Akkihebbal L. Ananda

Indriya: A Low-Cost, 3D Wireless Sensor Network Testbed

This paper presents Indriya, a large-scale, low-cost wireless sensor network testbed deployed at the National University of Singapore. Indriya uses TelosB devices and it is built on an active-USB infrastructure. The infrastructure acts as a remote programming back-channel and it also supplies electric power to sensor devices. Indriya is designed to reduce the costs of both deployment and maintenance of a large-scale testbed. Indriya has been in use by over 100 users with its maintenance incurring less than US

A survey of remote procedure calls

500 for almost 2 years of its usage.

A survey of asynchronous remote procedure calls

The Remote Procedure Call (RPC) is a popular paradigm for inter-process communication (IPC) between processes in different computers across the network. It is widely used in various Distributed Systems. Although it is conceptually simple and straightforward to implement, there are a lot of different and subtle issues involved which result different RPC implementations. In this paper, various distinctive RPC implementations are surveyed, analyzed and compared: Xerox Courier RPC, Xerox Cedar RPC, Sun ONC/RPC, Apollo NCA/RPC, Cambridge Mayflower Project RPC, MIT Athena Project RPC, Stanford Modula/V RPC, and Rajdoot RPC are presented. The design objectives, features provided, call semantics, orphan treatment, binding, transport protocols supported, security/authentication, data representation and application programming interface of these RPCs are examined.

Using mobile phone barometer for low-power transportation context detection

Remote Procedure Call (RPC) is a popular paradigm for interprocess communication in distributed systems. It is simple, flexible and powerful. However, most of the RPC systems today are synchronous in nature, and hence fail to exploit fully the parallelism inherent in distributed applications. In view of this, various asynchronous RPC systems have been designed and implemented to achieve higher parallelism while retaining the familiarity and simplicity of synchronous RPC. Asynchronous RPC calls do not block the caller (client) and the replies can be received as and when they are needed, thus allowing the client execution to proceed locally in parallel with the callee (server) invocation. Asynchronous RPC calls can be classified into two types depending on whether the calls return a value. Most asynchronous RPC systems only support calls that do not return a value, and few support both classes. In this paper, an analysis and comparison of various asynchronous RPC systems are presented.

Link characteristics estimation for IEEE 802.11 DCF based WLAN

Accelerometer is the predominant sensor used for low-power context detection on smartphones. Although low-power, accelerometer is orientation and position-dependent, requires a high sampling rate, and subsequently complex processing and training to achieve good accuracy. We present an alternative approach for context detection using only the smartphones barometer, a relatively new sensor now present in an increasing number of devices. The barometer is independent of phone position and orientation. Using a low sampling rate of 1 Hz, and simple processing based on intuitive logic, we demonstrate that it is possible to use the barometer for detecting the basic user activities of IDLE, WALKING, and VEHICLE at extremely low-power. We evaluate our approach using 47 hours of real-world transportation traces from 3 countries and 13 individuals, as well as more than 900 km of elevation data pulled from Google Maps from 5 cities, comparing power and accuracy to Googles accelerometer-based Activity Recognition algorithm, and to Future Urban Mobility Surveys (FMS) GPS-accelerometer server-based application. Our barometer-based approach uses 32 mW lower power compared to Google, and has comparable accuracy to both Google and FMS. This is the first paper that uses only the barometer for context detection.

A QoS enabled MAC protocol for multi-hop ad hoc wireless networks

Knowledge of network path characteristics enables upper layers to improve performance through adaptation protocols which adjust behaviors according to current network path characteristics. For a mobile node of a wireless network, this knowledge is especially valuable because the characteristics of the wireless link, which often dominate network path characteristics, change frequently and abruptly due to mobility, fading, and contention among nodes. Due to the dynamics and precious bandwidth of the wireless link, the commonly used probing packet methods are not appropriate for estimating the characteristics of a network path with a wireless link. We propose a new mechanism to estimate link characteristics of IEEE 802.11 DCF (distributed coordination function) based wireless LAN (WLAN), one of the most popular wireless access networks. Instead of sending probing-packets, a mobile node estimates its link characteristics based on wireless link quality and the contention status of the whole WLAN. We implement this mechanism and test its accuracy in NS2.

ASTRA-an asynchronous remote procedure call facility

A medium access control (MAC) technique for multi-hop wireless networks with quality of service (QoS) assurance is introduced The proposed protocol deals with most of the hidden node problems in a multi-hop environment and also provides service differentiation for various types of traffic: real-time constant bit rate (CBR) traffic, real-time variable bit rate (VBR) traffic, and non-real-time datagram traffic, by guaranteeing bounded delay for real-time traffic, at the same time avoiding lockout of datagram traffic. It uses a distributed mechanism of scheduling and reserving the channel access for real-time sessions. Transmission of datagram or starting packet of a new realtime session is granted only after checking the reservation such that they do not affect the scheduled ongoing real-time sessions. The protocol has been implemented and tested using the VINT Network Simulator 2 (NS2). The performance evaluation and comparison confirm the improved QoS features and multimedia support compared to various existing QoS enabled MAC protocols.

Client-server based ray-tracer using ASTRA: an asynchronous RPC mechanism

A transport-independent asynchronous RPC (remote procedure call) mechanism (ASTRA) that combines the advantages of both RPC and message-passing IPC (interprocess communication) has been designed and implemented. ASTRA calls do not block the caller (client) and the replies can be received as and when they are needed, thus allowing the client execution to proceed locally in parallel with the server invocation. All the calls are received and executed by the server in the order called by the client. ASTRA is unique among other asynchronous RPC systems in allowing its users to explicitly specify whether low-latency or high-throughput is required for a call, and in providing highly optimized lightweight intramachine calls. ASTRA is built within the framework of the SHILPA distributed computing environment.<<ETX>>

Game action based power management for multiplayer online game

Abstract A distributed ray tracer is implemented in a network of workstations using ASTRA, an asynchronous remote procedure call mechanism. The motivation of this work is to utilize the idle cycles available on workstations to speed up the execution of the ray tracing task. The application uses the client-server model with a central dispatcher as the client, sending ray tracing jobs to the servers which handle the actual ray tracing computations. A new job is given to a server that has completed its present job and successfully sent back the results. Performance tests are conducted on a group of homogeneous and heterogeneous workstations using different scene complexities and varying number of servers. Our results showed that for some of the databases, it is possible to achieve 64 times speedup with 85 servers. The paper discusses the ASTRA call primitives, the client and server parts of our distributed ray tracer program, and presents the results of the performance tests.

SCTP vs TCP : performance comparison in MANETs

Current mobile devices embrace a wide range of functionalities including high speed network support, hardware accelerated 3D graphics, and multimedia capabilities. These capabilities have boosted the interest for enabling multiplayer online games (MOG) support on such devices. However, the lack of similar growth in battery technology limits the usability of these devices for MOGs. In this paper, we present energy conservation techniques for highly interactive MOGs. These are games, such as first-person shooters, where crisp user interaction is paramount to the overall game experience. Hence, conserving energy while preserving crisp user interaction becomes a critical consideration in this domain. We first present three obvious power management approaches and highlight their limitations. We then discuss two application-assisted approaches for power management that manage to save power while preserving the required user experience. Our results demonstrate that these application-assisted approaches are very promising.