Mohan Lal

Improving Quality of Service Parameters in Wireless Asynchronous Transfer Mode Network

To support network-wide handoff, new and handoff call requests will compete for connection resources in both the mobile and backbone networks. Handoff calls require a higher congestion related performance, i.e., blocking probability, relative to new calls because forced terminations of ongoing calls due to hand-off call blocking are generally more objectionable then new call blocking from the subscribers perspective. A hybrid scheme has been proposed for handover in ATM-based PCN, which combines queuing and reservation schemes. In the scheme, FIFO and measurement based priority scheme (MBPS) queuing discipline (S. Tekinay and B. Jabbari, 1992) and reserved channel scheme (RCS) (Y.C. Kim et al., 1999) is used. This scheme gives handovers higher priority than queuing or reservation schemes. When reservation is applied on both radio and backbone channels, it leads to significant improvement in quality of service (QoS) parameters. After applying proposed scheme there is a remarkable reduction in forced termination probability (FTP) at the cost of tolerable call blocking probability (CBP)

Characterization of Surface Runoff, Soil Erosion, Nutrient Loss and their Relationship for Agricultural Plots in India

The present study was carried out to explore the existence of relationship among rainfall, runoff, soil loss and nutrient losses from the agricultural plots located at Roorkee, Uttarakhand, India. The natural rainfall generated runoff and soil loss from the 12 agricultural runoff plots (with four land uses namely sugarcane, maize, black gram and fallow land and having slope 5%, 3% and 1% for each land use) were recorded during monsoon period (June 2013 to September 2013). The highest grade plot was found to yield the highest magnitude of runoff (i.e. runoff coefficient) for a given land use and soil type. The soil loss from the experimental plots of various characteristics shown that for given rainfall input, on average, the plots with sugarcane land use were found to produce high amount of soil loss followed by Maize, fallow land and Blackgram. The nutrients losses were very low in the sediment as compared to the dissolved losses. Nutrients concentrations in sediment and runoff water were found to be more during the critical period. The higher limit of seasonal sediment yield obtained from the present study is lower than soil loss tolerance limit of 2.5 to 12.5 t/ha /yr for Indian subcontinent.

A HYBRID SCHEME FOR HANDOVER IN ATM-BASED PERSONAL COMMUNICATION NETWORK

In a Personal Communication Networks (PCN), the covered geographical area is typically partitioned into a set of microcells. Each microcell has a Base Station (BS) to exchange radio signals with wireless mobile terminals. Due to the limited range of wireless transceivers, mobile users can communicate only with BSs that reside within the same microcell at any instance. The number of handoffs/handovers during a call will increase as the cell radii decrease, thus affecting the Quality of Service (QoS). Frequent handoff in wireless/mobile networks introduces a new paradigm in the area of network congestion and admission control. The increase in processing load due to demand for service and fast handoffs to mitigate the propagation effect, a high speed backbone network for the PCN to connect BS is required. The ATM technology, which has recently emerged to be a predominant switching technology, is suited to be an infrastructure to interconnect the BSs of the PCN. To support network-wide handoff, new and handoff call requests will compete for connection resources in both the mobile and backbone networks. Handoff calls require a higher congestion related performance, i.e. blocking probability, relative to new calls because forced terminations of ongoing calls due to hand-off call blocking are generally more objectionable then new call blocking from the subscribers perspective. A hybrid scheme has been proposed for handover in ATM-based PCN, which combines queuing and reservation schemes. In the scheme, FIFO and Measurement Based Priority Scheme (MBPS) queuing discipline [Tekinay & Jabbari, 1992] and the Reserved Channel Scheme (RCS) [Kim et al., 1999] are used. This scheme gives handovers higher priority than queuing or reservation schemes. When reservation is applied on both radio and backbone channels, it leads to significant improvement in QoS. After applying proposed scheme there is a remarkable reduction in Forced Termination Probability (FTP) at the cost of tolerable Call Blocking Probability (CBP).

