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A predictive handoff mechanism for 5G ultra dense networks

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A predictive handoff mechanism for 5G ultra dense networks

IEEE International Symposium on Network computing and Applications

作者： Shankar K. Ghosh Sasthi C. Ghosh Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata India

The fifth generation (5G) ultra dense network (UDN) is envisioned as a very dense deployment of low power base stations where heterogeneous radio access technologies are used to satisfy the data rate demand of users employing both licensed and unlicensed spectrum. In UDN scenario, conditions of the channels operating in licensed band may exhibit intermittent characteristics due to the varying level of interference received from large number of nearby access networks. On the other hand, channel conditions in unlicensed band may fluctuate drastically due to the interference caused by the co-existence of long term evolution (LTE-U) and wireless local area network (WLAN) in unlicensed band. The traditional handover mechanisms rely on the instantaneous assessments of link qualities such as RSS and SINR. The target network selected based on such instantaneous values may not be the appropriate one when the actual handover is executed. In this work, we have proposed a predictive handover mechanism which can estimate achievable throughput values from different candidate access networks after handoff execution. Simulation results confirm that our proposed predictive handover mechanism significantly outperforms an existing reference base station efficiency based approach.

关键词： Interference Handover Wireless LAN Throughput Long Term Evolution Logic gates

Mutual visibility by robots with persistent memory

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arXiv 2017年

作者： Bhagat, Subhash Mukhopadhyaya, Krishnendu Advanced Computing and Microelectronics Unit Indian Statistical Institute Kolkata India

This paper addresses the mutual visibility problem for a set of semi-synchronous, opaque robots occupying distinct positions in the Euclidean plane. Since robots are opaque, if three robots lie on a line, the middle robot obstructs the visions of the two other robots. The mutual visibility problem asks the robots to coordinate their movements to form a configuration, within finite time and without collision, in which no three robots are collinear. Robots are endowed with a constant bits of persistent memory. In this work, we consider the FSTATE computational model in which the persistent memory is used by the robots only to remember their previous internal states. Except from this persistent memory, robots are oblivious i.e., they do not carry forward any other information from their previous computational cycles. The paper presents a distributed algorithm to solve the mutual visibility problem for a set of semi-synchronous robots using only 1 bit of persistent memory. The proposed algorithm does not impose any other restriction on the capability of the robots and guarantees collision-free movements for the robots. Copyright © 2017, The Authors. All rights reserved.

关键词： Visibility

Fast FPGA placement using space-filling curve

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Fast FPGA placement using space-filling curve

International Conference on Field Programmable Logic and Applications

作者： P. Banerjee S. Bhattacharjee S. Sur-Kolay S. Das S.C. Nandy Advanced Computing and Microelectronics Unit Indian Statistical Institute Kolkata India

In this paper, we propose a placement method for island-style FPGAs, based on recursive bi-partitioning followed by application of space-filling curves. Experimental results of our method show 55% improvement in cost, when compared to random initial placement of the popular tool VPR. The solutions thus obtained require 44.5% fewer moves during final iterative refinement by ultra-low temperature simulated annealing, whereas the quality of solution is on the average 0.1% better. This establishes the utility of the method for fast reconfiguration of FPGA based co-processors.

关键词： Field programmable gate arrays Programmable logic arrays Switches Circuits Temperature Simulated annealing Filling Routing Phased arrays Reconfigurable logic

A distributed algorithm for D2D communication in 5G using stochastic model

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A distributed algorithm for D2D communication in 5G using st...

IEEE International Symposium on Network computing and Applications

作者： Durgesh Singh Sasthi C. Ghosh Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata India

Device to device (D2D) communication in 5G is on the spurge to compensate for the exponential increase in mobile users and their data requirements. In D2D communication, proximity users can communicate and control the links among themselves without the need of base station. This brings a real challenge to model the network to incorporate uncertainty which arises due to the mobility of users. We have developed a stochastic integer programming (SIP) based model to optimize the average network delay while keeping the packet loss below a threshold. This SIP model involves a probabilistic constraint which deals with conditional probability of link breakage in the next time instance given it was active at current time instance. By exploiting the SIP model, we have developed a greedy metric termed as connectivity factor (CF) which captures the nodes' mobility and hence takes care of link reliability which in turn controls packet loss and delay per hop. Based on CF we give a pure distributed greedy algorithm for forwarding the packets to an appropriate next hop node. Advantage of our algorithm to find an appropriate next hop node is that it requires only to compute the expectation and variance of path loss, which in turn can be computed from the distributions of mobility related parameters. Here we have used random walk mobility model for simplicity, but it can be extended to other mobility model with known relevant distributions. Through simulation we have shown that our proposed algorithm gives a significant improvement in packet loss due to mobility of nodes over the traditional received signal strength (RSS) based approach and an existing contention based forwarding (CBF) approach.

关键词： Packet loss Device-to-device communication Delays Mobile nodes

DRAMS: Double-RIS Assisted Multihop Routing Scheme for Device-to-Device Communication

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arXiv 2023年

作者： Sau, Lakshmikanta Mukherjee, Priyadarshi Ghosh, Sasthi C. The Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata700108 India

Reconfigurable intelligent surfaces (RISs) is a promising solution for enhancing the performance of multihop wireless communication networks. In this paper, we propose a double-RIS assisted multihop routing scheme for a device-to-device (D2D) communication network. Specifically, the scheme is dependent on the already deployed RISs and users in the surroundings. Besides the RISs, the emphasis of this work is to make more use of the existing intermediate users (IUs), which can act as relays. Hence, the density of RIS deployment in the surroundings can be reduced, which leads to the avoidance of resource wastage. However, we cannot solely depend on the IUs because this implies complete dependence on their availability for relaying and as a result, the aspect of reliability in terms of delay-constrained information transfer cannot be guaranteed. Moreover, the IUs are considered capable of energy harvesting and as a result, they do not waste their own energy in the process of volunteering to act as a relay for other users. Numerical results demonstrate the advantage of the proposed scheme over some existing approaches and lastly, useful insights related to the scheme design are also drawn, where we characterize the maximum acceptable delay at each hop under different set-ups. © 2023, CC BY-NC-ND.

