Achievable rates and outage probability of cognitive radio with dynamic frequency hopping under imperfect spectrum sensing

In this study, the authors propose simple methods to evaluate the achievable rates and outage probability of a cognitive radio (CR) link that takes into account the imperfectness of spectrum sensing. In the considered system, the CR transmitter and receiver correlatively sense and dynamically exploit the spectrum pool via dynamic frequency hopping. Under imperfect spectrum sensing, false-alarm and miss-detection occur which cause impulsive interference emerged from collisions due to the simultaneous spectrum access of primary and cognitive users. That makes it very challenging to evaluate the achievable rates. By first examining the static link where the channel is assumed to be constant over time, they show that the achievable rate using a Gaussian input can be calculated accurately through a simple series representation. In the second part of this study, they extend the calculation of the achievable rate to wireless fading environments. To take into account the effect of fading, they introduce a piece-wise linear curve fitting-based method to approximate the instantaneous achievable rate curve as a combination of linear segments. It is then demonstrated that the ergodic achievable rate in fast fading and the outage probability in slow fading can be calculated to achieve any given accuracy level.

From brown envelopes to community benefits: the co-option of planning gain agreements under deepening neoliberalism

The provision of physical and social infrastructure in the form of roads, green spaces and community facilities has traditionally been provided for by the state through the general taxation system. However, as the state has been transformed along more neoliberal lines, the private sector is increasingly relied upon to deliver public goods and services. Planning gain agreements have flourished within this context by offering another vehicle through which local facilities are privately funded. Whilst these agreements reflect the broader dynamics of neoliberalism, they are commonly viewed as a tool which can be employed to challenge these very dynamics by empowering local communities to secure more just planning outcomes. This paper counters such claims. Based on evidence gathered from 80 interviews with planners, councillors, developers and community groups in Ireland, the paper demonstrates how planning gain agreements have been strategically redeployed by the holders of political and economic power to serve their own ends. In seeking to understand why and how this has occurred, specific consideration is given to the changing power dynamics between the state and private capital under neoliberalism. The paper highlights how institutional arrangements have enabled developers to infiltrate the political sphere in more subtle and implicit ways than ever before. We conclude by arguing that planning gain must be understood as a mechanism which has been manipulated in ways which essentially work to preserve and enhance, rather than redress, existing power imbalances in the planning system by facilitating large scale transfers of wealth upwards in society.