Performance Evaluation of Fine Tuned Fuzzy Token Bucket Scheme for High Speed Networks

The dynamic nature of the bursty traffic of high speed ATM networks may cause severe network congestion. Thus, to assure QoS, policing is required as the preventive congestion control mechanism. The fuzzy token bucket scheme was proposed for predicting and policing the token generation rate for congestion control in a high speed networks. In this paper, fuzzy-token bucket scheme is compared with token bucket scheme on the basis of two parameters: Average Delay and Throughput. A simulation study was performed for the fuzzy logic predictor using MATLAB-Simulink simulator. The simulation results show that the fuzzy logic based token bucket scheme achieve high throughput and offer lower average delay as compared to the a non-fuzzy token bucket scheme.

Comparatively simulation study to control congestion for wireless ATM networks

This paper focuses on the problem of congestion control in wireless ATM network. This is a practical fact that frequent handoff in Personal Communication Network (PCN) introduces the phenomena of congestion. After studying the currently used schemes, it is clear that there is some room for improvement for conventional handoff ordering schemes. A new Hybrid Scheme [Gupta et al., 2006] proposed by the authors to solve the hand off / hand over problem in ATM-based PCN, which aims to give handover calls high priority over new calls. When reservation is applied on both radio and backbone channels, it leads to significant decrease in Forced Termination Probability (FTP) with acceptable increase in Call Blocking Probability (CBP). Since the number of resources is limited (i.e. radio channels) as more channels are assigned to serve handover request, blocking probability will increase, which is obvious. Comparative simulation study carried out to show how improvement is achieved by using the Hybrid Scheme in comparison to the other schemes like First-In-First-Out (FIFO) and Measurement Based Priority Scheme (MBPS) [Tekinay & Jabbari, 1992]. The improvement reflects remarkable reduced percentage of FTP due to handover failure, when we use our proposed Hybrid Scheme.

Capacity of M-ary CDMA cellular communication network

We know that the CDMA (code division multiple access) technique can provide efficient multiple access to a large number of users but has the disadvantage that it requires a high bandwidth. It is also known that CDMA as a multiple access method could be combined with any desired modulation technique. An interesting question is what would be the result of combining CDMA access with a high-efficiency modulation technique, e.g. 256-QAM (quadrature amplitude modulation). In this paper we consider whether the bandwidth efficiency of high-level QAM can be used to overcome the bandwidth inefficiency of CDMA. A mathematical model is built to compare cellular capacity obtained with and without MQAM-CDMA use. It is seen that in fact, MQAM-CDMA leads to reduced capacity as compared to FDMA. However, MQMA-CDMA capacity increased as compared to simple CDMA multiple access scheme. We also consider the effect of voice activity detection (VAD) and sectorisation. This work is the extension of R.R .Gezzi (1993)

Analysis and Simulation of Non-Blocking Multiple Input ATM Switches based on Input Queuing

This paper studies the bursty traffic performance on non-blocking multiple input ATM switches. The interconnection network of the ATM switch is such that each input port maintains a separate queue of cells for each output port. A cell leaves its queue after receiving services of one time slot duration. When cells are served according to first-in-first-out (FIFO) strategy, then due to head-of-line (HOL) blocking the performance of the switch is degraded. In order to improve the performance of non-blocking ATM switches, we need to deal with the HOL blocking problem. It was shown by Karol et al through mathematical analysis and computer simulation that HOL blocking limits the throughput [5] of each input port to a maximum of 58.6% under uniform random traffic and much lower than that for bursty traffic. In this paper we have used the parallel iterative matching (PIM) technique to reduce the HOL blocking as described in [6]. In this work, link bandwidth is taken as 155.5 Mbps. So minimum delay suffered by a cell is 2.827 μs. Each input VBR source i, i=1, 2………N, is modelled by two state ON-OFF Interrupted Bernoulli Process (IBP). The switch throughput and mean cell delay are computed using simulation for different switch sizes. It has been observed by simulation that PIM technique increases throughput and reduces mean cell delay. These results are more suitable for providing better quality of service for real time bursty applications.