Impact of TCP protocol efficiency on mobile network capacity loss

With the rapid increases in mobile Internet users, the need for mobile data services has grown tremendously over the years. Even with the deployment of advanced mobile data networks such as HSPA and LTE, many mobile operators around the world are still experiencing challenges in fulfilling the ever increasing bandwidth demands. While the obvious bottleneck is in the network infrastructure - limited number of cells and bandwidth, it is not the only bottleneck. Paradoxically, existing mobile networks may in fact be under-utilized from time to time. This seemingly contradicting observation is due to TCP's inability to utilize all the bandwidth available. This work investigates this problem by developing a stochastic model to relate the system's service response time to TCP's protocol efficiency, and to quantify the network's capacity loss due to TCP. Using real-world network parameters the model revealed that network capacity loss is surprisingly high at typical traffic loads. More interestingly, the results uncovered the inter-play between network capacity loss and protocol/channel bandwidth limits, which opens up a new dimension to the optimization of mobile cell bandwidth allocation.