3,598 research outputs found
Full-duplex MAC Protocol Design and Analysis
The idea of in-band full-duplex (FD) communications revives in recent years
owing to the significant progress in the self-interference cancellation and
hardware design techniques, offering the potential to double spectral
efficiency. The adaptations in upper layers are highly demanded in the design
of FD communication systems. In this letter, we propose a novel medium access
control (MAC) using FD techniques that allows transmitters to monitor the
channel usage while transmitting, and backoff as soon as collision happens.
Analytical saturation throughput of the FD-MAC protocol is derived with the
consideration of imperfect sensing brought by residual self- interference (RSI)
in the PHY layer. Both analytical and simulation results indicate that the
normalized saturation throughput of the proposed FD-MAC can significantly
outperforms conventional CSMA/CA under various network conditions
Collision Helps - Algebraic Collision Recovery for Wireless Erasure Networks
Current medium access control mechanisms are based on collision avoidance and
collided packets are discarded. The recent work on ZigZag decoding departs from
this approach by recovering the original packets from multiple collisions. In
this paper, we present an algebraic representation of collisions which allows
us to view each collision as a linear combination of the original packets. The
transmitted, colliding packets may themselves be a coded version of the
original packets.
We propose a new acknowledgment (ACK) mechanism for collisions based on the
idea that if a set of packets collide, the receiver can afford to ACK exactly
one of them and still decode all the packets eventually. We analytically
compare delay and throughput performance of such collision recovery schemes
with other collision avoidance approaches in the context of a single hop
wireless erasure network. In the multiple receiver case, the broadcast
constraint calls for combining collision recovery methods with network coding
across packets at the sender. From the delay perspective, our scheme, without
any coordination, outperforms not only a ALOHA-type random access mechanisms,
but also centralized scheduling. For the case of streaming arrivals, we propose
a priority-based ACK mechanism and show that its stability region coincides
with the cut-set bound of the packet erasure network
ALOHA Random Access that Operates as a Rateless Code
Various applications of wireless Machine-to-Machine (M2M) communications have
rekindled the research interest in random access protocols, suitable to support
a large number of connected devices. Slotted ALOHA and its derivatives
represent a simple solution for distributed random access in wireless networks.
Recently, a framed version of slotted ALOHA gained renewed interest due to the
incorporation of successive interference cancellation (SIC) in the scheme,
which resulted in substantially higher throughputs. Based on similar principles
and inspired by the rateless coding paradigm, a frameless approach for
distributed random access in slotted ALOHA framework is described in this
paper. The proposed approach shares an operational analogy with rateless
coding, expressed both through the user access strategy and the adaptive length
of the contention period, with the objective to end the contention when the
instantaneous throughput is maximized. The paper presents the related analysis,
providing heuristic criteria for terminating the contention period and showing
that very high throughputs can be achieved, even for a low number for
contending users. The demonstrated results potentially have more direct
practical implications compared to the approaches for coded random access that
lead to high throughputs only asymptotically.Comment: Revised version submitted to IEEE Transactions on Communication
Impact of Correlated Mobility on Delay-Throughput Performance in Mobile Ad-Hoc Networks
AbstractâWe extend the analysis of the scaling laws of wireless ad hoc networks to the case of correlated nodes movements, which are commonly found in real mobility processes. We consider a simple version of the Reference Point Group Mobility model, in which nodes belonging to the same group are constrained to lie in a disc area, whose center moves uniformly across the network according to the i.i.d. model. We assume fast mobility conditions, and take as primary goal the maximization of pernode throughput. We discover that correlated node movements have huge impact on asymptotic throughput and delay, and can sometimes lead to better performance than the one achievable under independent nodes movements. I. INTRODUCTION AND RELATED WORK In the last few years the store-carry-forward communication paradigm, which allows nodes to physically carry buffered dat
Exploiting the Capture Effect to Enhance RACH Performance in Cellular-Based M2M Communications
Cellular-based machine-to-machine (M2M) communication is expected to facilitate services for the Internet of Things (IoT). However, because cellular networks are designed for human users, they have some limitations. Random access channel (RACH) congestion caused by massive access from M2M devices is one of the biggest factors hindering cellular-based M2M services because the RACH congestion causes random access (RA) throughput degradation and connection failures to the devices. In this paper, we show the possibility exploiting the capture effects, which have been known to have a positive impact on the wireless network system, on RA procedure for improving the RA performance of M2M devices. For this purpose, we analyze an RA procedure using a capture model. Through this analysis, we examine the effects of capture on RA performance and propose an Msg3 power-ramping (Msg3 PR) scheme to increase the capture probability (thereby increasing the RA success probability) even when severe RACH congestion problem occurs. The proposed analysis models are validated using simulations. The results show that the proposed scheme, with proper parameters, further improves the RA throughput and reduces the connection failure probability, by slightly increasing the energy consumption. Finally, we demonstrate the effects of coexistence with other RA-related schemes through simulation results
Random Access in DVB-RCS2: Design and Dynamic Control for Congestion Avoidance
In the current DVB generation, satellite terminals are expected to be
interactive and capable of transmission in the return channel with satisfying
quality. Considering the bursty nature of their traffic and the long
propagation delay, the use of a random access technique is a viable solution
for such a Medium Access Control (MAC) scenario. In this paper, random access
communication design in DVB-RCS2 is considered with particular regard to the
recently introduced Contention Resolution Diversity Slotted Aloha (CRDSA)
technique. This paper presents a model for design and tackles some issues on
performance evaluation of the system by giving intuitive and effective tools.
Moreover, dynamic control procedures that are able to avoid congestion at the
gateway are introduced. Results show the advantages brought by CRDSA to
DVB-RCS2 with regard to the previous state of the art.Comment: Accepted for publication: IEEE Transactions on Broadcasting; IEEE
Transactions on Broadcasting, 201
Design of Wireless Communication Networks for Cyber-Physical Systems with Application to Smart Grid
Cyber-Physical Systems (CPS) are the next generation of engineered systems in which computing, communication, and control technologies are tightly integrated. On one hand, CPS are generally large with components spatially distributed in physical world that has lots of dynamics; on the other hand, CPS are connected, and must be robust and responsive. Smart electric grid, smart transportation system are examples of emerging CPS that have significant and far-reaching impact on our daily life.
In this dissertation, we design wireless communication system for CPS. To make CPS robust and responsive, it is critical to have a communication subsystem that is reliable, adaptive, and scalable. Our design uses a layered structure, which includes physical layer, multiple access layer, network layer, and application layer. Emphases are placed on multiple access and network layer. At multiple access layer, we have designed three approaches, namely compressed multiple access, sample-contention multiple access, and prioritized multiple access, for reliable and selective multiple access. At network layer, we focus on the problem of creating reliable route, with service interruption anticipated. We propose two methods: the first method is a centralized one that creates backup path around zones posing high interruption risk; the other method is a distributed one that utilizes Ant Colony Optimization (ACO) and positive feedback, and is able to update multipath dynamically. Applications are treated as subscribers to the data service provided by the communication system. Their data quality requirements and Quality of Service (QoS) feedback are incorporated into cross-layer optimization in our design. We have evaluated our design through both simulation and testbed. Our design demonstrates desired reliability, scalability and timeliness in data transmission. Performance gain is observed over conventional approaches as such random access
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