Melchizedek I. Alipio

Analysis of cache-based transport protocol at congestion in Wireless Sensor Networks

Consistent data delivery in constrained networks such as wireless sensor networks (WSN), which has a significant role in Internet of Things (IoT), is vital due to the high probability of packet loss, not only because of the unreliable channel but also from link and buffer congestions. Thus, a reliable transport protocol should be used. Data caching at intermediate nodes is one way of improving the reliability performance of transport protocols in WSNs. However, it is not yet known up to what extent data caching alone can alleviate congestion in WSNs. This study investigates and analyses how a cache-based transport protocol, that has no congestion control mechanism and has a fixed transmission window, performs under congestion states. The transport protocol, called DTSN, is evaluated under link and buffer congestion states and the optimal performance is determined in terms of goodput, transmission cost and cache hit metrics. The results of our analysis reveal that intermediate caching was able to perform significantly during congestions in WSN. However, the amount of traffic being sent and intermediate nodes cache memory should be taken into account. The optimum caching performance during link contentions is reached at higher transmission window and cache size values, while for buffer congestions, it is achieved at lower transmission window but higher cache size values, respectively. These values obtained can guarantee optimum usage of cache while ensuring congestion avoidance. In addition, the correlation that is established can serve as a basis for developing congestion window management for transport protocols in WSN that employ data caching.

Cache-based transport protocols in wireless sensor networks

Sensor nodes in Wireless Sensor Networks (WSNs) are battery-powered devices that consume energy during data transmission and processing. One of the most critical tasks in a sensor network is dealing with reliable end-to-end transmissions and optimizing the power consumption. WSNs are error prone due to the constrained nature of the nodes and the interference with other wireless technologies such as Wifi and Bluetooth. One possible way to minimize this problem is caching the data. Data caching is one technique of improving the performance of a transport protocol. Since a typical data transmission consumes more energy than processing in a sensor network, the use of caching enables quick access to data. Therefore, caching, if used efficiently, could reduce overall network traffic and hence bandwidth can be optimally utilized. Unfortunately, a systematic analysis of caching in WSNs was until now lacking. Given that WSNs are expected to play an important role in Machine Type Communications (MTC) and Internet of Things (IoT), the authors believe that now is time to collect the results of years of research on this important topic. This paper presents a comprehensive survey on the state-of-the-art cache-based transport protocols in wireless sensor networks. We classify the transport protocols by presenting a thematic taxonomy of the current cache management mechanisms in wireless sensor networks. Moreover, the critical aspects of the existing cache-ware schemes in sensor networks are analyzed to determine the strengths and weaknesses of such protocols. The similarities and differences of the transport protocols based on the important parameters, such as cache insertion/replacement policy, cache size requirement, cache location, cache partition, and cache decision are investigated in this paper. In addition to that, we discuss open research issues and challenges of cache-based transport protocols in wireless sensor networks. We strongly believe that this study can serve as a basis so that future implementations can choose the combination of caching mechanisms that best fits their target application scenario.

Improving reliable data transport in wireless sensor networks through dynamic cache-aware rate control mechanism

Data delivery in low power and lossy networks like Wireless Sensor Networks (WSN), which has a significant role in Internet of Things (IoT), is vital due to the high probability of packet loss due to wireless and constrained environment. Data caching and transmission rate control are independent ways of improving the performance of transport protocols in WSN by immediately responding to packet losses in the network. However, a suitable rate control for cache-based transport protocols is not yet investigated. This work developed a dynamic cache-aware rate control algorithm that uses a transmission window rate as a function of cache size allocation used by intermediate nodes and utilizes cache elimination policy to notify packet losses in the network. A baseline cache-based transport protocol called DTSN+ is used to implement the rate control algorithm and evaluated under different network scenarios. Results show that the cache-aware approach improves the performance of the baseline transport protocol during high level of packet losses in the network in terms of cache utilization especially at lower cache size value. The algorithm also obtained outstanding throughput, transmission time and fairness performance as compared with original DTSN+ and DTC protocols. In the future, these results can serve as an underlying support in designing a new cache-aware congestion control framework that can be integrated in a transport protocol to mitigate packet losses in WSN.

