Caching in Ubiquitous Computing Environments: Light and Shadow

of the CA is described as follows. 1. Router retrieves a new task from the task queue. If there is no task in the task queue, then ends. 2. Router generates a PE chain which is used to process a task. Set the PEs in the PE chain as busy, which means these PE can not do any other task until they are released. 3. Router sends the PE chain information and task to PE1. 4. PE1 finishes its work and follows the PE chain information to transfer the task to PE2. 5. PE2 finishes its work and follows the PE chain information to transfer the task to PE3. 6. PE4 finishes its work and follows the PE chain information to transfer the task to PE5. 7. PE5 finishes its work and follows the PE chain information to transfer the task to PE6. 8. PE6 finishes its work and sends the processed task back to router. 9. Router sets all PEs in the PE chain as idle. 10. Remove the task from the task queue. If there is no task left in the task queue, then terminates. Otherwise go to Step (1). 4.2 Randomly Allocating Algorithm (RAA) The biggest limitation of the current policy is that if the RR allocates the PEs to the users once, the all PEs are reserved until the whole task will be finished. This is obviously a big useless of the computational resource. To regard as this point, we apply a randomly distribute algorithm to the UMP system. The concept of RAA is after the PE finished the