Scalability in Mobile Device Networks

The overall end user synchronization experience in a mobile device is determined by a variety of factors including latency in synchronization, the amount of battery power used, any monetary cost involved (such as the cost of the network connection, air time etc.) and the robustness and reliability of the synchronization routine. The overall scalability of any synchronization protocol is determined by how well the protocol addresses these issues.

Figure 2.2: Pentagon of Scalability in Mobile Device Networks

PDAs and other mobile devices are limited in how fast they can communicate over a network because of the nature of the links that connect them. Moreover, their limited computational capabilities are a significant factor in the design of a synchronization protocol for these devices. They have additional constraints of limited memories and limited power supplies (see Figure 1.1). Figure 2.2 shows the overall issues when mobile device synchronization is considered, with each of the vertices of the pentagon representing a scalability issue in mobile device synchronization. The computation and communication have a direct bearing on the latency and the battery usage of the device. Mobile device memories are limited and any protocol which uses a lot of memory will not be suitable for many of the lower end devices. At the same time, we wish to develop protocols that allow a large number of devices on the network to synchronize among themselves and are robust and preferably peer-to-peer instead of centralized, keeping in line with the ad-hoc nature of mobile device networks.

Figure 2.3: Comparison between the communication complexities (in bytes) of Fastsync and Slowsync.