Capacity and delay of hybrid wireless broadband access networks

Abstract

Abstract-An optical network is too costly to act as a broadband access network. On the other hand, a pure wireless ad hoc network with n nodes and total bandwidth of W bits per second cannot provide satisfactory broadband services since the pernode throughput diminishes as the number of users goes large. In this paper, we propose a hybrid wireless network, which is an integrated wireless and optical network, as the broadband access network. Specifically, we assume a hybrid wireless network consisting of n randomly distributed normal nodes, and m regularly placed base stations connected via an optical network. A source node transmits to its destination only with the help of normal nodes, i.e., in the ad hoc mode, if the destination can be reached within L (L ≥ 1) hops from the source. Otherwise, the transmission will be carried out in the infrastructure mode, i.e., with the help of base stations. Two transmission modes share the same bandwidth of W bits/sec. We first study the throughput capacity of such a hybrid wireless network, and observe that the throughput capacity greatly depends on the maximum hop count L and the number of base stations m. We show that the throughput capacity of a hybrid wireless network can scale linearly with n only if m = Ω(n), and when we assign all the bandwidth to the infrastructure mode traffics. We then investigate the delay in hybrid wireless networks. We find that the average packet delay can be maintained as low as Θ(1) even when the per-node throughput capacity is Θ(W ).

On Capacity and Delay of Multichannel Wireless Networks With Infrastructure Support

“…The plane A is evenly partitioned into b equal-sized squares, which are called BS-cells. Similar to [10], [14], [15], we also assume that a base station is placed at the center of each BS-cell. Unlike a node, a base station is neither a data source nor a destination and it only helps forwarding data for nodes.…”

“…In this paper, we consider the interference model [2], [8], [10]- [12], [14]. When node X i transmits to node X j over a particular channel, the transmission is successfully completed by node X j if no node within the transmission range of X j transmits over the same channel.…”

“…In particular, we first obtain the bounds on the the capacity contributed by ad hoc communications in Section V. More specifically, we will derive the upper bounds on the capacity by consideration of the aforementioned four requirements and then prove the lower bounds by constructing the cells, designing routing scheme and TDMA scheme properly. Although our approach is the integration of the previous studies on SC-IS networks [14] and MC-AH networks [8], our solution is non-trivial due to the following reasons: (i) the capacity of MC-IS networks is limited by the aforementioned four conditions simultaneously while those of SC-IS networks and MC-AH networks are only limited by subsets of the four conditions; (ii) as a result, we need to redesign the cell construction, the routing scheme and the scheduling scheme based on various factors (such as H, C A and n), which are not straight-forward. Details about our proof on ad hoc communications will be given in Section V. We will next derive the capacity contributed by infrastructure communications in Section VI.…”

“…In particular, other networks such as an SC-AH network [2], an MC-AH network [8], and an SC-IS network [14] can be regarded as special cases of our MC-IS network under the following scenarios.…”

“…Specifically, as shown in [10], [14], deploying infrastructure nodes in the wireless network can significantly improve the network capacity and reduce the average delay. But, every node in such a network equipped with a single interface cannot transmit and receive at the same time.…”