A Distributed Scheduling Algorithm to Provide Quality-of-Service in Multihop Wireless Networks

Control of multihop Wireless networks in a distributed manner while providing end-to-end delay requirements for different flows, is a challenging problem. Using the notions of Draining Time and Discrete Review from the theory of fluid limits of queues, an algorithm that meets delay requirements to various flows in a network is constructed. The algorithm involves an optimization which is implemented in a cyclic distributed manner across nodes by using the technique of iterative gradient ascent, with minimal information exchange between nodes. The algorithm uses time varying weights to give priority to flows. The performance of the algorithm is studied in a network with interference modelled by independent sets

Future Targets and Multiple Equilibria

Multiple Pareto-rankable equilibria may obtain in an overlapping generations model where consumers save to reach a fixed target. Existence and uniqueness conditions are discussed. The model displays excess consumption sensitivity to current income and perfect old-age insurance.Multiple equilibria, saving, overlapping generations, excess sensitivity.

Trade, Growth and Increasing Returns to Infrastructure : The Role of the Sophisticated Monopolist

We model an economy with two final goods, manufactures produced under IRS and food. The scale economies in manufacturing are external (therefore compatible with perfect competition) and traceable to internal economies in the provision of an infrastructural service (the third sector of the economy). We examine the equilibria of this economy under both autarky and free trade. We thus revisit a theme with a voluminous literature, beginning with R. C. O. Matthews(1950) vintage classic and including, among others, Panagariya (1991), Krugman (1991), and Venables (1996). Much of this as well as our own work concerns multiple equilibria : it overlaps the development literature on poverty traps from Rosenstein Rodan (1943) to Murphy, Schleifer and Vishny (1989). We differ from this body of work in a major, and some minor, respects. We trace the source of increasing returns to infrastructure, and our focus is on the role of the infrastructure providers beliefs in determining the equilibrium and the fate of the economy. Internal economies in infrastructure provision ensure that it is non-competitive . We consider a pure monopoly. The infrastructure provider is of course aware of the impact of his decisions on the price of his services, but he may or may not appreciate their impact, on demand for labor (in a market where he competes with all other industrial and agricultural producers) and wages and induced effects on demand for infrastructure itself. He may in short be a nave or a sophisticated decision-maker. We model the nave infrastructure provider after Venables (1996). Venables portrays a producer of intermediates who derives the demand curve for his product on the assumption that his customers have already contracted for their purchases of other inputs, specifically labor. Similar beliefs on the part of our infrastructure provider generate an equilibrium that is unique in the closed economy. In the small open economy, on the other hand, equilibria, where they exist , will generally be multiple : at any world price, there will generally exist one at a low level with unexhausted scale economies and another at a high level where these have been exhausted.Increasing returns to scale, cognitive hierarchy, multiple equilibria, uniqueness, Cournot oligopoly

Target Saving In An Overlapping Generations Model

We examine a model in which the utility function has been engineered so that it is optimal for consumers to aim for a fixed target level of retirement resources. In this case consumption displays excess sensitivity to current income as well as perfect old age insurance. In an overlapping generations model, this leads naturally to multiple and unstable equilibria. Under static expectations, it also leads to a well-defined dynamics, including possible historical traps, implosions involving ever-diminishing capital stock and ever-increasing interest rates, and the feasibility of optimal one-time interventions.Targets, history, excess sensitivity, static expectations, rational expectations, uniqueness.

Cosigned Or Group Loans

We analyze lending contracts when social sanctions are used to enforce repayments and borrowers differ in their unobserved sanctioning abilities. Symmetric group loans are preferred to cosigned loans when borrowers are relatively equal, and cosigned loans are preferred when borrowers are unequal. This explains why microlenders that target the poor (e.g., the Grameen Bank) use symmetric group loans while other untargeted lenders use cosigned loans. Complicated menus of loan contracts that induce borrowers to self select can do no better than these simple loan contracts unless borrowers are very productive. In particular, we explain why group lending arrangements offering different loan terms to members of the same group are seldom observed.Microcredit, Social Sanctions, Grameen Bank