate estimate of its optimal value than those reported in the prior work. We also show that the much shorter TCP-ACK packets consume comparable channel capacity as the much longer data packets. We therefore propose two methods to improve TCP throughput, as follows. (1) Segregate the flows of data and ACK using static routing in grid wireless network, (2) Develop an improved variant of delayed TCP ACK by minimizing the number of ACK packets. Our evaluation validates the effectiveness of the proposed method, which can enhance TCP performance significantly. In terms of throughput, it achieves up to 204% improvement over the regular TCP in chain-topology wireless networks, and about 35% improvement in a complex grid wireless network. We also propose a new architecture to achieve higher throughput when multiple TCP connections exist.

In next-generation (NG) wireless networks, hybrid handover techniques are expected to enable the integration of heterogeneous networks, e.g. 3G cellular networks and 802.11 wireless LAN (WLAN). Media independent handover (MIH) has begun to be discussed in the latest IEEE 802.21 to accommodate multiple disparate interfaces in mobile handset. Multiple interfaces can come in a variety of ways to facilitate hybrid handover, and may result in different requirements on protocols and performance. In this paper, we classify multi-interface schemes for handover in heterogeneous wireless networks. We propose a multi-interface scheme for IEEE 802.21 MIH. The scheme is proposed to be able to work with standard TCP and Mobile IPv4 agent routers without particular configuration. Based on this scheme, we implemented a dual-interface Mobile Host (MH) model in Network Simulation 2 (ns2) to evaluate how it performs in comparison with single-interface MH.

In this paper we investigate the impact of a Relay Node (RN) placement plan on a heterogeneous wireless network called Hybrid Wireless Network with dedicated delay nodes (HWN*) in terms of system capacity, transmission delay and Quality of Service (QoS). A novel HWN* Heuristic RN Placement (HHRP) algorithm, which considers RN assistance & support for radio resource sharing such as inter-network traffic balancing, TD/CDMA soft handover, routing and user mobility has been implemented. A system level simulation is used to quantify the benefits of HWN* using HHRP algorithm over HWN* with other RN placement plans and multi-hop cellular networks. I. INTRODUCTION A heterogeneous wireless network refers to a wireless net- work that is comprised of wireless nodes with different radio access technologies or equipment with different operating systems. For example, it can be a wireless sensor network including bluetooth based radio access and zigbee 802.15.4 based radio access or a hybrid wireless network including cellular access and 802.11b/g based radio access. Specifi- cally for a hybrid wireless network, the increase of cellular communication intensity results in a reduction in cell size, thus much denser clusters are required resulting in increased infrastructure cost and system complexity. Meanwhile, the bursty nature of communication traffic and path loss results in traffic prediction difficulty. A solution must be found to provide effective resource management, congestion control and routing. The hybrid wireless network which incorporates cellular and MANET interfaced RELAY nodes, provides a practical approach for this. Nevertheless, the dedicated relay infrastructure approach can be also be adapted to the emerging wireless sensor network in order to maintain node connectivity, support sensor data aggregation and optimise power consump- tion.

Next generation wireless networks (NGWN) will be heterogeneous, comprising a number of radio access technologies (RATs) coexisting in the same geographical area. In NGWN, a joint call admission control (JCAC) algorithm is needed to select the most appropriate RAT for each incoming call. The JCAC algorithm must be user-centric (i.e., consider user preferences in making RAT selection decisions) in order to enhance userspsila satisfaction. This paper investigates a user-centric JCAC (UJCAC) algorithm for heterogeneous wireless networks. The UJCAC algorithm uses Fuzzy multiple-attribute decision-making technique to select the most appropriate RAT for each incoming call. We develop a Markov model for the UJCAC algorithm to evaluate the overall call blocking probability and handoff call dropping probability in heterogeneous wireless networks. Performance of the UJCAC algorithm is evaluated using a three-RAT heterogeneous network. Simulation results show that a UJCAC algorithm can lead to highly unbalanced network load, and high call blocking/dropping probability. Therefore, a flexible UJCAC algorithm is more suitable for NGWN. In flexible UJCAC, if the mostly preferred RAT for incoming call is fully loaded, the next preferred RAT will be selected for the call. The call will be blocked only if none of the available RATs can accommodate the call. Therefore, call blocking/dropping probability will be reduced.