Towards a taxonomy of cache-based transport protocols in wireless sensor networks

Sensor nodes in Wireless Sensor Networks (WSNs) are battery-powered devices that consume energy during data transmission and processing. One of the most critical tasks in a sensor network is to deal with optimizing the power consumption. One possible way to minimize this problem is caching the data. Data caching is a promising technique for improving the performance of transport protocols in terms of reliability in most sensor applications. Since, a typical data transmission consumes more energy than processing in a sensor network, the use of caching enables quick access to data. Therefore, caching, if used efficiently, could reduce overall network traffic and hence bandwidth can be optimally utilized. Unfortunately, a systematic treatment of caching in WSNs was until now lacking. Given that WSNs are expected to play an important role in Internet of Things (IoT) and wireless sensing applications, the authors believed that now is time to collect the results of years of research on this important topic. This paper presents a thematic taxonomy of the current cache management mechanisms of transport protocols in wireless sensor networks. The similarities and differences of the transport protocols based on the important parameters, such as cache insertion/replacement policy, cache size requirement, cache location, cache partition, and cache decision are investigated in this paper. In addition to that, we discuss open research issues and challenges of implementing intermediate caching to various sensor deployment. In the future, this study can be a basis so that future implementations can choose the combination of caching mechanisms that best fits their target in the field of instrumentation and measurements, especially in WSN applications.

Demonstration of Quality of Service mechanism in an OpenFlow testbed

In this paper, a realtime testbed for Software Defined Networks (SDN) was implemented using Raspberry Pi as OpenFlow (OF) switches. The implemented testbed provides practical development and testing environment for SDNs. Open vSwitch (OVS) was used to observe the flows and events in the network. With the POX integration, this paper easily provide detailed analysis results for any testing process. Additionally, this study implemented priority queuing algorithm, which manages the flows with respect to their QoS requirements. Priority queuing is a scheduling mechanism that provides a fixed number of priority levels to different service classes and can be used for differentiated services provisioning. Differentiated service is a QoS architecture that seeks to provide service differentiation to a small number of service classes. Finally, this study physically implemented the proposed algorithm to our testbed and validate the improvements of traffic and network utilization in terms of throughput.

A Cache-Aware Congestion Control for Reliable Transport in Wireless Sensor Networks

Data caching and congestion control are two strategies that can enhance the transport reliability in constrained Wireless Sensor Networks. However, these two mechanisms are designed independently for most transport protocols developed for WSN. This work developed a new cache-aware congestion control mechanism for reliable transport. RT-CaCC utilizes cache management policies such as cache insertion, cache elimination and cache size to mitigate packet losses in the network while maximizing cache utilization and resource allocation. It uses two cache management policies for packet loss detection: implicit notifications and expiration of timeout. In addition, it utilizes congestion avoidance using cache-aware rate control mechanism employing transmission window limit as a function of cache size. Results showed that the RT-CaCC obtained significant improvement gain in terms of cache utilization, end-to-end delay and throughput performance specifically during high level of packet loss in the network.

Dynamic Source Rate Control for Cache-Based Transport Protocol in Wireless Sensor Networks

Abstract Reliability of data transport in low power and lossy networks like Wireless Sensor Networks (WSN) is vital due to its constraint characteristics and high probability of packet loss from wireless environment and congestion. Data caching and transmission rate control mechanisms are independent ways of improving the reliability of transport protocols in WSN as they immediately respond to packet losses in the network. However, these two mechanisms are traditionally designed independently and an appropriate rate control that can potentially improve the performance of cache-based transport protocols has not yet been investigated. In this work, a dynamic source rate control algorithm that utilizes a cache-aware approach was developed wherein cache management policies are employed to notify the relative degree of packet losses and limit the transmission window size. A baseline cache-based transport protocol called DTSN + is used to implement the rate control algorithm and evaluated under network scenarios that experience packet losses from contention and congestion. The dynamic cache-aware algorithm outperformed other transport protocols in terms of cache utilization by 30%. The algorithm also obtained outstanding throughput, transmission time and fairness performance as compared with the fixed DTSN + and DTC protocols. This demonstrated that a cache-aware approach can improve the performance of a transport protocol during high levels of packet losses in the network. In the future, these results can serve as an underlying support in designing a new cache-aware congestion control framework that is suitable for transport protocols that employ the use of intermediate caching in WSN.