517 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
Broadcast Coded Slotted ALOHA: A Finite Frame Length Analysis
We propose an uncoordinated medium access control (MAC) protocol, called
all-to-all broadcast coded slotted ALOHA (B-CSA) for reliable all-to-all
broadcast with strict latency constraints. In B-CSA, each user acts as both
transmitter and receiver in a half-duplex mode. The half-duplex mode gives rise
to a double unequal error protection (DUEP) phenomenon: the more a user repeats
its packet, the higher the probability that this packet is decoded by other
users, but the lower the probability for this user to decode packets from
others. We analyze the performance of B-CSA over the packet erasure channel for
a finite frame length. In particular, we provide a general analysis of stopping
sets for B-CSA and derive an analytical approximation of the performance in the
error floor (EF) region, which captures the DUEP feature of B-CSA. Simulation
results reveal that the proposed approximation predicts very well the
performance of B-CSA in the EF region. Finally, we consider the application of
B-CSA to vehicular communications and compare its performance with that of
carrier sense multiple access (CSMA), the current MAC protocol in vehicular
networks. The results show that B-CSA is able to support a much larger number
of users than CSMA with the same reliability.Comment: arXiv admin note: text overlap with arXiv:1501.0338
LPDQ: a self-scheduled TDMA MAC protocol for one-hop dynamic lowpower wireless networks
Current Medium Access Control (MAC) protocols for data collection scenarios with a large number of nodes that generate bursty traffic are based on Low-Power Listening (LPL) for network synchronization and Frame Slotted ALOHA (FSA) as the channel access mechanism. However, FSA has an efficiency bounded to 36.8% due to contention effects, which reduces packet throughput and increases energy consumption. In this paper, we target such scenarios by presenting Low-Power Distributed Queuing (LPDQ), a highly efficient and low-power MAC protocol. LPDQ is able to self-schedule data transmissions, acting as a FSA MAC under light traffic and seamlessly converging to a Time Division Multiple Access (TDMA) MAC under congestion. The paper presents the design principles and the implementation details of LPDQ using low-power commercial radio transceivers. Experiments demonstrate an efficiency close to 99% that is independent of the number of nodes and is fair in terms of resource allocation.Peer ReviewedPostprint (authorâs final draft
A Study of Medium Access Control Protocols for Wireless Body Area Networks
The seamless integration of low-power, miniaturised, invasive/non-invasive
lightweight sensor nodes have contributed to the development of a proactive and
unobtrusive Wireless Body Area Network (WBAN). A WBAN provides long-term health
monitoring of a patient without any constraint on his/her normal dailylife
activities. This monitoring requires low-power operation of
invasive/non-invasive sensor nodes. In other words, a power-efficient Medium
Access Control (MAC) protocol is required to satisfy the stringent WBAN
requirements including low-power consumption. In this paper, we first outline
the WBAN requirements that are important for the design of a low-power MAC
protocol. Then we study low-power MAC protocols proposed/investigated for WBAN
with emphasis on their strengths and weaknesses. We also review different
power-efficient mechanisms for WBAN. In addition, useful suggestions are given
to help the MAC designers to develop a low-power MAC protocol that will satisfy
the stringent WBAN requirements.Comment: 13 pages, 8 figures, 7 table
Energy-efficient wireless communication
In this chapter we present an energy-efficient highly adaptive network interface architecture and a novel data link layer protocol for wireless networks that provides Quality of Service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations in bandwidth scheduling and error control are necessary to achieve energy efficiency and an acceptable quality of service. In our approach we apply adaptability through all layers of the protocol stack, and provide feedback to the applications. In this way the applications can adapt the data streams, and the network protocols can adapt the communication parameters
On the Performance of Irregular Repetition Slotted ALOHA with an Age of Information Threshold
The present paper focuses on an IoT setting in which a large number of
devices generate time-stamped updates addressed to a common gateway. Medium
access is regulated following a grant-free approach, and the system aims at
maintaining an up-to-date knowledge at the receiver, measured through the
average network age of information (AoI). In this context, we propose a
variation of the irregular repetition slotted ALOHA (IRSA) protocol. The
scheme, referred to as age-threshold IRSA (AT-IRSA), leverages feedback
provided by the receiver to admit to the channel only devices whose AoI exceeds
a dynamically adapted target value. By means of detailed networks simulations,
as well as of a simple yet tight analytical approximation, we demonstrate that
the approach can more than halve the average network AoI compared to plain
IRSA, and offers notable improvements over feedback-based state-of-the-art
slotted ALOHA solutions recently proposed in the literature
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