Bitan Banerjee

Greedy Caching: An optimized content placement strategy for information-centric networks

Abstract Most content placement strategies in information-centric networks (ICN) primarily focus on pushing popular content to the network edge, fail to effectively utilize the caches in the network core and provide limited performance improvement. In this paper, we propose Greedy Caching, a content placement strategy that determines the set of content to be cached at each network node so as to maximize the network hit rate. Greedy Caching caches the most popular content at the network edge, recalculates the relative popularity of each piece of content based on the request miss stream from downstream caches and then determines the content to be cached in the network core. We perform exhaustive simulation in the Icarus simulator [1] using realistic Internet topologies (e.g., GARR, GEANT, WIDE, scale-free networks) as well as real-world request stream traces, and demonstrate that Greedy Caching provides significant improvement in content download delay (referred to as latency) over state-of-the-art dynamic caching and routing strategies for ICN for a wide range of simulation parameters. Our simulation results suggest an improvement of 5–28% in latency and 15–50% improvement in hit rate over state-of-the-art policies for synthetic traces.

Content search and routing under custodian unavailability in information-centric networks

Abstract Dealing with the sudden unavailability of content custodians (origin servers) in a network has received limited attention in information-centric networks (ICN). We consider a scenario where the content custodians in an ICN are temporarily unavailable, possibly due to reasons such as device malfunctioning, power outage or Denial of Service (DoS) attacks. In contrast to the traditional host-centric Internet, users can still be served in an ICN as content is cached at in-network nodes. We begin by making the observation that if caches continue to operate using their native cache insertion and eviction policies after the content custodians become unavailable, over time the network content diversity decreases. Therefore, we recommend freezing network caches once the custodians become unavailable. We then propose a routing and search algorithm, Content Exploration under Server Unavailability (CESU), that uses breadcrumbs to effectively locate content cached at in-network nodes and serve user requests when the custodians are unavailable. We perform extensive simulations on real Internet topologies in the Icarus simulator and demonstrate that CESU can efficiently locate content cached in the network. CESU outperforms shortest path routing in terms of content requests served by 56% on average, and achieves up to 98.5% of the total request serving potential.

Generalized Asymptotic Measures for Wireless Fading Channels with a Logarithmic Singularity

In wireless channels, the received signal to noise ratio (SNR) can be represented as amp;#947; = amp;#946;amp;#947;, where amp;#947; is the average SNR and amp;#946; is a random variable with probability density function (PDF) f (amp;#946;). In this paper, we analyze the high SNR performance of wireless channels with a logarithmic singularity. That is, f (amp;#946;) = aamp;#946;t #x002B; bamp;#946;amp;#x00B5; log(amp;#946;) #x002B; amp;#183; amp;#183; amp;#183; near amp;#946; = 0. This logarithmic singularity (LS) is critically important in determining the high SNR performance and appears to have been completely overlooked. Important special cases include Gamma-Gamma and Generalized-K channels. For instance, the GG has been used to model scattering, reflection, and diffraction and optical, navigation and relay channels [1]. This versatility highlights the importance of LS wireless channels. Classical asymptotic or high SNR analysis is developed by expanding f (amp;#946;) = aamp;#946;t #x002B; amp;#183; amp;#183; amp;#183; near amp;#946; = 0 and expressing the diversity and coding gain as direct functions of a and t. However, as this monomial expansion does not hold for LS channels, we develop generalized asymptotic performance measures for outage and error rates. The results show significantly improved accuracy in the SNR range of 10-25 dB. For this range, our new asymptotic expressions achieve much better accuracy than the conventional ones that ignore this singularity.

Study of Mobility in Cache-Enabled Wireless Heterogeneous Networks

Caching popular multimedia content has the potential to take wireless networking to an unprecedented height in terms of user experience. Primary motif behind content caching is to give frequent access to popular content cached at local caches, such as femto access point with finite storage. Although content-caching was Initially limited to wired backbone networks, it now being developed for wireless networks. The main difference between these two cases is the potential mobility of the user. We thus investigate the impact of user mobility on the performance of content-caching wireless heterogeneous networks (HetNets). We describe the user mobility by the random waypoint model and characterize the spatial randomness of different types of nodes by using independent Poisson point processes. Using their stochastic properties, we analyze the handover probabilities and evaluate expected download delay as a function of handover probabilities.

BSMAC: A Hybrid MAC Protocol for IoT Systems

This paper proposes a new medium access control (MAC) protocol for low power sensor devices, suitable for IoT systems. IEEE 802.15.4 standard is suitable for low power wireless personal area network (WPAN) but it does not satisfy the data rate and reliability requirements for IoT systems in a 5G wireless network. We have observed that unnecessary packet drop takes place due to beacon superframe broadcasting during data transmission and it is the primary reason for the standards data-rate and reliability shortfall. This problem represents a scenario where data transmission takes place with the lack of available time for data transmission in that superframe duration. To overcome this lacuna, we incorporate backoff freezing mechanism, where the backoff counter freezes whenever the available time for data transmission is insufficient in that superframe duration. A novel sleep protocol is designed to reduce power consumption in idle states too. The proposed MAC protocol is modeled using a 3- dimensional Markov chain for analytical performance evaluation. Analytical results are verified with the simulation run in ns-2.35. Proposed MAC with sleep protocol significantly outperforms the existing state-of-the-art protocols.

Priority-based content processing with Q-routing in information-centric networking (ICN)

With exponential increase in the number of users and available data, service providers are facing hard times to satisfy and improve end user experience. Researchers have come up with the idea of exploiting increasing number of routers in a network, and it leads to the development of information-centric networking (ICN). Efficient usage of the in-network caches and content forwarding methodology are the key issues in an ICN architecture. ICN reduces average hop count and correspondingly average content download delay because the intra-domain routers in ICN have storage capacity and they can act as temporary content provider. In this paper, we address the content management issue in a cache with finite storage capability and propose an efficient content management policy that changes a router to a self-sustained cache. We propose a novel methodology to process content packets in the buffer of a cache and correspondingly reduce the propagation delay through a cache. We simulate our proposed algorithm over real-life network environment and evaluate the performance of different user experience metrics, e.g. average latency, throughput, goodput, and link load. Simulation results suggest that our proposed model outperforms the existing state-of-the-art on-path caching strategies.