Chapter 7
Conclusion

The book was opened with a comprehensive depiction of the concept of autonomic computing from the perspective of a modern networked system design, where the notion of the human autonomic nervous system was elevated with emphasis on the key dimensions to self-management in the form of self-configuration, self-optimisation, self-healing, and self-protection, yet keeping in mind the context of agent systems. In order to prepare the ground for the target Autonomic Cooperative Networking Architectural Model, the Generic Autonomic Network Architecture was characterised through analysis of role of decision elements and hierarchical autonomic control loops, as well as their respective levels of abstraction, arranged in an incremental order. In this respect, the Vertical Technological Pillars and the Horizontal Architectural Extensions were introduced, given the perpendicularity of the layers of the Open Systems Interconnection Reference Model and the levels of the Generic Autonomic Network Architecture, as were the architectural constituents in the form of the Autonomic Cooperative Node, the Autonomic Cooperative Behaviour, and the Autonomic Cooperative Networking Protocol. The protocol level cooperative transmission decision element was presented, with its responsibility for cooperative relaying. Next, the function level cooperative re-routing decision element was deployed as a trigger for resiliency driven cooperative re-routing. Moving forward, the node level cooperation management decision element was introduced to integrate routing mechanisms. Finally, the network level cooperation orchestration decision element was outlined to comprehensively oversee the overall system.

The focus then shifted to spatio-temporal processing, with the initial emphasis on the multiple-input multiple-output radio channel. Then, the diversity related aspects were discussed to justify the role of and the necessity for the later deployment of spatio-temporal processing, as well as the singular-value decomposition theorem was explained to introduce the equivalent virtual multiple-input multiple-output radio channel along with its capacity proved to scale linearly with the number of generic transmitters or generic receivers. Moreover, an external model for radio channel coefficient calculation was described, as well as the difference between coding gain and diversity gain was addressed. Going further, special attention was paid to the technology of space-time block coding, where the question of its being perceived more as a modulation than a coding technique was visited, the derivation process of the decoding metrics for a selected set of code matrices was outlined with the aim of clarifying certain inconsistencies existing in the source materials, and the extension towards space-time trellis coding was presented to account for additional coding gain. Moving to the architectural integration aspects, the notion and internal structure of the Autonomic Cooperative Node was introduced, where the discussion of the relation between autonomics and cooperation was triggered. Finally, the cooperative transmission decision element of the protocol level was analysed along with specifically tailored adaptive logic allowing the switching of relevant code matrices on the basis of the radio channel parameters, and the pertinent architectural integration aspects were addressed to pave the way for further extensions.

Moving forward, both conventional relaying and cooperative relaying were addressed from the classificatory perspective, as well as supportive protocols and collaborative protocols were introduced as specifically interrelated subcategories of the generic cooperative protocol. Going further, the concept of multi-tier virtual antenna arrays was outlined, where the special operation mode, in the form of distributed space-time block coding, was discussed. Next, the attention was shifted towards a fixed deployment concept of a grid-based Manhattan scenario characterised by the fact that although the pattern formed by the buildings could become critically important for the suppression of interference among the fixed relay nodes, making it impossible to exercise any cooperative relaying based on virtual antenna arrays among the same, certain adaptation with regard to the framing structure and the buffer memory could still prove advantageous. Similarly, a cooperation enabled relay-enhanced cell indoor scenario was analysed, where the major emphasis was put on the aspects related to the link layer. Then the focus shifted towards the function level overlay logic to encompass the roots of Autonomic Cooperative Behaviour, including its enablers and the role of the equivalent distributed space-time block encoder in particular. Consequently, the cooperative re-routing decision element was presented, including not only its transition from the node level to the function level, but also the logic behind cooperative re-routing. Finally, the architectural integration aspects were discussed and complemented with the introduction of an extended version of the Autonomic Cooperative Node.

Going further, the workings of the Optimised Link State Routing protocol were discussed along with its multi-point relay station selection heuristics and information storage repositories, to provide the required context for further developments and to arrange for the later introduction of the virtual antenna array selector set and its related virtual antenna array selector tuples. Then came an analysis of the algorithmic description of the related routing information enhanced algorithm for cooperative transmission as the method for applying additional network layer information to enable and orchestrate cooperative transmission at the link layer, subsequently upgraded to the extended routing information enhanced algorithm for cooperative transmission along with its evolved messaging structure in order to lay the groundwork for the target Autonomic Cooperative Networking Protocol. In this respect, both address auto-configuration and duplicate address detection were discussed before the focus shifted towards the umbrella formed by the function level overlay logic, where the workings of the Autonomic Cooperative Networking Protocol were outlined to justify the place of the evolved messaging structure in the process of Autonomic Cooperative Node preselection, together with the layout of the routing table. Next, the extended algorithmic description of the cooperation management decision element was scrutinised not only to evaluate its advantages, but also to address the protocol overhead aspects. Finally, once again, the question of architectural integration was visited, involving the conceptual transitions and the dependencies among the related entities.

Eventually, the standardisation-orientated design was outlined, where the research and investment perspective accounted for the place of the Autonomic Cooperative Networking Architectural Model, not only by referring to the Open Systems Interconnection Reference Model and emphasising the instantiation of the Generic Autonomic Network Architecture along with its levels of abstraction, but also introducing certain cross-specification considerations related to software-defined networking, machine-to-machine communications, and intelligent transport systems. Next, the attention was shifted to emergency communications network, characterised by specifically tailored requirements making the system operation dependent on the hierarchy between chief first responders and their respective first responders, where the cooperative mode of operation, supported with performance evaluation analysis, was introduced. The proactive and reactive resiliency process was also outlined, to allow proper integration into the Autonomic Cooperative Networking Architectural Model. Then, the related network level overlay logic was brought up to explain the mutual relation between the Autonomic Cooperative Networking Protocol and Autonomic Cooperative Behaviour, as well as the cooperation orchestration decision element was introduced from the viewpoint of providing prioritisation between the two. Last, but not least, the relay-enhanced cell scenario was revisited for a more accurate evaluation of the second hop, and the concluding architectural integration aspects were raised to ensure the overall consistency of the proposed depiction of the Autonomic Cooperative Networking Architectural Model.

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