Wireless cache invalidation schemes with link adaptation and downlink traffic

Providing on-demand data access in client-server wireless networks is an important support to many interesting mobile computing applications. Caching frequently accessed data by mobile clients can conserve wireless bandwidth and battery power, at the expense of some system resources to maintain cache consistency. The basic cache consistency strategy is the use of periodic invalidation reports (IRs) broadcast by the server. Recently, IR-based approaches have been further improved by using additional updated invalidation reports (UIRs) (i.e., the IR+UIR algorithm) to reduce the long query latency. However, the performance of the IR+UIR approach in a practical system is still largely unknown. Specifically, previous results are based on two impractical simplifying assumptions: 1 ) broadcast traffic is error-free and 2) no other downlink traffic (e.g., voice) exists in the system. The first assumption is clearly unrealistic as signal propagation impairments (e.g., multipath fading) and, hence, packet reception failures are inevitable in a practical situation. The second assumption is also inapplicable in real life because mobile devices are usually multipurposed (e.g., a mobile phone equipped with a browser may be used for Web surfing while having a phone conversation). In this paper, we first study the performance of the IR+UIR approach under a realistic system model: The quality of the wireless channel is time-varying, and there are other downlink traffics in the system. Our simulation results show that query delay significantly increases as a result of broadcast error and the additional downlink traffics experience longer delay due to extended broadcast period. Exploiting link adaptation (i.e., transmission rate is adjusted dynamically according to channel quality), we then propose three schemes to tackle these two problems. Our results indicate that the proposed schemes outperform IR+UIR under a wide range of system parameters.published_or_final_versio

Design and analysis of channel adaptive wireless cache invalidation strategies with downlink traffic

In this paper, we study the performance of the IR+UIR wireless data cache Invalidation approach under a realistic system model: the quality of the wireless channel Is time-varying; and there are other downlink traffics in the system. Our analysis and simulation results show that query delay significantly increases as a result of broadcast error and the additional downlink traffics experience longer delay due to extended broadcast period. Exploiting link adaptation (i.e., transmission rate is adjusted dynamically according to channel quality), we then propose three schemes to tackle these two problems. Our results Indicate that the proposed schemes outperform IR+UIR under a wide range of system parameters.published_or_final_versio

An Effective Service Mechanism to Achieve Low Query Latency along with reduced Negative Acknowledgement in iVANET: An Approach to Improve Quality of Service in iVANET

The Internet Based vehicular ad hoc network (iVANET) combines a wired Internet and vehicular ad hoc networks (VANETs) for developing a new generation of ubiquitous communicating. The Internet is usually applied in vehicle to infrastructure (V2I) solution whereas ad hoc networks are used in vehicle to vehicle (V2V) communication. Since vehicular networks is characterized by High speed dynamically changing network topology The latency is one of the hot issues in VANET which is proportional to the source-&-remote vehicle distance and the mechanism involved in accessing source memory. If the distance between data source and the remote vehicle is wittily reduced by using redefined caching technique along with certain cache lookup mechanism, the latency is likely to be reduced by a significant factor in iVANET. This paper studies and analyzes various cache invalidation schemes including state of art ones and come with a novel idea of fructifying network performance within the purview of query latency and negative acknowledgement in iVANET. In this paper the roles of the mediatory network component are redefined with associative service mechanism which guarantees reduced query latency as well as minimizes negative acknowledgements in iVANET environment

Cache Invalidation Strategies for Internet-based Vehicular Ad Hoc Networks

Internet-based vehicular ad hoc network (Ivanet) is an emerging technique that combines a wired Internet and a vehicular ad hoc network (Vanet) for developing an ubiquitous communication infrastructure and improving universal information and service accessibility. A key design optimization technique in Ivanets is to cache the frequently accessed data items in a local storage of vehicles. Since vehicles are not critically limited by the storage/memory space and power consumption, selecting proper data items for caching is not very critical. Rather, an important design issue is how to keep the cached copies valid when the original data items are updated. This is essential to provide fast access to valid data for fast moving vehicles. In this paper, we propose a cooperative cache invalidation (CCI) scheme and its enhancement (ECCI) that take advantage of the underlying location management scheme to reduce the number of broadcast operations and the corresponding query delay. We develop an analytical model for CCI and ECCI techniques for fasthand estimate of performance trends and critical design parameters. Then, we modify two prior cache invalidation techniques to work in Ivanets: a poll-each-read (PER) scheme, and an extended asynchronous (EAS) scheme. We compare the performance of four cache invalidation schemes as a function of query interval, cache update interval, and data size through extensive simulation. Our simulation results indicate that the proposed schemes can reduce the query delay up to 69% and increase the cache hit rate up to 57%, and have the lowest communication overhead compared to the prior PER and EAS schemes

