Performance Analysis of IP based WSNs in real time systems

Wireless sensor networks (WSNs) are the key enablers of the internet of things (IoT) paradigm. Traditionally, sensor network research has been to be unlike the internet, motivated by power and device constraints. The IETF 6LoWPAN draft standard changes this, defining how IPv6 packets can be efficiently transmitted over IEEE 802.15.4 radio links. Due to this 6LoWPAN technology, low power, low cost micro- controllers can be connected to the internet forming what is known as the wireless embedded internet. Another IETF recommendation, CoAP allows these devices to communicate interactively over the internet. The integration of such tiny, ubiquitous electronic devices to the internet enables interesting real-time applications. This thesis work attempts to evaluate the performance of a stack consisting of CoAP and 6LoWPAN over the IEEE 802.15.4 radio link using the Contiki OS and Cooja simulator, along with the CoAP framework Californium (Cf). Ultimately, the implementation of this stack on real hardware is carried out using a raspberry pi as a border router with T-mote sky sensors as slip radios and CoAP servers relaying temperature and humidity data. The reliability of the stack was also demonstrated during scalability analysis conducted on the physical deployment. The interoperability is ensured by connecting the WSN to the global internet using different hardware platforms supported by Contiki and without the use of specialized gateways commonly found in non IP based networks. This work therefore developed and demonstrated a heterogeneous wireless sensor network stack, which is IP based and conducted performance analysis of the stack, both in terms of simulations and real hardware.

Territorial development, planning reform and urban governance: the case of Ireland's second-tier cities

The increased emphasis within Europe on the role of second-tier cities has implications for the ways in which these urban centres are considered within national spatial planning strategies. In centralised, monocentric states like Ireland, there has been a general ambivalence towards urban policy for cities outside the capital city, and historically this has prevented the development of a strong, diversified urban hierarchy undermining prospects for balanced regional development. This paper examines the extent to which a new found emphasis on Ireland’s second-tier cities which emerged in the ‘Gateways’ policy of the National Spatial Strategy (NSS, 2002) was matched by subsequent political and administrative commitment to facilitate the development of these urban centres. Following a discussion of the position of second-tier cities in an international context and a brief overview of recent demographic and economic trends, the paper assesses the relative performance of Ireland’s second-tier cities in influencing development trends, highlighting a comprehensive failure to deliver compact urban growth. In this context, the paper then discusses the implications of current development plans for the second-tier cities and proposals for Irish local government reform for securing compact urban development.