Malati Hegde

Nonintrusive TCP connection admission control for bandwidth management of an Internet access link

We describe our approach to monitoring and managing the bandwidth of an Internet edge link with a view toward certain quality of service objectives for the services it carries. Such a link could be, for example, a campuss Internet access link or a small ISPs backbone access link. We use SNMP polls and packet snooping to obtain traffic statistics, and TCP admission control for bandwidth management. Our implementation is completely nonintrusive: we use Ethernet packet capture in the promiscuous mode for traffic analysis, and IP masquerading for blocking new TCP connections. This approach has been implemented by us in a software system for traffic management. We first justify our approach with a simple analytical model. We give an overview of our software implementation, and discuss some implementation issues. Then we provide measurement results that show the effectiveness of the techniques.

Phenology and seasonality in the tropical deciduous forest of Bandipur, South India

A long term study on the phenology of tree species of tropical dry deciduous forest ecosystem of Bandipur, South India has revealed patterns of strong seasonality with respect to leaf and fruit initiation as well as their abscission. The distribution of the duration of the various phenological events was observed to be skewed and there was little interannual variation in events such as flowering and fruiting. This suggests that there are, perhaps, no mast flowering or fruiting species present in the deciduous forests. The phenological changes appear to influence the food, feeding, movement patterns and sociality of the major mammals of this dry deciduous ecosystem.

Birds of the man-made ecosystems: the plantations

One-hectare plots were sampled for bird species diversity in the Uttara Kannada district. These plots represented well-preserved evergreen/semievergreen forests, secondary/moist deciduous forests showing different levels of degradation by man and plantations of teak, eucalypts and betelnut. It was found that the betelnut plantation and the evergreen/semievergreen forests had the least bird species diversity ofH′ = 2.58 and 2.61 respectively. The eucalypt and teak plantations hadH′ = 2.69 and 2-92 respectively. In the secondary/moist deciduous forests it ranged from 2.80–3.39. Despite the apparent increase in diversity in the man-modified vegetation types, it was found that there was a gradual displacement of the bird species composition from what was typical to the evergreen forests to those of more urban and scrubby habitats in these man-modified vegetation types. This was particularly so in the eucalypt plantation.

Experiences with a centralized scheduling approach for performance management of IEEE 802.11 wireless LANs

We present a centralized integrated approach for: 1) enhancing the performance of an IEEE 802.11 infrastructure wireless local area network (WLAN), and 2) managing the access link that connects the WLAN to the Internet. Our approach, which is implemented on a standard Linux platform, and which we call ADvanced Wi-fi Internet Service EnhanceR (ADWISER), is an extension of our previous system WLAN Manager (WM). ADWISER addresses several infrastructure WLAN performance anomalies such as mixed-rate inefficiency, unfair medium sharing between simultaneous TCP uploads and downloads, and inefficient utilization of the Internet access bandwidth when Internet transfers compete with LAN-WLAN transfers, etc. The approach is via centralized queueing and scheduling, using a novel, configurable, cascaded packet queueing and scheduling architecture, with an adaptive service rate. In this paper, we describe the design of ADWISER and report results of extensive experimentation conducted on a hybrid testbed consisting of real end-systems and an emulated WLAN on Qualnet. We also present results from a physical testbed consisting of one access point (AP) and a few end-systems.

A low-complexity algorithm for intrusion detection in a PIR-based Wireless Sensor Network

We present a low-complexity algorithm for intrusion detection in the presence of clutter arising from wind-blown vegetation, using Passive Infra-Red (PIR) sensors in a Wireless Sensor Network (WSN). The algorithm is based on a combination of Haar Transform (HT) and Support-Vector-Machine (SVM) based training and was field tested in a network setting comprising of 15–20 sensing nodes. Also contained in this paper is a closed-form expression for the signal generated by an intruder moving at a constant velocity. It is shown how this expression can be exploited to determine the direction of motion information and the velocity of the intruder from the signals of three well-positioned sensors.

WLAN manager (WM): a device for performance management of a WLAN

We propose a Split MAC architecture-based solution to enhance the Quality of Service (QoS) experienced by the wireless nodes in an IEEE 802.11b/e-based WLAN. Our proposed solution achieves the objectives of (a) providing a fair sharing of the wireless channel time among stations (STAs) while maximizing channel utilization in a situation where STAs are associated at different data rates with the access point (AP), (b) exercising Connection Admission Control (CAC) for two-way voice calls, (c) supporting policy-based service differentiation among the flows within one IEEE 802.11e access category, and (d) maintaining performance levels during inter-AP roaming of STAs. The proposed solution is implemented on an extraneous device, called WM (WLAN Manager), which in CAPWAP parlance can be termed an access controller. We report simulation and test-bed results.

