10 - WPNC in Complex Stochastic Networks

Summary

Principles of Wireless Cloud Coding

The termWireless Cloud Coding (WCC) will denote the coding concept suited for large and complex networks with a stochastic structure and connectivity. A simple low-scale WPNC network with a known deterministic structure can be designed in a “handcrafted” style.We usually also easily identify the critical points of performance or design aspects that need to be optimized. On the other hand, a complex large stochastic network adds some specific problems.

Stochastic Network Structure

The network structure and connectivity may be stochastic and unknown. A standard NCM design needs to know the participating signals forming the H-constellation in the H-MAC stage, and also the full end-to-end hierarchical encapsulation of all involved HNC maps to guarantee the end-to-end solvability. In a large randomly changing network, this creates a significant problem for (a) identifying and estimating the system/ channel state, (b) making a decision on the processing form, and (c) signaling this decision to all involved nodes. Instead of using this traditional solution, we can try to devise the NCM that is blind to the network structure that will not require a separate NCM/WPNC control protocol but will treat the unknown network structure as an additional degree of freedom fully integrated with the actual payload data (see Section 10.2).

Clustered, Nested, and Modular Cloud Framework

The number of the design degrees of freedom may be prohibiting in a large network. A nested modular encapsulation of some of its fragments/clusters can help. This has two aspects. (a) It simplifies the overall design by clustering the nodes and nesting the clusters. (b) Each cluster performs some processing as a “black-box” self-contained virtual super-node. It does not reveal its internal structure to the outside world and simply provides some functionality as a super-node. Its global level of clustering can even comprise the whole cloud. It can serve its outside terminals as if it was some super-relay performing some complex internal hidden processing (see Section 10.3).

Wireless Cloud-Coding-Based Design of NCM

Random Channel Class H-MAC and Joint HNC Map

Joint HNC map vs. Classical Signaling

A classical signaling solution (Figure 10.1a) is based on the channel sensing and then switching the NCM map at the node depending on the channel class (connection/ disconnection).