Real Test Bed Experiments Research Articles

Analysis of the effectiveness of transmission power control as a location privacy technique

Location privacy is an increasing source of concern for wireless users since their positions can be unwittingly estimated by malicious eavesdroppers. Transmission power control (TPC) is one of the various obfuscation techniques mentioned in the literature with the potential to provide location privacy to wireless users. This technique consists of letting the user vary the mobile node’s transmission power in a way that only the nearest eavesdropper can overhear the mobile node’s signals. This variation reduces the number of eavesdroppers overhearing the mobile node’s transmissions, thus increasing the location error estimated by nearby eavesdroppers, thereby improving the mobile user’s location privacy. Although some works have highlighted the advantages of TPC as a location privacy technique, no previous work has studied its effectiveness considering wireless channel impairments, hardware limitations, and localization algorithms used by eavesdroppers. This paper analyzes the real value of using TPC as a location privacy technique through a probabilistic model that measures the ability of TPC to effectively reduce the number of overhearing eavesdroppers. The results presented in this work show that the effectiveness of TPC is considerably affected by wireless channel impairments as well as by eavesdroppers’ density. Moreover, since off-the-shelf 802.11 radios have limited transmission power levels, real test-bed experiments showed that mobile users cannot always adjust their transmission power to fulfill the required levels of TPC. This is particularly the case in densely deployed scenarios in which most of the time the required transmission power is below the radio’s minimum transmission level. These results demonstrate the limited location privacy capabilities of TPC in most real-life scenarios, thus disproving previous claims that place TPC as a solution for the location privacy problem.

A Dynamic Application-Partitioning Algorithm with Improved Offloading Mechanism for Fog Cloud Networks

This paper aims to propose a new fog cloud architecture that performs a joint energy-efficient task assignment (JEETA). The proposed JEETA architecture utilizes the dynamic application-partitioning algorithm (DAPTS), a novel algorithm that efficiently decides and switches the task to be offloaded or not in heterogeneous environments with minimal energy consumption. The proposed scheme outperforms baseline approaches such as MAUI, Think Air and Clone Cloud in many performance aspects. Results show that for the execution of 1000 Tasks on fog, mobile offloaded nodes, JEETA consumes the leas, i.e., 23% of the total energy whereas other baseline approaches consume in between 50%–100% of the total energy. Results are validated via real test-bed experiments and trice are driven efficient simulations.

Delay sensitive resource allocation over high speed IEEE802.11 wireless LANs

We present a novel resource allocation framework based on frame aggregation for providing a statistical Quality of Service (QoS) guarantee in high speed IEEE802.11 Wireless Local Area Networks. Considering link quality fluctuations through the concept of effective capacity, we formulate an optimization problem for resource allocation with QoS guarantees, which are expressed in terms of target delay bound and delay violation probability. Our objective is to have the access point schedule down-links at minimum resource usage, i.e., total time allowance, while their QoS is satisfied. For implementation simplicity, we then consider a surrogate optimization problem based on a few accurate queuing model approximations. We propose a novel metric that qualitatively captures the surplus resource provisioning for a particular statistical delay guarantee, and using this metric, we devise a simple-to-implement Proportional–Integral–Derivative (PID) controller achieving the optimal frame aggregation size according to the time allowance. The proposed PID algorithm independently adapts the amount of time allowance for each link, and it is implemented only at the Access Point without requiring any changes to the IEEE802.11 Medium Access Control layer. More importantly, our resource allocation algorithm does not consider any channel state information, as it only makes use of queue level information, such as the average queue length and link utilization. Via NS-3 simulations as well as real test-bed experiments with the implementation of the algorithm over commodity IEEE 802.11 devices, we demonstrate that the proposed scheme outperforms the Earliest Deadline First (EDF) scheduling with maximum aggregation size and pure deadline-based schemes, both in terms of the maximum number of stations and channel efficiency by 10–30%. These results are also verified with analytical results, which we have obtained from a queuing model based approximation of the system. Applying actual video traffic from HD MPEG4 streams in both simulations and real test-bed experiments, we also show that our proposed algorithm improves the quality of video streaming over a wireless LAN, and it outperforms EDF and deadline based schemes in terms of the video metric, Peak Signal to Noise Ratio.

A Cross-Layer Channel Access and Routing Protocol for Medical-Grade QoS Support in Wireless Sensor Networks

One of principal design issues of a Wireless Sensor Network (WSN) for medical information systems is to classify received packets based on their priorities and guarantees so that they can be transmitted reliably, thus satisfying QoS requirements. In addition, when the target WSN requires multi-hop communications and the traffic load increases significantly, it is challenging to support both load balancing and suitable QoS at the same time. In this paper, we propose a new reliable protocol termed Cross-layer Channel Access and Routing (CCAR), which simultaneously supports both MAC and routing operations for medical-grade QoS provisions. CCAR initially determines the routing path with the lowest traffic load and low latency using newly defined channel quality factors. Concurrently, the source node allocates the predefined QoS Access Category to each packet and reserves the channel along the route. In addition, CCAR introduces an effective route maintenance scheme to avoid link failures in bottlenecked intermediate nodes, which prevents unnecessary packet drops and route rediscovery evocations. Finally, through both simulation studies and real test-bed experiments, we evaluate the performance of CCAR by comparing it with other conventional protocols, demonstrating that the proposed protocol can more efficiently support medical-grade QoS packets, especially when the network is heavily loaded.

Perpetual and Fair Data Collection for Environmental Energy Harvesting Sensor Networks

Renewable energy enables sensor networks with the capability to recharge and provide perpetual data services. Due to low recharging rates and the dynamics of renewable energy such as solar and wind power, providing services without interruptions caused by battery runouts is nontrivial. Most environment monitoring applications require data collection from all nodes at a steady rate. The objective of this paper is to design a solution for fair and high throughput data extraction from all nodes in the presence of renewable energy sources. Specifically, we seek to compute the lexicographically maximum data collection rate and routing paths for each node such that no node will ever run out of energy. We propose a centralized algorithm and two distributed algorithms. The centralized algorithm jointly computes the optimal data collection rate for all nodes along with the flows on each link, the first distributed algorithm computes the optimal rate when the routing structure is a given tree, and the second distributed algorithm, although heuristic, jointly computes a routing structure and a high lexicographic rate assignment that is nearly optimum. We prove the optimality for the centralized and the first distributed algorithm, and use real test-bed experiments and extensive simulations to evaluate both of the distributed algorithms.

Optical Networks Functional Evolution and Control Technologies

In this paper the current trends in the optical networking including the physical components, technologies and control architectures are discussed. The possible interaction schemes and implementation models of the automatic communication between applications and network as well as between ASON/GMPLS based network domains are proposed. Finally, the related research activities based on simulation results of control plane dimensioning are illustrated and real test bed experiments on OIF worldwide interoperability demonstration and the ongoing European 1ST project MUPBED are disseminated.