Pareto Boundary of the Rate Region for Single-Stream MIMO Interference Channels: Linear Transceiver Design

We consider a multiple-input multiple-output (MIMO) interference channel (IC), where a single data stream per user is transmitted and each receiver treats interference as noise. The paper focuses on the open problem of computing the outermost boundary (so-called Pareto boundary-PB) of the achievable rate region under linear transceiver design. The Pareto boundary consists of the strict PB and non-strict PB. For the two user case, we compute the non-strict PB and the two ending points of the strict PB exactly. For the strict PB, we formulate the problem to maximize one rate while the other rate is fixed such that a strict PB point is reached. To solve this non-convex optimization problem which results from the hard-coupled two transmit beamformers, we propose an alternating optimization algorithm. Furthermore, we extend the algorithm to the multi-user scenario and show convergence. Numerical simulations illustrate that the proposed algorithm computes a sequence of well-distributed operating points that serve as a reasonable and complete inner bound of the strict PB compared with existing methods.Comment: 16 pages, 9 figures. Accepted for publication in IEEE Tans. Signal Process. June. 201

Development of a decision making tool for waste management: case study of a local authority in Wales

The landscape for waste collection is ever changing. With constant adjustments in Government, increasing budget restrictions and changes in Legislation, Local Authorities have to adapt their collection methods to achieve the best recycling rates possible. The focus of their efforts is frequently on the cost; however there are many other drivers and barriers that they must pay attention to such as legislative compliance. The aim of this study was to understand the interaction of these drivers and barriers. More specifically, the decision making process that they follow. A long term, consistent decision making process is required to maximise the amount of recyclate they can collect. A study of the decision making methodologies showed that the Analytic Hierarchy Process (AHP) was the easiest to understand and implement. By having an understandable methodology, the decision maker(s) have clarity and a solid reasoning for the choice they make. Also, by using a commonly understood software to create a programme meant a clear understanding and ownership of the decision made. Scenarios were created to understand how the criteria interact and affect the choice of waste collection method. The interaction of criteria dependent on the size and type of Local Authorities was examined. Of all the criteria that could be taken in to consideration, Legislative Compliance, Net Running Costs and the Quality of the Recyclate collected were repeatedly the most important. The results gathered from the Case Study Authority were checked against these scenarios and it was found that they performed in the same manner that was expected from their classification by type and size of authority. It was concluded that the decision making process, as a whole and in relation to waste management, was successfully understood. The novel development of the Analytic Hierarchy Process and inception of a decision making tool to clearly define the drivers and barriers that face a Local Authority were accomplished. The time sensitive nature of the process highlighted the difficulty assuring the right decision is made at any given time. Nevertheless, it was successfully applied to a Case Study Authority whose decision matched the ideals of the Welsh Government in suggesting a Kerbside Sort collection scheme