arXiv subjects

Jean Walrand

Publications and source records attributed to Jean Walrand.

21 records · Page 2Linked to original sources

arXiv2010

Optimism in Games with Non-Probabilistic Uncertainty

The paper studies one-shot two-player games with non-Bayesian uncertainty. The players have an attitude that ranges from optimism to pessimism in the face of uncertainty. Given the attitudes, each player forms a belief about the set of possible strategies of the other player. If these beliefs are consistent, one says that they form an uncertainty equilibrium. One then considers a two-phase game where the players first choose their attitude and then play the resulting game. The paper illustrates these notions with a number of games where the approach provides a new insight into the plausible strategies of the players.

cs.GT↗

arXiv2009

Distributed Random Access Algorithm: Scheduling and Congesion Control

This paper provides proofs of the rate stability, Harris recurrence, and epsilon-optimality of CSMA algorithms where the backoff parameter of each node is based on its backlog. These algorithms require only local information and are easy to implement. The setup is a network of wireless nodes with a fixed conflict graph that identifies pairs of nodes whose simultaneous transmissions conflict. The paper studies two algorithms. The first algorithm schedules transmissions to keep up with given arrival rates of packets. The second algorithm controls the arrivals in addition to the scheduling and attempts to maximize the sum of the utilities of the flows of packets at the different nodes. For the first algorithm, the paper proves rate stability for strictly feasible arrival rates and also Harris recurrence of the queues. For the second algorithm, the paper proves the epsilon-optimality. Both algorithms operate with strictly local information in the case of decreasing step sizes, and operate with the additional information of the number of nodes in the network in the case of constant step size.

cs.IT↗

arXiv2007

Distributed Fair Scheduling Using Variable Transmission Lengths in Carrier-Sensing-based Wireless Networks

The fairness of IEEE 802.11 wireless networks (including Wireless LAN and Ad-hoc networks) is hard to predict and control because of the randomness and complexity of the MAC contentions and dynamics. Moreover, asymmetric channel conditions such as those caused by capture and channel errors often lead to severe unfairness among stations. In this paper we propose a novel distributed scheduling algorithm that we call VLS, for ``{\em variable-length scheduling}'', that provides weighted fairness to all stations despite the imperfections of the MAC layer and physical channels. Distinct features of VLS include the use of variable transmission lengths based on distributed observations, compatibility with 802.11's contention window algorithm, opportunistic scheduling to achieve high throughput in time-varying wireless environments, and flexibility and ease of implementation. Also, VLS makes the throughput of each station more smooth, which is appealing to real-time applications such as video and voice. Although the paper mostly assumes 802.11 protocol, the idea generally applies to wireless networks based on CSMA (Carrier Sensing Multiple Access).

cs.NI↗