On the throughput, capacity, and stability regions of random multiple access
IEEE/ACM Transactions on Networking (TON) - Special issue on networking and information theory
Slotted gaussian multiple access channel: stable throughput region and role of side information
EURASIP Journal on Wireless Communications and Networking - Theory and Applications in Multiuser/Multiterminal Communications
Loss performance model for wireless channels with autocorrelated arrivals and losses
Computer Communications
On multiple access random medium access control
ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3
On queueing and multilayer coding
IEEE Transactions on Information Theory
Admission control for multiple access in fading G-IC networks
MILCOM'09 Proceedings of the 28th IEEE conference on Military communications
Bounded-contention coding for wireless networks in the high SNR regime
DISC'12 Proceedings of the 26th international conference on Distributed Computing
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We study different notions of capacity for time-slotted ALOHA systems. In these systems, multiple users synchronously send packets in a bursty manner over a common additive white Gaussian noise (AWGN) channel. The users do not coordinate their transmissions, which may collide at the receiver. For such a system, we define both single-slot capacity and multiple-slot capacity. We then construct a coding and decoding scheme for single-slot capacity that achieves any rate within this capacity region. This coding and decoding scheme for a single time slot combines aspects of multiple access rate splitting and of broadcast codes for degraded AWGN channels. This design allows some bits to be reliably received even when collisions occur and more bits to be reliably received in the absence of collisions. The exact number of bits reliably received under both of these scenarios is part of the code design process, which we optimize to maximize the expected rate in each slot. Next, we examine the behavior of the system asymptotically over multiple slots. We show that there exist coding and decoding strategies such that regardless of the burstiness of the traffic, the system is stable as long as the average rate of the users is within the multiple access capacity region of the channel. In other words, we show that bursty traffic does not decrease the Cover-Wyner capacity region of the multiple access channel. A vast family of codes, which includes the type of codes we introduce for the single-slot transmission, achieve the capacity region, in a sense we define, for multiple-slot transmissions. These codes are stabilizing, using only local information at each of the individual queues. The use of information regarding other queues or the use of scheduling does not improve the multiple-slot capacity region.