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ABSTRACT: Cooperative Networking is a new technology which exploits the massive deployment of nodes in wireless sensor networks. Cooperative Networking synergistically integrates Networking with cluster-based Cooperative Communications to improve reliability and enhance network performance. In this paper, we consider the effect of link-level feedback and retransmissions on the performance of wireless sensor networks using Cooperative Networking, and we present scenarios where link-level retransmission offers a significant improvement in network throughput. Generally, Cooperative Networking with link-level retransmission provides higher throughput when the network node density is low (i.e., sparse networks) or in environments with adverse conditions such as high probability of transmission loss and low connectivity among the nodes.
Wireless Communications and Networking Conference (WCNC), 2011 IEEE; 05/2011
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Communications, IEEE Transactions on. 01/2002; 42(234):1740-1751.
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ABSTRACT: The time-frequency-code slicing technique allows multiple users
with different data-rate requirements access to a communications
resource in a manner that is cost effective over a wide range of access
rates. For Instance, with a time-frequency slicing (TFS) approach, users
are assigned different portions of the frequency spectrum (e.g., on a
slot-by-slot basis), granting them access to a fraction of the shared
resource that is commensurate with their needs and their own end
equipment. Users with high-data-rate requirements can “grab all
the band-width” when no one else needs it. Also, by efficiently
packing the time-frequency space, better system utilization is attained.
For the specific case of TFS, we compute the reduction in blocking
probability achieved under the constraint of a single
transmitter/receiver per user. As an example, consider the case of 70%
traffic load with ten frequency bands and 15 time slots per frame. Using
the traditional allocation scheme in which users can be assigned only a
single-frequency band per time slot, there is a 10% blocking probability
for new connections that request 14 “time-frequency slices”.
The TFS technique reduces this blocking probability to well below 0.01%
IEEE Transactions on Vehicular Technology 12/1997; · 1.92 Impact Factor
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ABSTRACT: The increased demand for wireless mobile communications coupled
with the finite available spectrum has motivated investigation into
alternative methods of tracking users and delivering calls. We present a
new scheme for delivering mobile terminated calls named reverse virtual
call setup (RVC). Only a few new fixed network SS7 signaling messages
are needed to implement this protocol; we specify them here. RVC can
function within the existing cellular paging network or with an
integrated overlaid paging network. The relative performance of RVC for
both scenarios is investigated
IEEE/ACM Transactions on Networking 03/1997; · 2.03 Impact Factor
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ABSTRACT: In broadband networks, it is expected that at a given time there will be more data in the network than in narrowband networks, and therefore, to maintain the same quality of service, failures will need to be restored much faster. The purpose of this article is to demonstrate that broadband network technology, and in particular the asynchronous transfer mode (ATM), has factors that enable much faster restoration in broadband networks. These can be summarized as: (i) the higher-speed processing and larger-volume storage possible with today's technology as compared to what was available for narrowband networks, (ii) faster failure detection by making use of ATM cell header error checks, (iii) easier and faster rerouting simply by changing cell headers, (iv) easier and faster splitting of virtual paths by changing cell headers, (v) higher fill factors in the new digital hierarchy due to full termination at cross-connects and switches, and (vi) the statistical multiplexing advantage that can be exploited in a full ATM network configuration. The authors describe four basic characteristics of broadband network restoration, made faster and more efficient because of the factors listed above. These are (i) hitless protection switching, (ii) robust and fast failure detection, (iii) restoration alternatives in broadband networks, and (iv) fast topology update for multiple failures. By employing a combination of these methods, fast restoration of broadband networks can be achieved. The techniques described enable a B-ISDN/ATM network to be constructed that is highly self-healing (i.e., can recover from failures without human intervention) and very fast.
IEEE Communications Magazine 08/1996; · 3.79 Impact Factor
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ABSTRACT: The increased demand for wireless PCS communications coupled with
limited spectrum has motivated many to investigate techniques that
minimize the radio link traffic needed to deliver calls to users and to
track their locations. As the location area increases, the paging cost
increases and the registration cost decreases. Previous work minimized
the radio link traffic in a single cell along the perimeter of a
location area. In this paper, we minimize the total radio bandwidth
traffic throughout the entire system. This approach results in a larger
location area. This will reduce the fixed network signaling load. This
paper also briefly describes a new scheme for delivering mobile
terminated calls called the reverse virtual call setup (RVC) algorithm.
