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✦ ABSTRACTThis article defines the QoS-guaranteed efficient cloudlet deploy problem in wireless metropolitan area network, which aims to minimize the average access delay of mobile users i.e. the average delay when service requests are successfully sent and being served by cloudlets. Meanwhile, we try to optimize total deploy cost represented by the total number of deployed cloudlets. For the first target, both un-designated capacity and constrained capacity cases are studied, and we have designed efficient heuristic and clustering algorithms respectively. We show our algorithms are more efficient than the existing algorithm. For the second target, we formulate an integer linear programming to minimize the number of used cloudlets with given average access delay requirment. A clustering algorithm is devised to guarantee the scalability. For a special case of the deploy cost optimization problem where all cloudlets' computing capabilities have been given, i.e., designated capacity, a minimal cloudlets efficient heuristic algorithm is further proposed.We finally evaluate the performance of proposed algorithms through extensive experimental simulations.Simulation results demonstrate the proposed algorithms are more than 46% efficient than existing algorithms on the average cloudlet access delay. Compared with existing algorithms, our proposed clustering and heuristic algorithms can reduce the number of deployed cloudlets by about 50% averagely. INTRODUCTIONWith the emerging of cloud computing and wireless communication technologies, mobile devices have become proliferation in people's daily life. Due to the small size nature of mobile devices, their computation resources are limited [1]. To improve user experience and enhance battery life, mobile applications can be offloaded to a remote cloud through wireless links [2]. However, the cloud is usually far away from users, which results in a high end-to-end latency [3]. To meet the delay requirment of mobile applications, cloudlets are proposed to extend the traditional mobile device-cloud architecture [4]. The cloudlet is a trusted, computation rich device that is deployed at the access point (AP) or base station [1], available to be used by nearby mobile devices. For the mobile device, access proximity to the cloudlet is very important to reduce end-to-end delay. So the best location for the cloudlet is one wireless hop away from the mobile device.Although there have been extensive studies on resource allocation in cloudlet based networks, there are only a few works focusing on cloudlet deployment. Meanwhile, how to guarantee the quality of service (QoS) of cloudlet based wireless metropolitan area network (WMAN) is somehow overlooked. In hot spot areas [5], cloudlet servers can always be accessed by a large number of mobile users whereas it will not be the case in sparsely populated areas and the cloudlets' resources may be wasted. If we allocate the cloudlet resources based on the number of user requests, the cloudlet utilization efficiency could be improved. Due ...

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