Domenico Garlisi - PhD Thesis - PDF - PRESENTATION

Abstract: Wireless networks importance for the future Internet is raising at a fast pace as mobile devices increasingly become its entry point. Wireless local area networks are becoming more and more important for providing wideband wireless local access thanks to the impressive success of cheap technologies, such as the IEEE 802.11, working on unlicensed bands. Because of the different application and networking scenarios, several standard extensions have been added to the original 802.11 technology (born as a standard for just cable replacement) with significant standardization efforts. Indeed, wireless service scenarios and application contexts evolve continuously and in an unpredictable way, and require significant and fast amendments of the underlying protocols. In this thesis we face the problem of wireless network programmability as a solution for coping with context-dependent optimizations, moving from one-for-all standard solutions to the concept of programmable wireless interfaces. Although the wireless research and academic community has proposed interesting platforms (e.g. based on Software Defined Radio) for pushing forward dynamic reprogrammability of devices, we argue that it is important to identify a tradeoff between programmability space and usability of the programmable interface. In this direction, we introduce the concept of Wireless MAC Processor and developed a running prototype over an ultra-cheap wireless card. Wireless MAC processor is a programmable device which provides a set of stateless Medium Access Control commands, and which embeds a MAC protocol engine in charge of executing a finite state machine able to exploit and compose the sequence of commands forming a desired MAC protocol logic. Wireless MAC Processor (WMP) commands can be considered analogous to the instruction set of an ordinary CPU. They are meant to implement elementary actions, namely MAC operations such as transmit a frame, set timers, etc., which may be then executed in the appropriate sequence and/or under the occurrence of specific events and conditions mandated by a protocol logic. Instead of implementing a specific Medium Access Control (MAC) protocol stack, Wireless MAC processors do support a set of Medium Access Control which can be run-time composed (pro- grammed) through Finite State Machine (FSM), thus providing the desired MAC protocol opera- tion. Flexibility and ease of programmability is thus a consequence of the clear architecture-level decoupling made between what the device is able to do (the pre-installed MAC commands), and what it is instructed at run time, to do (the injected state machine).

 

Fabrizio Giuliano - PhD Thesis - PDF - PRESENTATION

Abstract: Mobile networks for Internet Access are a fundamental segment of Internet access net- works, where resource optimization are really critical because of the limited bandwidth availability. While traditionally resource optimizations have been focused on high e- cient modulation and coding schemes, to be dynamically tuned according to the wireless channel and interference conditions, it has also been shown how medium access schemes can have a signi cant impact on the network performance according to the application and networking scenarios. This thesis work proposes an architectural solution for supporting Medium Access Con- trol (MAC) recon gurations in terms of dynamic programming and code mobility. Since the MAC protocol is usually implemented in rmware/hardware (being constrained to very strict reaction times and to the rules of a speci c standard), our solution is based on a di erent wireless card architecture, called Wireless MAC Processor (WMP), where standard protocols are replaced by standard programming interfaces . The control architecture developed in this thesis exploits this novel behavioral model of wireless cards for extending the network intelligence and enabling each node to be remotely reprogrammed by means a so called \MAC Program", i.e. a software element that de nes the description of a MAC protocol. This programmable protocol can be remotely injected and executed on running network devices allowing on-the- y MAC recon gurations. This work aim to obtain a formal description of the a software de ned wireless network requirements and de ne a mechanism for a reliable MAC program code mobility throw the network elements, transparently to the upper-level and supervised by a global con- trol logic that optimizes the radio resource usage; it extends a single protocol paradigm implementation to a programmable protocol abstraction and rede nes the overall wire- less network view with support for cognitive adaptation mechanisms. The envisioned solutions have been supported by real experiments running on di erent WMP proto- types , showing the bene ts given by a medium control infrastructure which is dynamic, message-oriented and recon gurable.

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