Network Assisted Mobile Computing with Optimal Uplink Query Processing(2012)

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Many mobile applications retrieve content from remote servers via user generated queries. Processing these queries is often needed before the desired content can be identified. Processing the request on the mobile devices can quickly sap the limited battery resources. Conversely, processing user-queries at remote servers can have slow response times due communication latency incurred during transmission of the potentially large query. We evaluate a network-assisted mobile computing scenario where midnetwork nodes with “leasing” capabilities are deployed by a service provider. Leasing computation power can reduce battery usage on the mobile devices and improve response times. However, borrowing processing power from mid-network nodes comes at a leasing cost which must be accounted for when making the decision of where processing should occur. We study the tradeoff between battery usage, processing and transmission latency, and mid-network leasing. We use the dynamic programming framework to solve for the optimal processing policies that suggest the amount of processing to be done at each mid-network node in order to minimize the processing and communication latency and processing costs. Through numerical studies, we examine the properties of the optimal processing policy and the core tradeoffs in such systems.

Existing System:

In the previous section we identified special properties of the optimal processing policy under various scenarios. We now examine some of these properties through numerical studies with example cost functions and systems. Latency, battery usage, and leasing costs have a tightly woven relationship.


i.      Increasing battery usage will decrease latency and leasing costs, but also limits the lifetime of the mobile device.

ii.      Conversely, the lifetime of the device can be extended by increasing leasing costs which will decrease latency and battery usage.

Proposed System:

A user request originates at the Mobile Station (MS). In order to be completed, the request must be transmitted upstream to a remote Application Server (AS) via a Base Station (BS) and a series of relay nodes. We refer to the node at the first hop as the base station, but emphasize that the links between the BS, relay nodes, and AS may be wired or wireless. Similarly running a text to speech conversion application for usage scenarios.


i.      If the request processing is entirely done at the MS, the limited battery power can be drained.

ii.      If the processing is done at the AS, communication latency can be high due to limited bandwidth of the wireless access link and large query size.


1.     Leasing Model

2.     Relaying Strategies

3.     Multi-hop Transmission

Leasing Model:

Utilizing the processing power of intermediary nodes is the main idea behind Network-Assisted Mobile Computing. Leasing processing power from mid-network nodes can be extremely beneficial to reduce latency and to extend the battery life of a mobile device. However, it comes with a cost. These costs can capture the fee required to lease CPU power from the mid-network nodes. Additionally, these costs may capture potential security risks by giving access of client data to these nodes. Some operations, such as transcoding, can be done on

Encrypted data, while other would require decrypting the data. The mobile station send one sentence for ex: (how are you), in the application server receive the sentence into audio.

Relaying Strategies:

• Amplify-and-forward

 • Decode-and-forward

In amplify-and-forward, the relay nodes simply boost the energy of the signal received from the sender and retransmit it to the receiver. In decode-and-forward, the relay nodes will perform physical-layer decoding and then forward the decoding result to the destinations. If multiple nodes are available for cooperation, their antennas can employ a space-time code in transmitting the relay signals. It is shown that cooperation at the physical layer can achieve full levels of diversity similar to a system, and hence can reduce the interference and increase the connectivity of wireless networks.

Multi-hop Transmission:

Multi-hop transmission can be illustrated using two-hop transmission. When two-hop transmission is used, two time slots are consumed. In the first slot, messages are transmitted from the mobile station to the relay, and the messages will be forwarded to the Application Server in the second slot. The outage capacity of this two-hop transmission can be derived considering the outage of each hop transmission.



·                     System                 :         Pentium IV 2.4 GHz.

·                     Hard Disk            :         40 GB.

·                     Floppy Drive       :         1.44 Mb.

·                     Monitor                :         15 VGA Color.

·                     Mouse                  :         Logitech.

·                     Ram                     :         512 MB.


·                     Operating system           :         Windows XP Professional.

·                     Coding Language  :         C#.NET

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