Cache Invalidation Strategies for Internet-based Vehicular Ad Hoc Networks

Internet-based vehicular ad hoc network (Ivanet) is an emerging technique that combines a wired Internet and a vehicular ad hoc network (Vanet) for developing an ubiquitous communication infrastructure and improving universal information and service accessibility. A key design optimization technique in Ivanets is to cache the frequently accessed data items in a local storage of vehicles. Since vehicles are not critically limited by the storage/memory space and power consumption, selecting proper data items for caching is not very critical. Rather, an important design issue is how to keep the cached copies valid when the original data items are updated. This is essential to provide fast access to valid data for fast moving vehicles. In this paper, we propose a cooperative cache invalidation (CCI) scheme and its enhancement (ECCI) that take advantage of the underlying location management scheme to reduce the number of broadcast operations and the corresponding query delay. We develop an analytical model for CCI and ECCI techniques for fasthand estimate of performance trends and critical design parameters. Then, we modify two prior cache invalidation techniques to work in Ivanets: a poll-each-read (PER) scheme, and an extended asynchronous (EAS) scheme. We compare the performance of four cache invalidation schemes as a function of query interval, cache update interval, and data size through extensive simulation. Our simulation results indicate that the proposed schemes can reduce the query delay up to 69% and increase the cache hit rate up to 57%, and have the lowest communication overhead compared to the prior PER and EAS schemes

ABMMCCS: Application based multi-level mobile cache consistency scheme

Maintaining cache consistency in mobile computing system is a critical issue due to the inheritance limitations in mobile environment such as limited network bandwidth and mobile device energy power.Most of the existing schemes maintaining mobile cache consistency support only one level of consistency that is either strict or weak which is not suitable all the time, as various mobile applications systems have different consistency requirements on their data.Also majority of the schemes restrict the using of cached data for reading only which is limits the functionality of the caching system.In this paper, a new scheme is proposed to maintain the mobile cache consistency in a single cell wireless network called Application Based Multi-Level Mobile Cache Consistency Scheme (ABMMCCS).The main idea in ABMMCCS is to be suitable to various real mobile application systems, by supporting multiple levels of consistency based on the application requirements, while savingthe mobile client energy power and reducing the consumption of the network bandwidth.The initial evaluation results show that, ABMMCCM reduces the number of uplink messages issued from the mobile client, which is assist in saving the mobile client energy and better utilizing the limited network bandwidth

Model-driven dual caching For nomadic service-oriented architecture clients

Mobile devices have evolved over the years from resource constrained devices that supported only the most basic tasks to powerful handheld computing devices. However, the most significant step in the evolution of mobile devices was the introduction of wireless connectivity which enabled them to host applications that require internet connectivity such as email, web browsers and maybe most importantly smart/rich clients. Being able to host smart clients allows the users of mobile devices to seamlessly access the Information Technology (IT) resources of their organizations. One increasingly popular way of enabling access to IT resources is by using Web Services (WS). This trend has been aided by the rapid availability of WS packages/tools, most notably the efforts of the Apache group and Integrated Development Environment (IDE) vendors. But the widespread use of WS raises questions for users of mobile devices such as laptops or PDAs; how and if they can participate in WS. Unlike their “wired” counterparts (desktop computers and servers) they rely on a wireless network that is characterized by low bandwidth and unreliable connectivity.The aim of this thesis is to enable mobile devices to host Web Services consumers. It introduces a Model-Driven Dual Caching (MDDC) approach to overcome problems arising from temporarily loss of connectivity and fluctuations in bandwidth

Constructing Efficient Cache Invalidation Schemes in Mobile Environments

[[abstract]]Cache invalidation is an effective approach to maintaining data consistency between the server and mobile clients in a mobile environment. This paper presents two new cache invalidation schemes which are designed according to the real situations and are therefore able to comply with the more practical needs in a mobile environment. The ABI+HCQU divides data into different groups based on their utilization rates (hot/cold/query/update) and adapts their broadcasting intervals (ABI) accordingly to suit the actual needs. The SWRCC + MUVI (sleep/wakeup/recovery/check/confirm+modified/uncertain/ valid/ invalid) aims to solve the validity problem of cached data after a client is disconnected from the server. The new cache invalidation schemes are shown through experimental evaluation to outperform most existing schemes in terms of data access time, cache miss rates and bandwidth consumption.[[conferencetype]]國際[[conferencedate]]20071216~20071218[[iscallforpapers]]Y[[conferencelocation]]Shanghai, Chin

On Improving the Robustness of Partitionable Internet-Based Mobile Ad Hoc Networks

Recent technological advances in portability, mobility support, and high speed wireless communications and users' insatiable interest in accessing the Internet have fueled to development of mobile wireless networks. Internet-based mobile ad hoc network (IMANET) is emerging as a ubiquitous communication infrastructure that combines a mobile ad hoc network (MANET) and the Internet to provide universal information accessibility. However, communication performance may be seriously degraded by network partitions resulted from frequent changes of the network topology. In this paper, we propose an enhanced least recently used replacement policy as a part of the aggregate cache mechanism to improve the information accessibility and reduce the access latency in the presence of network partitioning. The enhanced aggregate cache is analyzed and also evaluated by simulation. Extensive simulation experiments are conducted under various network topologies by using three different mobility models: random waypoint, Manhattan grid, and mo -di -fied random waypoint. The simulation results indicate that the proposed policy significantly improves communication performance in varying network topologies, and relieves the network partition problem to a great extent