11 research outputs found
Stability Analysis of Frame Slotted Aloha Protocol
Frame Slotted Aloha (FSA) protocol has been widely applied in Radio Frequency
Identification (RFID) systems as the de facto standard in tag identification.
However, very limited work has been done on the stability of FSA despite its
fundamental importance both on the theoretical characterisation of FSA
performance and its effective operation in practical systems. In order to
bridge this gap, we devote this paper to investigating the stability properties
of FSA by focusing on two physical layer models of practical importance, the
models with single packet reception and multipacket reception capabilities.
Technically, we model the FSA system backlog as a Markov chain with its states
being backlog size at the beginning of each frame. The objective is to analyze
the ergodicity of the Markov chain and demonstrate its properties in different
regions, particularly the instability region. By employing drift analysis, we
obtain the closed-form conditions for the stability of FSA and show that the
stability region is maximised when the frame length equals the backlog size in
the single packet reception model and when the ratio of the backlog size to
frame length equals in order of magnitude the maximum multipacket reception
capacity in the multipacket reception model. Furthermore, to characterise
system behavior in the instability region, we mathematically demonstrate the
existence of transience of the backlog Markov chain.Comment: 14 pages, submitted to IEEE Transaction on Information Theor
A 3-player protocol preventing persistence in strategic contention with limited feedback
In this paper, we study contention resolution protocols from a game-theoretic
perspective. In a recent work, we considered acknowledgment-based protocols,
where a user gets feedback from the channel only when she attempts
transmission. In this case she will learn whether her transmission was
successful or not. One of the main results of ESA2016 was that no
acknowledgment-based protocol can be in equilibrium. In fact, it seems that
many natural acknowledgment-based protocols fail to prevent users from
unilaterally switching to persistent protocols that always transmit with
probability 1. It is therefore natural to ask how powerful a protocol must be
so that it can beat persistent deviators.
In this paper we consider age-based protocols, which can be described by a
sequence of probabilities of transmitting in each time step. Those
probabilities are given beforehand and do not change based on the transmission
history. We present a 3-player age-based protocol that can prevent users from
unilaterally deviating to a persistent protocol in order to decrease their
expected transmission time. It is worth noting that the answer to this question
does not follow from the results and proof ideas of ESA2016. Our protocol is
non-trivial, in the sense that, when all players use it, finite expected
transmission time is guaranteed. In fact, we show that this protocol is
preferable to any deadline protocol in which, after some fixed time, attempt
transmission with probability 1 in every subsequent step. An advantage of our
protocol is that it is very simple to describe, and users only need a counter
to keep track of time. Whether there exist -player age-based protocols that
do not use counters and can prevent persistence is left as an open problem for
future research.Comment: arXiv admin note: substantial text overlap with arXiv:1606.0658
Strategic Contention Resolution in Multiple Channels
We consider the problem of resolving contention in communication networks
with selfish users. In a \textit{contention game} each of identical
players has a single information packet that she wants to transmit using one of
multiple-access channels. To do that, a player chooses a
slotted-time protocol that prescribes the probabilities with which at a given
time-step she will attempt transmission at each channel. If more than one
players try to transmit over the same channel (collision) then no transmission
happens on that channel. Each player tries to minimize her own expected
\textit{latency}, i.e. her expected time until successful transmission, by
choosing her protocol. The natural problem that arises in such a setting is,
given and , to provide the players with a common, anonymous protocol (if
it exists) such that no one would unilaterally deviate from it (equilibrium
protocol).
All previous theoretical results on strategic contention resolution examine
only the case of a single channel and show that the equilibrium protocols
depend on the feedback that the communication system gives to the players. Here
we present multi-channel equilibrium protocols in two main feedback classes,
namely \textit{acknowledgement-based} and \textit{ternary}. In particular, we
provide equilibrium characterizations for more than one channels, and give
specific anonymous, equilibrium protocols with finite and infinite expected
latency. In the equilibrium protocols with infinite expected latency, all
players transmit successfully in optimal time, i.e. , with
probability tending to 1 as .Comment: The results of this work are included in the 11th International
Symposium on Algorithmic Game Theory (SAGT 2018) and the 16th Workshop on
Approximation and Online Algorithms (WAOA 2018
Multi-cell Resource Block Allocation Framework
We propose to combine the beamforming technique with Resource Block (RB) allocation algorithms to improve the performance in OFDMA networks. With MIMO antennas, the beamforming technique improves the received signal power which increase the RB's capacity and reduces the neighbouring cell users' interference. When the inter-cell interference channels are known, the beamforming parameters could be applied to the iterative scheduling methods to enhance the performance of the beamforming technique, hence increasing the total system throughput
Der 'kleine Parteitag' in Moskau (28. Juni - 1. Juli 1988)
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