CyPhyS+: A Reliable and Managed Cyber-Physical System for Old-Age Home Healthcare over a 6LoWPAN Using Wearable Motes

We present design and implementation of CyPhyS+, a comprehensive, low-cost and standard complaint Cyber Physical System for remote health monitoring of elderly staying in old age homes. It is an end-to-end 6LoWPAN based healthcare system, which provides reliable and secured medical data acquisition, on the fly medical data analytics and visualization in real-time. It is designed for low power operations and resource constraint environment. The paper describes system architecture, design and implementation details of software and hardware sub-systems. As part of the system we developed power efficient Bluetooth-6LoWPAN mote, Health Mote. The paper describes novel energy efficient end-to-end multi-stage message reliability scheme. The experimental results prsented show the efficacy of the approach. For ensuring robust operational network, CyPhyS+ employs a low power and application aware SNMP based network monitoring for 6LoWPAN multihop network. In addition, CyPhyS+ incorporates a 128-bit AES, CBC-MAC based encryption and authentication mechanism. Other notable features of CyPhyS+ include its compliance with open FHIR/HL7 medical standards, support for Restful architecture based web services, and medical data analytics of ECG. We report on the extensive field trials that have been carried out across various parts of the city.

SeaMo+: A virtual real-time multimedia service framework on handhelds to enable remote real-time patient monitoring for mobile doctors

The key requirements for enabling real-time remote healthcare service on a mobile platform, in the present day heterogeneous wireless access network environment, are uninterrupted and continuous access to the online patient vital medical data, monitor the physical condition of the patient through video streaming, and so on. For an application, this continuity has to be sufficiently transparent both from a performance perspective as well as a Quality of Experience (QoE) perspective. While mobility protocols (MIPv6, HIP, SCTP, DSMIP, PMIP, and SIP) strive to provide both and do so, limited or non-availability (deployment) of these protocols on provider networks and server side infrastructure has impeded adoption of mobility on end user platforms. Add to this, the cumbersome OS configuration procedures required to enable mobility protocol support on end user devices and the users enthusiasm to add this support is lost. Considering the lack of proper mobility implementations that meet the remote healthcare requirements above, we propose SeaMo+ that comprises a light-weight application layer framework, termed as the Virtual Real-time Multimedia Service (VRMS) for mobile devices to provide an uninterrupted realtime multimedia information access to the mobile user. VRMS is easy to configure, platform independent, and does not require additional network infrastructure unlike other existing schemes. We illustrate the working of SeaMo+ in two realistic remote patient monitoring application scenarios.

6PANview: Application performance conscious network monitoring for 6LoWPAN based WSNs

6PANview[1] is a Wireless Sensor Network(WSN) monitoring system for 6LoWPAN/RPL networks which we developed as an overlay network for a WSN application. A monitoring system, while performing its operations for maintaining the health of the monitored network, must also be conscious of its impact on the application performance, and must strive to minimize this impact. To this end, we propose a centralized scheduling algorithm within 6PANview which non-intrusively analyzes application traffic arrival patterns at the base station, identifies network idle periods and schedules monitoring activities. The proposed algorithm finds those periodic sequences which are likely to have given rise to the pattern of arrivals seen at the base station. Parts of those sequences are then extended to coarsely predict future traffic and find epochs where low traffic is predicted, in order to schedule monitoring traffic or other activities at these times. We present simulation results for the proposed prediction and scheduling algorithm and its implementation as part of 6PANview. As an enhancement, we briefly talk about using 6PANviews overlay network architecture for distributed scheduling.

A Vertical Handoff decision scheme for end-to-end QoS in heterogeneous networks: An implementation on a mobile IP testbed

A prominent function of a mobile host is seamless Vertical Handoff (VHO) that ensures application service continuity and quality. VHO decision algorithms that have been proposed in the literature consider parameters such as wireless channel quality (RSSI), cost, channel load, and available bandwidth. The mobile node runs the VHO algorithm autonomously and makes the decision. We highlight the fact that such a local decision can potentially result in a poor end-to-end application level QoS. We present a VHO scheme that takes into account end-to-end QoS as one of the key parameters in addition to other common parameters. We propose an architecture involving an external host based light-weight server (Access Link Utilization Monitor) that disseminates the available end-to-end bandwidth to the mobile node to assist it in making a decision to maintain end-to-end service quality. We describe a fuzzy logic based algorithm that has been used in the handoff decision. We present the results of our implementation on a mobile IP testbed under different realistic scenarios, that include WLAN, WiMAX and 3G access technologies to demonstrate the efficacy of the proposed scheme.