We analyze a massive social network, gathered from the records of a large mobile phone operator, with more than a million users and tens of millions of calls. We examine the distributions of the number of phone calls per customer; the total talk minutes per customer; and the distinct number of calling partners per customer. We find that these distributions are skewed, and that they significantly deviate from what would be expected by power-law and lognormal distributions.

We present an experimental characterization of the physical and MAC layers in CDMA 1xEV-DO and their impact on transport layer performance. The 1xEV-DO network is currently the fastest mobile broadband cellular network, offering data rates of up to 3.1 Mbps for both stationary and mobile users. These rates are achieved by using novel capacity enhancement techniques at the lower layers. Specifically, 1xEV-DO incorporates rapid channel rate adaptation in response to signal conditions, and opportunistic scheduling to exploit channel fluctuations. Although shown to perform well in isolation, there is no comprehensive literature that examines the impact of these features on transport layer and application performance in real networks.

We study how a server may disseminate a large volume of data to a set of clients in the shortest possible time. Cooperative scenarios where clients are willing to upload data to each other and, under a simple bandwidth model, derive an optimal solution involving communication on a hypercube-like overlay network were first considered. The authors also studied different randomized algorithms, and show that their performance is surprisingly good. Then non-cooperative scenarios based on the principle of barter, in which one client does not upload to another unless it receives data in return were considered. A strict barter requirement increases the optimal completion time considerably compared to the cooperative case. Relaxations of the barter model in which an efficient solution is theoretically feasible was also considered, and show that obtaining a high-performance practical solution may require careful choices of overlay networks and data-transfer algorithms

Researchers and commercial developers have proposed several protocols to enable efficient multi-point communication both at the IP layer and at the application or overlay layer. However, no single protocol has made enough headway in terms of deployment for it to span the entire Internet. In fact, we believe that none of the existing multicast or broadcast protocols will become the sole dominant Internet broadcasting technology any time in the near future. Instead, we expect islands of non-interoperable broadcast connectivity. To address this, we propose an architecture that enables the composition of different broadcast protocol, to provide an end-to-end broadcast service. We call this architecture the Broadcast Federation. In this paper, we describe the architecture along with a prototype implementation and preliminary results from the prototype.