In this paper, a simple decentralized power allocation strategy is proposed, which relies on the local information in a single-hop wireless network with n links. The main goal of the strategy is to improve the average sum-rate. We first define a new utility-based framework, in which each user takes into account the negative impact of its power increment on the other users performance. For large n and by knowing only the direct channel gain hii, the optimum strategy for user i is to transmit with full power or remain silent. The transmission policy is to compare hii with a prespecified threshold τn that is a function of n. Under a Rayleigh fading channel condition, it is demonstrated that among n pairs of nodes, the average number of active links is of order log n. Also, the average sum-rate scales as Θ(log n). The performance of the proposed strategy is compared with that of the centralized power allocation scheme and the non-cooperative power control games through simulation and the analytical arguments. The proposed on-off power allocation scheme has the advantage of not requiring a central controller. The proposed strategy relies on a one shot game with a simple structure, rather than the iterative mechanism used in the pricing algorithm. These properties make our scheme more practical in time-varying networks.

We describe some “unrestricted” algorithms which are useful for the computation of elementary and special functions when the precision required is not known in advance. Several general classes of algorithms are identified and illustrated by examples. Applications of such algorithms are mentioned.

This paper presents an analysis of the control overhead involved in clustering and routing for one-hop clustered mobile ad hoc networks. Previous work on the analysis of control overhead incurred by clustering algorithms focused mainly on the derivation of control overhead in the Knuth big-O notation with respect to network size. However, we observe that the control overhead in a clustered network is closely related to different network parameters, e.g. node mobility, node transmission range, network size, and network density. This paper presents an analysis that captures the effects of different network parameters on the control overhead. The results of our work can provide valuable insights into the amount of overhead that clustering algorithms may incur in different network environments. This facilitates the design of efficient clustering algorithms in order to minimize the control overhead.

A random rectangle is the product of two independent random intervals, each being the interval between two random points drawn independently and uniformly from [0; 1]. We prove that the number C n of items in a maximum cardinality disjoint subset of n random rectangles satisfies n 1=2 =K EC n Kn 1=2 ; where K is an absolute constant. Although tight bounds for the problem generalized to d ? 2 dimensions remain an open problem, we are able to show that, for some absolute constant K, n 1=2 =K EC n K(n log d\Gamma1 n) 1=2 : Finally, for a certain distribution of random cubes we show that for some absolute constant K, the number Q n of items in a maximum cardinality disjoint subset of the cubes satisfies n d=(d+1) =K EQ n Kn d=(d+1) : 5 The research of this author was done while at Bell Labs, Lucent Technologies. 6 The research of this author was partially done while visiting DIMACS on a sabbatical in Fall 1998. 1 1 Introduction We estimate the expected number ...

A single-hop wireless network with K links is considered, where the links are partitioned into M clusters, each operating in a subchannel with bandwidth W M. We assume that the links in each cluster perform the on-off power allocation strategy proposed in [1]. The problem is to analyze the average sum-rate of the network in terms of M and under the shadow-fading effect with probability α. It is demonstrated that for M ∼ o(K) and 0 < α ≤ 1, where α is fixed, the average sum-rate of the network scales as W α K log

In this paper, an asymptotic analysis for the delay-throughput of a single-hop wireless network with n pairs of nodes is presented. The analysis relies on the decentralized on-off power allocation strategy, in which the on-off transmission policy for each link is based on comparing its direct channel gain with optimum threshold τn. We first provide a new definition of the transmission delay in a homogenous network. It is proved that the delay threshold level that results the dropping probability for each link tends to zero, while achieving the maximum average sum-rate scales as ω(n / log n). Also, the minimum delay in order to make the dropping probability for the whole network approach zero scales as ω(n / log n) + n. Furthermore, we drive lower and upper bounds for the link activation probability, q, such that the order of the average sum-rate is preserved. Based on the upper bound on q, an asymptotic analysis shows that the delay in each link and in the network improves without any significant impact on the the average sum-rate. Finally, we present a new definition of the throughput for the link in the cases of one and infinite buffer size. It is demonstrated that the maximum average throughput of the network with the decentralized on-off power allocation strategy is independent of the buffer size.

Abstract. We present in this paper a proposal for developing efficient programs in the abstract data type (ADT) programming framework, keeping the modular structure of programs and without violating the information hiding principle. The proposal focuses in the concept of &quot;shortcut &quot; as an efficient way of accessing to data, alternative to the access by means of the primitive operations of the ADT. We develop our approach in a particular ADT, a store of items. We define shortcuts in a formal manner, using algebraic specifications interpreted with initial semantics, and so the result has a well-defined meaning and fits in the ADT framework. Efficiency is assured with an adequate representation of the type, which provides O(1) access to items in the store without penalising the primitive operations of the ADT. 1

This paper compares the performance, in highly-parallel shared-memory multiprocessors, of locating translation-lookaside buffers (TLBs) at processors with that of locating TLBs at memory. Our performance comparison is based on results of trace-driven simulations of multiprocessors with logN-stage networks interconnecting N processors and N memory modules. For the systems and workloads studied, memory-based TLBs perform better than processor-based TLBs, provided that memory is organized as multiple paging arenas, where the mapping of pages to arenas is fixed. The cost of a processor-based TLB reload is at least logN because of network transit. The cost of a memory-based TLB reload can be made smaller than that of a processor-based TLB reload, since network transits are not required. Furthermore, with multiple paging arenas, the number of reloads is smaller with memory-based TLBs. For memory-based TLBs to continue to outperform processor-based TLBs for large N, it is likely that the numb...

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Abstract — We study the benefits of opportunistic routing in wireless networks by examining how the power and delay scale as the number of source-destination (S-D) pairs increases, where S-D pairs are randomly located over the network. The scaling behavior of conventional multi-hop transmission that does not employ opportunistic routing is also examined. The results indicate that the opportunistic routing can exhibit better powerdelay trade-off than the conventional routing while providing up to a logarithmic boost in the scaling law. The gain comes from the fact that the system with opportunistic routing can tolerate more interference due to increased received signal power from utilizing the multi-user diversity gain. Furthermore, we derive an upper bound on the total throughput using the cut-set theorem. It is shown that the achievable rates of the conventional and opportunistic routing schemes become close to the upper bound when the number of S-D pairs is large enough. I.