Heterogeneous Networks and IEEE 1905

To address the challenging issues of energy-efficiency and seamless connectivity in heterogeneous networks, 3GPP and IEEE have recently incorporated several architectural and functional enhancements to the baseline operation of their standards for cellular and wireless local area network access, respectively. Based on the 3GPP Access Network Discovery and Selection Function (ANDSF) and the advanced measurement capabilities provided by the IEEE 802.11-2012 and the 3GPP Long Term Evolution - Advanced (LTE-A) Standards, we propose an ANDSF-assisted energy-efficient vertical handover decision algorithm for the heterogeneous IEEE 802.11-2012 / LTE-A network. The proposed algorithm enables a multi-mode mobile terminal to select and associate with the network point of attachment that minimizes its average overall power consumption and guarantees a minimum supported quality of service for its ongoing connections. System-level simulation is used to evaluate the performance of the proposed algorithm and compare it to that of other competing solutions.

To address the challenging issues of energy-efficiency and seamless connectivity in heterogeneous networks, 3GPP and IEEE have recently incorporated several architectural and functional enhancements to the baseline operation of their standards for cellular and wireless local area network access, respectively. Based on the 3GPP Access Network Discovery and Selection Function (ANDSF) as well as the advanced measurement capabilities provided by the IEEE 802.11-2012 and the 3GPP Long Term Evolution–Advanced (LTE-A) Standards, we propose an ANDSF-assisted energy-efficient vertical handover decision algorithm for the heterogeneous IEEE 802.11-2012 / LTE-A network. The proposed algorithm enables multi-mode mobile terminals to select and associate with the network point of attachment that minimizes the average overall power consumption at the mobile terminal and guarantees a minimum supported quality of service for its ongoing connections. System-level simulations demonstrate the performance of the proposed algorithm and compare it against that of other competing solutions.

Distributed transmission rate tuning is important for a wide variety of IEEE 802.15.4 network applications such as industrial network control systems. Such systems often require each node to sustain certain throughput demand in order to guarantee the system performance. It is thus essential to determine a proper transmission rate that can meet the application requirement and compensate for network imperfections (e.g., packet loss). Such a tuning in a heterogeneous network is difficult due to the lack of modeling techniques that can deal with the heterogeneity of the network as well as the network traffic changes. In this paper, a distributed transmission rate tuning algorithm in a heterogeneous IEEE 802.15.4 CSMA/CA network is proposed. Each node uses the results of clear channel assessment (CCA) to estimate the busy channel probability. Then a mathematical framework is developed to estimate the on-going heterogeneous traffics using the busy channel probability at runtime. Finally a distributed algorithm is derived to tune the transmission rate of each node to accurately meet the throughput requirement. The algorithm does not require modifications on IEEE 802.15.4 MAC layer and it has been experimentally implemented and extensively tested using TelosB nodes with the TinyOS protocol stack. The results reveal that the algorithm is accurate and can satisfy the throughput demand. Compared with existing techniques, the algorithm is fully distributed and thus does not require any central coordination. With this property, it is able to adapt to traffic changes and re-adjust the transmission rate to the desired level, which cannot be achieved using the traditional modeling techniques.

Environment monitoring is key for multiple applications and requires that devices used in acquiring environment data to be scattered over a wide area, but at the same time maintain accessibility of information from all sensor nodes. Although many Wireless Sensor Networks are based on the IEEE 802.15.4 standard for low-power, Wi-Fi networks offer the most accessibility and interoperability with other devices. We envision a system which integrates the two networks' main capabilities by monitoring data in a heterogeneous Wireless Sensor Network. Nodes can transmit sensor data over the Internet to other devices, server applications or cloud based solutions, making the whole process of environmental monitoring universally accessible.

The new medium access method of IEEE 802.11ah, called restricted access window (RAW), divides stations into different groups, and only allows stations in the same group to access the channel simultaneously, in order to reduce collisions and thus achieve better performance (e.g., throughput). However, the existing station grouping strategies only support homogeneous scenarios where all stations use the same modulation and coding scheme (MCS) and packet size. A surrogate model is an efficient mathematical model that represents the behavior of a complex system, trained with a limited set of labeled input–output data samples. In this article, we present a surrogate model that can accurately predict RAW performance under a given RAW configuration in heterogeneous networks. Different from the homogeneous scenario, heterogeneous networks are defined by a large number of parameters, leading to an enormous design space, i.e., the order of 1017 possible data points. This is too big to achieve feasible training convergence. In this article, we present a novel training methodology that leads to a new design space with highly reduced size, i.e., the order of 105 data points. The surrogate model converges when less than 6000 labeled data points are used for training, which is only a tiny portion of the whole design space. The results show that, the relative error between model prediction and simulation results is less than 0.1 for 95% of the data points, in the areas of the design space studied. Its low complexity and high precision make the proposed model a valuable tool to develop real-time RAW optimization algorithms for heterogeneous IEEE 802.11ah networks.

Distributed throughput optimization for heterogeneous IEEE 802.11 DCF networks

Wireless networks are becoming increasingly popular. These wireless solutions range from personal networks (e.g. Bluetooth), through local (e.g. WiFi) and metropolitan area networks (e.g. WiMax) up to the cellular networks that offer the coverage almost everywhere. As the number of different wireless technologies grows, a unified and standardized mobility support algorithm for heterogeneous networks is needed. The paper evaluates the performance of mobility support mechanisms and algorithms offered by a new IEEE 802.21 standard. The heterogeneous scenario with UMTS and IEEE 802.11 networks is modeled and investigated. The handover in both directions is discussed, taking into account implementation of MIH Link Going Down event for IEEE 802.11 networks, proposed by the authors. This event is used to optimize handover from IEEE 802.11 network to UMTS networks. The new, proposed in the paper solution, makes it possible to support multimedia services during the heterogenous handovers. To verify the proposed algorithm the simulation environment has been defined, based on ns-2 simulator. The number of experiments was performed to evaluate the packets lost ratio and the delays introduced by heterogenous handover.

The development of new network communication protocols has to include a process of concept evaluation in order to prove its soundness. Simulation-based techniques provide assessment of communication quality in complex and realistic working conditions. This paper introduces a novel and unique simulation technique, by merging QualNet simulator and SDL protocol developer. Many complex modifications of the QualNet nodes can be efficiently implemented, which is very difficult by a straightforward re-coding of QualNet components. The proposed methodology was utilized in the development of a wireless heterogeneous IEEE 802.21-based network. The paper provides a detailed insight of the model's three basic parts: QualNet environment, SDL resource manager and the novel SDL2QualNet interface. We present useful information for 802.21 simulation implementation, data acquisition from QualNet and calculation of dynamic network parameters, information and buffer management, methods for improvement of simulation efficiency, and many other modeling hints which enable a comprehensive simulation platform.

As various radio access technologies and multi-mode terminals incorporating multiple network interfaces appear, research and development interest on heterogeneous network interworking increases. IEEE 802 groups have standardized technologies on interworking between heterogeneous IEEE 802 networks and between an IEEE 802 network and a cellular network. This paper analyzes technologies on heterogeneous network interworking of IEEE 802 standards and provides trends and requirements of future technology on heterogeneous network interworking.