371,849 research outputs found
All-to-all Broadcast for Vehicular Networks Based on Coded Slotted ALOHA
We propose an uncoordinated all-to-all broadcast protocol for periodic
messages in vehicular networks based on coded slotted ALOHA (CSA). Unlike
classical CSA, each user acts as both transmitter and receiver in a half-duplex
mode. As in CSA, each user transmits its packet several times. The half-duplex
mode gives rise to an interesting design trade-off: the more the 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 compare the proposed protocol with carrier sense multiple access
with collision avoidance, currently adopted as a multiple access protocol for
vehicular networks. The results show that the proposed protocol greatly
increases the number of users in the network that reliably communicate with
each other. We also provide analytical tools to predict the performance of the
proposed protocol.Comment: v2: small typos fixe
Protocol Design and Stability Analysis of Cooperative Cognitive Radio Users
A single cognitive radio transmitter--receiver pair shares the spectrum with
two primary users communicating with their respective receivers. Each primary
user has a local traffic queue, whereas the cognitive user has three queues;
one storing its own traffic while the other two are relaying queues used to
store primary relayed packets admitted from the two primary users. A new
cooperative cognitive medium access control protocol for the described network
is proposed, where the cognitive user exploits the idle periods of the primary
spectrum bands. Traffic arrival to each relaying queue is controlled using a
tuneable admittance factor, while relaying queues service scheduling is
controlled via channel access probabilities assigned to each queue based on the
band of operation. The stability region of the proposed protocol is
characterized shedding light on its maximum expected throughput. Numerical
results demonstrate the performance gains of the proposed cooperative cognitive
protocol.Comment: Accepted in WCNC 201
Cross-layer scheduling and resource allocation for heterogeneous traffic in 3G LTE
3G long term evolution (LTE) introduces stringent needs in order to provide different kinds of traffic with Quality of Service (QoS) characteristics. The major problem with this nature of LTE is that it does not have any paradigm scheduling algorithm that will ideally control the assignment of resources which in turn will improve the user satisfaction. This has become an open subject and different scheduling algorithms have been proposed which are quite challenging and complex. To address this issue, in this paper, we investigate how our proposed algorithm improves the user satisfaction for heterogeneous traffic, that is, best-effort traffic such as file transfer protocol (FTP) and real-time traffic such as voice over internet protocol (VoIP). Our proposed algorithm is formulated using the cross-layer technique. The goal of our proposed algorithm is to maximize the expected total user satisfaction (total-utility) under different constraints. We compared our proposed algorithm with proportional fair (PF), exponential proportional fair (EXP-PF), and U-delay. Using simulations, our proposed algorithm improved the performance of real-time traffic based on throughput, VoIP delay, and VoIP packet loss ratio metrics while PF improved the performance of best-effort traffic based on FTP traffic received, FTP packet loss ratio, and FTP throughput metrics
Formal Verification of Safety Properties for Ownership Authentication Transfer Protocol
In ubiquitous computing devices, users tend to store some valuable
information in their device. Even though the device can be borrowed by the
other user temporarily, it is not safe for any user to borrow or lend the
device as it may cause private data of the user to be public. To safeguard the
user data and also to preserve user privacy we propose and model the technique
of ownership authentication transfer. The user who is willing to sell the
device has to transfer the ownership of the device under sale. Once the device
is sold and the ownership has been transferred, the old owner will not be able
to use that device at any cost. Either of the users will not be able to use the
device if the process of ownership has not been carried out properly. This also
takes care of the scenario when the device has been stolen or lost, avoiding
the impersonation attack. The aim of this paper is to model basic process of
proposed ownership authentication transfer protocol and check its safety
properties by representing it using CSP and model checking approach. For model
checking we have used a symbolic model checker tool called NuSMV. The safety
properties of ownership transfer protocol has been modeled in terms of CTL
specification and it is observed that the system satisfies all the protocol
constraint and is safe to be deployed.Comment: 16 pages, 7 figures,Submitted to ADCOM 201
A-MAKE: an efficient, anonymous and accountable authentication framework for WMNs
In this paper, we propose a framework, named as A-MAKE, which efficiently provides security, privacy, and accountability for communications in wireless mesh networks. More specifically, the framework provides an anonymous mutual authentication protocol whereby legitimate users can connect to network from anywhere without being identified or tracked. No single party (e.g., network operator) can violate the privacy of a user, which is provided in our framework in the strongest sense. Our framework utilizes group signatures, where the private key and the credentials of the users are generated through a secure three-party protocol. User accountability is implemented via user revocation protocol that can be executed by two semitrusted authorities, one of which is the network operator. The assumptions about the trust level of the network operator are relaxed. Our framework makes use of much more efficient signature generation and verification algorithms in terms of computation complexity than their counterparts in literature, where signature size is comparable to the shortest signatures proposed for similar purposes so far
Novel Subcarrier-pair based Opportunistic DF Protocol for Cooperative Downlink OFDMA
A novel subcarrier-pair based opportunistic DF protocol is proposed for
cooperative downlink OFDMA transmission aided by a decode-and-forward (DF)
relay. Specifically, user message bits are transmitted in two consecutive
equal-duration time slots. A subcarrier in the first slot can be paired with a
subcarrier in the second slot for the DF relay-aided transmission to a user. In
particular, the source and the relay can transmit simultaneously to implement
beamforming at the subcarrier in the second slot for the relay-aided
transmission. Each unpaired subcarrier in either the first or second slot is
used by the source for direct transmission to a user without the relay's
assistance. The sum rate maximized resource allocation (RA) problem is
addressed for this protocol under a total power constraint. It is shown that
the novel protocol leads to a maximum sum rate greater than or equal to that
for a benchmark one, which does not allow the source to implement beamforming
at the subcarrier in the second slot for the relay-aided transmission. Then, a
polynomial-complexity RA algorithm is developed to find an (at least
approximately) optimum resource allocation (i.e., source/relay power,
subcarrier pairing and assignment to users) for either the proposed or
benchmark protocol. Numerical experiments illustrate that the novel protocol
can lead to a much greater sum rate than the benchmark one.Comment: 6 pages, accepted by 2013 IEEE Wireless Communications and Networking
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