Wireless networking is a crucial component of communication in this era of digitization. The key characteristics that determine a wireless network's performance are smooth connectivity, quicker communication, and increased customer satisfaction. Scalability deals with the erratic workload and new resources that are added to the network. Scalability is crucial for both Quality of Experience (QoE) and Quality of Service (QoS) in such a power-constrained environment because wireless devices are battery-operated. Managing power consumption and network performance simultaneously in scalable networking scenario is quite challenging, especially during handover. This research proposed a methodology to assess the impact of scalability on wireless node power consumption and network performance in order to develop energy-efficient handoff mechanisms. The Type-I and Type-II wireless node sets were used between the WiFI and WiMAX networks in a vertical handover scenario. In the study, two distinct scalability scenarios were taken into account. Three distinct voltage levels—cutoff voltage, nominal voltage, and charge voltage —had been used to examine the consumption of power. Throughput, residual energy, and Packet Delivery Ratio (PDR) were computed to examine the network's performance in a scalable, power-constrained context. Two different scalability scenarios were considered in the study. The power consumption was investigated using three different voltage levels: charge voltage, nominal voltage, and cutoff voltage. The network's performance under scalable, power-constrained conditions was investigated by computing throughput, packet delivery ratio (PDR), and residual energy. The result obtained in the study showed the variation in battery drainage of wireless nodes under the effect of various scalability factors. This study will provide a blueprint for developing novel algorithms which eventually will improvise network performance and strengthen the base of Green Networking.

There is an increasing demand for high bandwidth-consuming services such as real-time video and video streaming over wireless access networks. A single radio access technology (RAT) in a heterogeneous wireless network may not always have enough radio resource to admit high bandwidth-consuming calls, such as video calls. Existing joint call admission control (JCAC) algorithms designed for heterogeneous wireless networks block/drop an incoming call when none of the available individual RATs in the network has enough bandwidth to admit the incoming call. Consequently, video calls experience high call blocking/dropping probability in the network. However, some calls such as multi-layer coded (scalable) video can be transmitted/received over one or multiple RATs. This article proposes a JCAC algorithm that selects a single or multiple RATs for scalable video calls in heterogeneous wireless networks, depending on availability of radio resources in available RATs. Non scalable calls are always admitted into a single RAT by the algorithm. The aim of the proposed algorithm is to reduce call blocking/dropping probability for both scalable and non-scalable calls. An analytical model is developed for the proposed JCAC algorithm, and its performance is evaluated. Simulation results show that the proposed algorithm reduces call blocking/dropping probability in heterogeneous wireless networks.

Particle swarm optimization application for multiple attribute decision making in vertical handover in heterogenous wireless networks

The ever increasing user QoS demands and emergence of new user applications make job of network operators and manufacturers more challenging for efficiently optimisation and managing radio resources in radio the radio resources pools of different wireless networks. A group of strategies or mechanisms which are collectively responsible for efficient utilisation of radio resources available within the Radio Access Technologies (RAT) are termed as Radio Resource Management (RRM). The traditional RRM strategies are implemented independently in each RAT, as each RRM strategy considers attributes of a particular access technology. Therefore traditional RRM strategies are not suitable for heterogeneous wireless networks. Common Radio Resource Management (CRRM) or joint radio resource management (JRRM) strategies are proposed for coordinating radio resource management between multiple RATs in an improved manner. In this paper a fuzzy algorithm based CRRM strategy is presented to efficiently utilise the available radio resources in heterogeneous wireless networks. The proposed CRRM strategy balances the load in heterogeneous wireless networks and avoids the unwanted congestion situation. The results such as load distribution, packet drop rate and average throughput at mobile nodes are used to demonstrate the benefits of load balancing in heterogeneous wireless networks using proposed strategy.

Heterogeneous wireless network (HWN) is an overlay structure of different wireless networks (WN). The WNs may differ in terms of coverage, capacity, underlying technology, service types, and network operators. In such a HWN environment, a mobile user (MU) equipped with multi-mode or multi-home terminal always wish to maintain connectivity with a wireless network which can provide best quality of experience (QoE). Similarly, the WN may allow the connectivity only to a MU which can provide highest revenue. This may leads to an event, called vertical handoff, where the MU leaves current WN and connect to another different WN. The conflicting goals of maximizing QoE and revenue simultaneously while performing a VHO necessitates the selection of mutually best MU and WN. Game theory is an efficient mathematical tool to model such situations where specific actions of decision makers lead to mutually conflicting consequences to each other. This paper, using a tutorial style, presented the game theory concepts and its application for VHO, type of games, and game solutions. It proposes, in specific, the noncooperative game formulations for three different VHO situations and their solutions using NASH for HWNs.

In this paper we present a novel, comprehensive and standalone SDL-based model for performance analysis and planning of IEEE 802.11a Wireless Local Area Networks (WLANs). We have developed our model using the obtainable code from the IEEE 802.11 standards committee, with all necessary improvements to provide efficient tool for simulation of the IEEE 802.11a WLANs. We have verified the developed simulator through extensive simulations targeted to Medium Access Control layer and physical layer, which has shown that it can be used as an efficient tool in analysis, planning and optimization of 802.11a wireless networks for different types of services and for different environments.