Multipath TCP (MP-TCP) has the potential to greatly improve application performance by using multiple paths transparently. We propose a fluid model for a large class of MP-TCP algorithms and identify design criteria that guarantee the existence, uniqueness, and stability of system equilibrium. We clarify how algorithm parameters impact TCP-friendliness, responsiveness, and window oscillation and demonstrate an inevitable tradeoff among these properties. We discuss the implications of these properties on the behavior of existing algorithms and motivate our algorithm Balia (balanced linked adaptation), which generalizes existing algorithms and strikes a good balance among TCP-friendliness, responsiveness, and window oscillation. We have implemented Balia in the Linux kernel. We use our prototype to compare the new algorithm to existing MP-TCP algorithms.

Most mobile devices today come with multiple access interfaces, \emph{e.g.}, 4G and WiFi. Multipath TCP (MP-TCP) can greatly improve network performance by exploiting the connection diversity of multiple access interfaces, at the expense of higher energy consumption. In this paper, we design MP-TCP algorithms for mobile devices by jointly considering the performance and energy consumption. We consider two main types of mobile applications: realtime applications that have a fixed duration and file transfer applications that have a fixed data size. For each type of applications, we propose a two-timescale algorithm with theoretical guarantee on the performance. We present simulation results that show that our algorithms can reduce energy consumption by up to 22$\%$ without sacrificing throughput compared to a baseline MP-TCP algorithm.

In this paper, we investigate the multicast capacity for static ad hoc networks with heterogeneous clusters. We study the effect of heterogeneous cluster traffic (HCT) on the achievable capacity. HCT means cluster clients are more likely to appear near the cluster head instead of being uniformly distributed across the network. Such a property is commonly found in real networks. By adopting max-min fairness, the minimum among all individual multicast capacities of clusters can be maximized. Since this minimal individual multicast capacity will not be maximized unlimitedly, our work focuses on deriving the upper bound of the minimum individual multicast capacity (we refer it as minimum capacity for simplicity) in HCT, which provides the best performance for the minimum multicast capacity to attain in the whole network. We find that HCT increases minimum capacity for ad hoc networks. Furthermore, the multicast capacity achieving scheme is provided to justify the derived asymptotic upper bound for the minimum capacity. Our work can generalize various results obtained under nonheterogeneous networks in previous literature.

Multi-path TCP (MP-TCP) has the potential to greatly improve application performance by using multiple paths transparently. We propose a fluid model for a large class of MP-TCP algorithms and identify design criteria that guarantee the existence, uniqueness, and stability of system equilibrium. We characterize algorithm parameters for TCP-friendliness and prove an inevitable tradeoff between responsiveness and friendliness. We discuss the implications of these properties on the behavior of existing algorithms and motivate a new design that generalizes existing algorithms. We use ns2 simulations to evaluate the proposed algorithm and illustrate its superior overall performance.

In this paper, we focus on capacity-delay tradeoffs for multicast traffic pattern. Under the assumption that n nodes move in a unit square according to an i.i.d. mobility model, with each serving as a source that sends identical packets to k destinations, we propose four schemes of which the achievable capacity λ and delay D are analyzed: (1) 2-hop noncooperative non-redundancy scheme, (2) 2-hop noncooperative redundancy scheme, (3) 2-hop cooperative non-redundancy scheme, (4) 2-hop cooperative redundancy scheme. Compared with non-cooperative scheme with capacity delay tradeoff λ = O( E[D]/nk log k) first developed in [5], cooperation among destination nodes achieves optimal capacity delay tradeoff λ = O(E[D]/n log k) in cell partitioned network. With intelligent cooperation, each destination acts equivalently as relay and helps other destinations get more opportunities of receiving packets with capacity sacrificed to a addition, our redundancy schemes also allow delay under Θ(√n) log k factor compared with unicast in [3] under the same delay. In achievable, which is the minimum delay under the schemes of [3],[5].

In this paper, we define an ad hoc network where multiple sources transmit packets to one destination as Converge-Cast network. We will study the capacity delay tradeoffs assuming that n wireless nodes are deployed in a unit square. For each session (the session is a dataflow from k different source nodes to 1 destination node), k nodes are randomly selected as active sources and each transmits one packet to a particular destination node, which is also randomly selected. We first consider the stationary case, where capacity is mainly discussed and delay is entirely dependent on the average number of hops. We find that the per-node capacity is Θ (1/√(n log n)) (given nonnegative functions f(n) and g(n): f(n) = O(g(n)) means there exist positive constants c and m such that f(n) ≤ cg(n) for all n ≥ m; f(n)= Ω (g(n)) means there exist positive constants c and m such that f(n) ≥ cg(n) for all n ≥ m; f(n) = Θ (g(n)) means that both f(n) = Ω (g(n)) and f(n) = O(g(n)) hold), which is the same as that of unicast, presented in (Gupta and Kumar, 2000). Then, node mobility is introduced to increase network capacity, for which our study is performed in two steps. The first step is to establish the delay in single-session transmission. We find that the delay is Θ (n log k) under 1-hop strategy, and Θ (n log k/m) under 2-hop redundant strategy, where m denotes the number of replicas for each packet. The second step is to find delay and capacity in multisession transmission. We reveal that the per-node capacity and delay for 2-hop nonredundancy strategy are Θ (1) and Θ (n log k), respectively. The optimal delay is Θ (√(n log k)+k) with redundancy, corresponding to a capacity of Θ (√((1/n log k) + (k/n log k)). Therefore, we obtain that the capacity delay tradeoff satisfies delay/rate ≥ Θ (n log k) for both strategies.

In this paper, we investigate the multicast capacity for static network with heterogeneous clusters. We study the effect of heterogeneities on the achievable capacity from two aspects, including heterogeneous cluster traffic (HCT) and heterogeneous cluster size (HCS). HCT means cluster clients are more likely to appear near the cluster head, instead of being uniformly distributed across the network and HCS means each cluster is also not equal in size as most prior literatures assume. Both of these two properties are commonly found in realistic networks. For this class of networks, we find that HCT increases network capacity for all the clusters and HCS does not influence the network capacity. Our work can generalize various results obtained under non-heterogeneous networks in the literature.

In this paper, we study a unified mobility model for mobile multicast (MotionCast) with n nodes, and k destinations for each multicast session. This model considers nodes which can either serve in a local region or move around globally, with a restricted speed R. In other words, there are two particular forms: Local-based Speed-Restricted Model (LSRM) and Global-based Speed-Restricted Model (GSRM). We find that there is a special turning point when mobility speed varies from zero to the scale of network. For LSRM, as R increases, the delay-capacity trade-off ratio decreases iff R is greater than the turning point θ(√1/k); For GSRM, as R increases, the trade-off ratio decreases R R is smaller than the turning point, where the turning point is located at Θ(k√nn25) when k = o(n2/3), and at θ(k/n) when k = ω(n2/3). As k increases from 1 ton -1, the region that mobility can improve delay-capacity trade-off is enlarged. When R = θ(1), the optimal delay-capacity trade-off ratio is achieved. This paper presents a general approach to study the performance of wireless networks under more flexible mobility models.