Grid computing serves as an important technology to facilitate distributed computation computational grids solve large scale scientific problems using heterogeneous geographically distributed resources. Problems like dispatching and scheduling of tasks are considered as major issues in computational grid environment. The Grid Scheduler must select proper resources for executing the tasks with less response time. There are various reasons such as network failure, overloaded resource conditions, or non-availability of required software components for execution failure. Thus, fault-tolerant systems should be able to identify and handle failures and support reliable execution in the presence of failures. Hence the integration of fault tolerance measures and communication time with scheduling gains much importance. In this study, a new fault tolerance based scheduling approach Fault Tolerant Min-Min (FTMM) for scheduling statically available meta tasks is proposed wherein failure rate and the fitness value are calculated. The performance of the fault tolerant scheduling policy is compared with min-min scheduling policy using GridSim and the results shows that the proposed policy performs better with less makespan in the presence of failures. The number of tasks successfully completed is also more when compared to the non-fault tolerant min-min scheduling policy. Thus the proposed FTMM algorithm not only achieves better hit rate but also improved makespan

Problem statement:This study proposes a novel Distributed Amplify and-Forward (DAF) cooperative scheme, achieving higher diversity order and yet maintaining the same transmission freedom as the conventional Amplify-and-Forward (AF) scheme. In the DAF scheme, a user's transmitted symbols are partitioned into several sequences in order to be relayed by different users. Approach: In the cooperative network, each user still uses half of their transmission for relaying others' signals. But instead of relaying one user's entire transmitted sequence, it helps different users for the relaying. Theoretical analysis of the DAF scheme is carried out in order to justify its advantages over the existing schemes. The outage behavior and Diversity-Multiplexing Tradeoff (DMT) analyses of the DAF scheme are presented. Results: Through outage behavior analysis, it is shown the DAF scheme achieves substantial diversity gains over the AF scheme. Furthermore, the DMT analysis justices both the scheme's achievable diversity gains and its ability to maintain the same multiplexing gain as the AF scheme. The theoretical analyses are then extended to a general cooperative network consisting of N (N≥2) relays, showing the diversity order can be increased with respect to the number of relays but not at the expense of each user's multiplexing gain. Conclusion: Finally, a practical coded cooperative system that integrates the DAF scheme with the concatenated Reed-Solomon Convolution Codes (RSCC) is proposed, validating the achievable performance gain offered by the DAF scheme.