关键词： Energy harvesting

Network-assisted D2D relay selection under the presence of dynamic obstacles

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arXiv 2019年

作者： Singh, Durgesh Ghosh, Sasthi C. Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata700108 India

—Millimeter wave (mmWave) channels in device to device (D2D) communication are susceptible to blockages in spite of using directional beams from multi-input multi-output (MIMO) antennas to compensate for high propagation loss. This motivates one to look for the presence of obstacles while forming D2D links among user equipments (UEs) which are in motion. In D2D communication, moving UEs also act as relays to forward data from one UE to another which introduces the problem of relay selection. The problem becomes more challenging when the obstacles are also in motion (dynamic obstacles) along with the moving UEs. First we have developed a probabilistic model for relay selection which considers both moving UEs and dynamic obstacles. Then we have analyzed the probability of dynamic obstacles blocking a link in 3D Euclidean space by exploiting the information from MIMO radar connected to the base station. Finally, using this information, we have developed unique strategies based on simple geometry to find the best relay which maximizes the expected data rate. Through simulations we have shown that our proposed strategy gives a significant improvement in packet loss due to mobility of nodes and dynamic obstacles in a mmWave channel over traditional approaches which do not consider dynamic obstacle’s presence. Copyright © 2019, The Authors. All rights reserved.

关键词： 5G mobile communication systems

Mobility tolerant broadcast in mobile ad hoc networks

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6th International Workshop on Distributed computing, IWDC 2004

作者： Srimani, Pradip K Sinha, Bhabani P Department of Computer Science Clemson University ClemsonSC29634–0974 United States Advanced Computing and Microelectronics Unit Indian Statistical Institute Calcutta700108 India

ISBN: (纸本)9783540240761

A new deterministic broadcast protocol for an ad hoc network is proposed in this paper which avoids re-computation of the transmission schedule, even when the topology of the network changes due to the mobility of the nodes. The basic idea is to use a successive partitioning scheme by representing the identifier of each node (an integer) in an arbitrarily chosen radix system;the protocol then computes the specific time slots in which a particular node should transmit its message. The proposed protocol is simple, easy to implement and needs lesser broadcast time than that in [BBC99]. © Springer-Verlag Berlin Heidelberg 2004.

关键词： Mobile ad hoc networks

Priority aware grouping-based multihop routing scheme for RIS-assisted wireless networks

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arXiv 2024年

作者： Sau, Lakshmikanta Mukherjee, Priyadarshi Ghosh, Sasthi C. The Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata700108 India

Reconfigurable intelligent surfaces (RISs) is a novel communication technology that has been recognized and recently presented as a candidate for beyond fifth generation wireless communication technology. In this paper, we propose a priority aware user traffic dependent grouping based multihop routing scheme for a RIS-assisted millimeter wave (mmWave) device-to-device (D2D) communication network with spatially correlated channels. Specifically, the proposed scheme exploits the priority of the users (based on their respective delay constrained applications) and the aspect of spatial correlation in the narrowly spaced reflecting elements of the RISs. In this context, we establish a multihop connection for information transfer from one of the users to its desired receiver based on the other users in the neighbourhood, their respective traffic characteristics, and the already deployed RISs in the surroundings. Moreover, we also take into account the impact of considering practical discrete phase shifts at the RIS patches instead of its ideal continuous counterpart. Furthermore, we claim as well as demonstrate that the existing classic least remaining distance (LRD)-based approach is not always the optimal solution. Finally, numerical results demonstrate the advantages of the proposed strategy and that it significantly outperforms the existing benchmark schemes in terms of system performance metrics such as data throughput, energy consumption, as well as energy efficiency. © 2024, CC BY-NC-SA.

关键词： Millimeter waves

Circle formation by asynchronous fat robots with limited visibility

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Circle formation by asynchronous fat robots with limited vis...

8th International Conference on Distributed computing and Internet Technologies, ICDCIT 2012

作者： Dutta, Ayan Gan Chaudhuri, Sruti Datta, Suparno Mukhopadhyaya, Krishnendu Computer Science and Engineering Department Heritage Institute of Technology Kolkata 700107 India Advanced Computing and Microelectronics Unit Indian Statistical Institute 203 B.T. Road Kolkata 700108 India

ISBN: (纸本)9783642280726

This paper proposes a distributed algorithm for circle formation by multiple autonomous mobile robots. The vision of each robot is limited to a maximum distance. The robots do not store past actions or records of past data. They are anonymous and cannot be distinguished by their appearances. All robots agree on a common origin and axes. Earlier works report algorithms for gathering of multiple autonomous mobile robots in limited visibility considering the robots to be dimensionless or points. This paper models a robot as a unit disc (fat robot). The algorithm presented in this paper also assures that there is no collision among the robots. The robots do not share a common clock. They execute the algorithm asynchronously. © 2012 Springer-Verlag.

关键词： Mobile robots