We evaluate the radio link cost when a separate overlaid paging system
is used in conjunction with RVC. It is shown to be relatively
insensitive to location area size over a large range of practical
parameters. Results indicate that the location area size should be as
large as the restrictions of finite bandwidth and power permit. A
one-to-one relationship between a mobile switching center (MSC) and a
location area is shown to be a good solution
Vehicular Technology Conference, 1995 IEEE 45th; 08/1995
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ABSTRACT: Multi-code CDMA (MC-CDMA) was proposed as a technique to provide
variable rate services with different quality requirements by varying
the number of codes assigned to a user. When all other users are idle, a
single user is able to use the full bit rate available in that cell. The
system retains the CDMA advantage in combating multipath and does not
require significant modifications of the radio frequency (RF) circuitry.
It can evolve from commercial digital cellular systems based on IS-95.
The paper presents preliminary results on the performance of MC-CDMA.
The authors consider both voice and data users. Voice users are delay
sensitive whereas the authors assume that data users can tolerate delay
but require a lower bit error rate. They evaluate the instantaneous
capacity as well as the average capacity which accounts for user
activity factors and the control channel overhead needed for inactive
users to maintain synchronization. Unrestricted access to the channel is
given to voice bursts. Data bursts are required to wait until they are
permitted to transmit. The authors show that the multi-code capability
significantly improves the delay throughput performance of data users
Vehicular Technology Conference, 1995 IEEE 45th; 08/1995
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ABSTRACT: Proposes a code division multiple access (CDMA) based system that
can provide a smooth migration path to PCS, either from a digital
cellular system (IS-95) or from a wideband CDMA system, to serve both
isochronous and asynchronous applications. A unified digital bandwidth
on demand platform is realized by allocating multiple codes (on demand),
and hence increased capacity, to users. This approach, dubbed multi-code
CDMA (MC-CDMA), will enable efficient delivery of all services made
possible by digital cellular, CDPD, and other PCS technologies. Since a
large variety of services (voice, data, image, and perhaps video) is
expected in future wireless networks, users with very different, and
time-varying, source rates will have to be accommodated. MC-CDMA is a
wireless system whose rate (which is proportional to the number of codes
assigned to the user) and service are dynamically matched to users'
needs and can evolve from commercial digital cellular systems. This
system retains the CDMA advantage in combating multipath and does not
require significant modifications of the radio frequency (RF) circuitry.
The dynamic, packet-like capacity access enabled by MC-CDMA will allow
users to access the base station at different source rates, and when all
other users are idle, will provide peak rate access to a single user
Communications, 1995. ICC '95 Seattle, 'Gateway to Globalization', 1995 IEEE International Conference on; 07/1995
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ABSTRACT: The increased demand for wireless mobile communications coupled
with the finite available spectrum has motivated investigation into
alternative methods of tracking users and delivering calls. We present a
new scheme for delivering mobile terminated calls called reverse virtual
call setup (RVC) and discuss its performance using the metrics of fixed
network cost, and call setup delay. New MAP messages needed to implement
the RVC protocol are specified . We identify the conditions under which
the fixed network signaling system loading and call setup delay are
reduced. In particular we show that the performance improvement over the
conventional strategy depends upon the degree of resolution that the
system must track a user's location
Communications, 1995. ICC '95 Seattle, 'Gateway to Globalization', 1995 IEEE International Conference on; 07/1995
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ABSTRACT: Describes the design, validation, implementation and performance
of an asymmetric link-layer protocol for a wireless link. The motivation
for designing a new link-layer protocol is to obtain better performance
in terms of end-to-end throughput and latency by correcting errors in an
unreliable wireless link in addition to end-to-end correction rather
than by correcting errors only by end-to-end retransmissions. The
protocol described concentrates on asymmetry, although the concept of
adaptive forward error correction is briefly introduced. The protocol
also supports mobility. The asymmetry is needed in the design because
the wireless terminals have limited power and smaller processing
capability than the base stations. The key ideas in the design consist
of placing the bulk of the intelligence in the base station as opposed
to placing it symmetrically, in requiring the wireless terminal to
combine several acknowledgments into a single acknowledgment to conserve
power, and in designing the base stations to send periodic status
messages, while making the acknowledgment from the wireless terminal
event driven. The asymmetry in the protocol design results in a
one-third reduction of the compiled code and a two-thirds reduction of
processing overhead in the wireless terminal. Some performance results
are also presented
INFOCOM '95. Fourteenth Annual Joint Conference of the IEEE Computer and Communications Societies. Bringing Information to People. Proceedings. IEEE; 05/1995
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ABSTRACT: The transition to B-ISDN from current networks represents a major technological discontinuity for the communications world. These discontinuities must be considered for the successful evolution of existing networks to broadband networks. The authors provide an overview of B-ISDN data transfer protocols and the services it will support. They discuss the effects of B-ISDN switching, network operations and management, signalling protocols and architectures, and networked computing.< >
