225,503 research outputs found
Acknowledgement of priority - A fractional Helly theorem for boxes
In our recent paper [1] we prove a fractional Helly type theorem for boxes in Rd. This short note is to acknowledge
priority: in 1980 Meir Katchalski [4] proved exactly the same result and in 1988 Jürgen Eckhoff [2] proved the same result
in much more generality. In fact, Eckhoff established an upper bound theorem for the f -vectors of finite families of boxes
in Rd from which his result is derived. Besides apologies for our ignorance we would like to mention that Eckhoff extended
his results further in a more recent paper [3]
On the Stability of Random Multiple Access with Feedback Exploitation and Queue Priority
In this paper, we study the stability of two interacting queues under random
multiple access in which the queues leverage the feedback information. We
derive the stability region under random multiple access where one of the two
queues exploits the feedback information and backs off under negative
acknowledgement (NACK) and the other, higher priority, queue will access the
channel with probability one. We characterize the stability region of this
feedback-based random access protocol and prove that this derived stability
region encloses the stability region of the conventional random access (RA)
scheme that does not exploit the feedback information
Pipeline AER arbitration with event aging
We present a simple circuit to handle communication between cells of neuromorphic arrays. It allows cells to operate continuously without waiting for acknowledgement signals back from the AER (Address Event Representation) arbitration circuitry. The module also implements aging of cell petitions i.e., old petitions to access to the AER bus are automatically discarded to give priority to the more recent ones and alleviate the bus congestion. The new arbitration scheme has been implemented and tested. A particular application scenario with an image sensor with spiking pixels that sense light continuously is explained. The sensing errors per event due to discontinued pixel operation can be minimized a factor 8.1. Experimental data obtained with real visual scenes are provided.Universidad de Cádiz PR2016-072Ministerio de Economía y Competitividad TEC2015-66878- C3-1-RJunta de Andalucía TIC 2012-2338Office of Naval Research (USA) N00014141035
Smart Acknowledgement Distributed Channel Access Scheme for TCP in MANETs
TCP upon wireless networks is most challenging issue because of random losses and ACK interference. Also, TCP suffers from performance declination in terms of creating delay and overhead in network because of poor characteristics of wireless channel. In order to overcome these issues, we proposed a Smart Acknowledgement Distributed Channel Access (SADCA) scheme for TCP in MANETs. In the proposed scheme, first a separate Access Category (AC) for data less TCP acknowledgement packets is used and then it is assigned with highest priority. In this way, delay during transmission of packet can be reduced and also packet can be acknowledged immediately. Also, to increase the performance, delay window size can be adjusted by considering the parameters such as transmission rate, number of hops, and channel occupied ratio (COR). Hence the proposed scheme helps to avoid any kind of delay and overhead for sending TCP acknowledgemen
Distributed Channel Access for Control Over Known and Unknown Gilbert-Elliott Channels
We consider the distributed channel access problem for a system consisting of multiple control subsystems that close their loop over a shared wireless network with multiple channels subject to Markovian packet dropouts. Provided that an acknowledgement/negative-acknowledgement feedback mechanism is in place, we show that this problem can be formulated as a Markov decision process. We then transform this problem to a form that enables distributed control-aware channel access. More specifically, we show that the control objective can be minimized without requiring information exchange between subsystems as long as the channel parameters are known. The objective is attained by adopting a priority-based deterministic channel access method and the stability of the system under the resulting scheme is analyzed. Next, we consider a practical scenario in which the channel parameters are unknown and adopt a learning method based on Bayesian inference which is compatible with distributed implementation. We propose a heuristic posterior sampling algorithm which is shown to significantly improve performance via simulations
Adjacency Matrix Based Energy Efficient Scheduling using S-MAC Protocol in Wireless Sensor Networks
Communication is the main motive in any Networks whether it is Wireless
Sensor Network, Ad-Hoc networks, Mobile Networks, Wired Networks, Local Area
Network, Metropolitan Area Network, Wireless Area Network etc, hence it must be
energy efficient. The main parameters for energy efficient communication are
maximizing network lifetime, saving energy at the different nodes, sending the
packets in minimum time delay, higher throughput etc. This paper focuses mainly
on the energy efficient communication with the help of Adjacency Matrix in the
Wireless Sensor Networks. The energy efficient scheduling can be done by
putting the idle node in to sleep node so energy at the idle node can be saved.
The proposed model in this paper first forms the adjacency matrix and
broadcasts the information about the total number of existing nodes with depths
to the other nodes in the same cluster from controller node. When every node
receives the node information about the other nodes for same cluster they
communicate based on the shortest depths and schedules the idle node in to
sleep mode for a specific time threshold so energy at the idle nodes can be
saved.Comment: 20 pages, 2 figures, 14 tables, 5 equations, International Journal of
Computer Networks & Communications (IJCNC),March 2012, Volume 4, No. 2, March
201
Split, Send, Reassemble: A Formal Specification of a CAN Bus Protocol Stack
We present a formal model for a fragmentation and a reassembly protocol
running on top of the standardised CAN bus, which is widely used in automotive
and aerospace applications. Although the CAN bus comes with an in-built
mechanism for prioritisation, we argue that this is not sufficient and provide
another protocol to overcome this shortcoming.Comment: In Proceedings MARS 2017, arXiv:1703.0581
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
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