Cooperative Communication

Introduction The classic representation of a communication network is a graph, as in Figure 1.1, with a set of nodes and edges. The nodes usually represent devices such as a router, a wireless access point, or a mobile telephone. The edges usually represent communication links or channels, for example a fiber-optic cable or a wireless […]

Network Layering (Conventional Networks)

Before describing cooperative protocols and networks, we start with a review of networking models and common practices. Our discussion introduces the conventional decomposition of a network into protocol layers. We then employ these layers to organize the subsequent review of the physical, link, and network layer protocols. We recognize that future cooperative networks will also […]

Physical Layer: Communication Theory (Conventional Networks)

We review basic concepts of communication theory. This theory is useful for all network layers, but in particular for the PHY and application layers where source and/or channel coding are used. The following sections also introduce notation that we use throughout the document. Information Theory Information theory began as the mathematics of communications for one […]

Link Layer: ARQ and HARQ Protocols (Conventional Networks)

For the PHY layer, error control is usually based on both Automatic Retransmission ReQuest (ARQ) and FEC schemes ("forward" refers to the non-feedback aspect of error control where a code automatically corrects errors detected at the receiver). ARQ is a link layer protocol that provides reliability based on error-detecting codes and retransmissions. A parity-bit or […]

Network Layer: Wireless Routing Protocols (Conventional Networks)

The role of the network layer is to route packets to their intended destinations. In a traditional network, a node implements a routing table that maps the destination address of a packet to a rule for forwarding that packet. In a wired network, the routing table specifies the outgoing link on which to forward a […]

Wireline Network Models

The aim of this topic is to develop a common framework for analyzing capacities of wireline and wireless networks. Our focus will, in fact, be on physical- and link-layer issues for wireless problems. However, there are close relations between wireline and wireless networks that we wish to highlight, and that we hope will lead to […]

Wireless Channel Models (Network Models)

Wireless channels have been the subject of a large body of research, including both analytic and empirical modeling; see [61, 151, 178] and references therein. Consider, for instance, the wireless network depicted on the left in Figure 3.5. The signals transmitted by the devices are bandlimited and can, by Nyquist sampling theory, be represented by […]

Wireless Device Models (Network Models)

Wireless devices usually have several types of constraints. A commonly studied constraint is that the powers (or energies) of the inputs satisfy (see (2.4)) A more severe type of constraint is where the per-symbol energy is constrained. A second constraint is similar to the wireline port constraint (3.1). Note that the model defined by (3.3a) […]

Wireless Capacity and Channel State Information (Network Models)

The direct application of Shannon’s theory, as early as Shannon’s own work [166], provided the capacity measure now often called ergodic capacity [19, 24, 62]. The ergodic capacity is the maximum achievable time-average rate of reliable communication, and it is appropriate when the receiver observes a typical sequence of channel states during the reception of […]

Mixed Networks (Network Models)

A mixed wireline/wireless network and its graph is shown in Figure 3.6. Note that the graphs for the networks of Figures 3.4 and 3.6 are the same, but they are interpreted differently. In general, we will say that every node u has one channel input Xu and one channel output Yu. We draw a directed […]