93,785 research outputs found
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
On Modeling Coverage and Rate of Random Cellular Networks under Generic Channel Fading
In this paper we provide an analytic framework for computing the expected
downlink coverage probability, and the associated data rate of cellular
networks, where base stations are distributed in a random manner. The provided
expressions are in computable integral forms that accommodate generic channel
fading conditions. We develop these expressions by modelling the cellular
interference using stochastic geometry analysis, then we employ them for
comparing the coverage resulting from various channel fading conditions namely
Rayleigh and Rician fading, in addition to the fading-less channel.
Furthermore, we expand the work to accommodate the effects of random frequency
reuse on the cellular coverage and rate. Monte-Carlo simulations are conducted
to validate the theoretical analysis, where the results show a very close
match
Unsaturated Throughput Analysis of IEEE 802.11 in Presence of Non Ideal Transmission Channel and Capture Effects
In this paper, we provide a throughput analysis of the IEEE 802.11 protocol
at the data link layer in non-saturated traffic conditions taking into account
the impact of both transmission channel and capture effects in Rayleigh fading
environment. The impact of both non-ideal channel and capture become important
in terms of the actual observed throughput in typical network conditions
whereby traffic is mainly unsaturated, especially in an environment of high
interference.
We extend the multi-dimensional Markovian state transition model
characterizing the behavior at the MAC layer by including transmission states
that account for packet transmission failures due to errors caused by
propagation through the channel, along with a state characterizing the system
when there are no packets to be transmitted in the buffer of a station.
Finally, we derive a linear model of the throughput along with its interval of
validity.
Simulation results closely match the theoretical derivations confirming the
effectiveness of the proposed model.Comment: To appear on IEEE Transactions on Wireless Communications, 200
Exploiting Capture Effect in Frameless ALOHA for Massive Wireless Random Access
The analogies between successive interference cancellation (SIC) in slotted
ALOHA framework and iterative belief-propagation erasure-decoding, established
recently, enabled the application of the erasure-coding theory and tools to
design random access schemes. This approach leads to throughput substantially
higher than the one offered by the traditional slotted ALOHA. In the simplest
setting, SIC progresses when a successful decoding occurs for a single user
transmission. In this paper we consider a more general setting of a channel
with capture and explore how such physical model affects the design of the
coded random access protocol. Specifically, we assess the impact of capture
effect in Rayleigh fading scenario on the design of SIC-enabled slotted ALOHA
schemes. We provide analytical treatment of frameless ALOHA, which is a special
case of SIC-enabled ALOHA scheme. We demonstrate both through analytical and
simulation results that the capture effect can be very beneficial in terms of
achieved throughput.Comment: Accepted for presentation at IEEE WCNC'14 Track 2 (MAC and
Cross-Layer Design
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