IEEE Communications Magazine 11/1994; · 3.79 Impact Factor
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ABSTRACT: We propose a time-frequency-code-slicing technique that allows
multiple users with different speed requirements access to a
communications resource in a manner that is cost effective over a wide
range of access speeds. Conventional systems require low-speed users to
either pay a cost premium (e.g., high-speed burst modems for TDMA) or
end up wasting some of the spectrum (e.g., universal time slots). The
advantages of our proposed scheme can be demonstrated with any two
combinations (or all three) of time slicing, frequency slicing, and code
slicing. For instance, with a time-frequency-slicing approach, users can
be assigned different portions of the spectrum (e.g., on a slot-by-slot
basis), allowing them access to only the needed fraction of the shared
resource. With time-code slicing, users are dynamically granted portions
of the code space, during specified time periods. Finally, in
frequency-code slicing, a user may be assigned a number of codes in
different frequency bands. These codes can be of constant or variable
chip rates
Personal, Indoor and Mobile Radio Communications, 1994. Wireless Networks - Catching the Mobile Future., 5th IEEE International Symposium on; 10/1994
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IEEE Communications Magazine. 10/1994;
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ABSTRACT: For a broad class of interference-dominated wireless systems
including mobile, personal communications, and wireless PBX/LAN
networks, the authors show that a significant increase in system
capacity can be achieved by the use of spatial diversity (multiple
antennas), and optimum combining. This is explained by the following
observation: for independent flat-Rayleigh fading wireless systems with
N mutually interfering users, they demonstrate that with K+N antennas,
N-1 interferers can be nulled out and K+1 path diversity improvement can
be achieved by each of the N users. Monte Carlo evaluations show that
these results also hold with frequency-selective fading when optimum
equalization is used at the receiver. Thus an N-fold increase in user
capacity can be achieved, allowing for modular growth and improved
performance by increasing the number of antennas. The interferers can
also be users in other cells, users in other radio systems, or even
other types of radiating devices, and thus interference cancellation
also allows radio systems to operate in high interference environments.
As an example of the potential system gain, the authors show that with 2
or 3 antennas the capacity of the mobile radio system IS-54 can be
doubled, and with 5 antennas a 7-fold capacity increase (frequency reuse
in every cell) can be achieved
IEEE Transactions on Communications 03/1994; · 1.68 Impact Factor
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ABSTRACT: pg 100 diversity coding, as introduced in Ayanoglu et al. (1990),
is a method of protection against failures in a communication network or
a storage system, which is based on introducing a digital
error-correcting code across independent links. This technique makes
efficient use of the extra network capacity needed for coding and has
the additional advantages of being nearly instantaneous, not requiring a
feedback channel, rerouting, or resynchronization. In high-speed (multi
Gbps) networks, digital coding will be difficult to implement, and the
purpose of the present paper is to demonstrate how diversity coding may
be implemented in the analog domain using the discrete fourier transform
(DFT). In particular, the authors show that the DFT is a
continuous-amplitude maximum-distance separable code over the field of
complex numbers when the transform kernel is a prime root of unity. This
code can be used to generate self-healing or fault-tolerant
communication networks for continuous- or discrete-amplitude signals, as
long as continuous-amplitude parity channels are available. The authors
describe electrical and optoelectronic implementations, and a signal
estimation approach to combat channel noise and thereby improve the
performance of the analog diversity coding system. The most important
advantage of this technique is in greatly simplifying the encoders and
decoders of diversity coding systems for high-speed networks, such as
fiber-optic wavelength division multiplexed networks. Application of
analog diversity coding to systems with analog sources, such as
telemetry systems is also possible
IEEE Transactions on Communications 02/1994; · 1.68 Impact Factor
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ABSTRACT: A channel coding approach called diversity coding is introduced
for self-healing and fault-tolerance in digital communication networks
for nearly instantaneous recovery from link failures. To achieve this
goal, the problem of link failures is treated as an erasure channel
problem. Implementation details of this technique in existing and future
communication networks are discussed
IEEE Transactions on Communications 12/1993; · 1.68 Impact Factor
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ABSTRACT: Th authors explore the use of a wireless network having a two-tier
architecture to serve both conventional mobile subscribers and
quasi-stationary (e.g., PCN (personal communications network))
subscribers. The latter are served by microcells which are embedded
within macrocells that serve the mobile users. This provides a balance
between maximizing the number of users per unit area (which favors small
cells) and minimizing the network control associated with handoff (which
favors large cells). Four approaches to sharing the spectrum between the
two tiers, using per-cell capacity as the measure, are evaluated. The
first two feature spread-spectrum sharing, i.e., they use TDMA
(time-division multiple access) among microcell users and CDMA
(code-division multiple access) among macrocell users (System I), or
vice versa (System II). The other two approaches feature orthogonal
sharing, i.e., they use TDMA in both tiers, with time slots (System III)
or frequency channels (System IV) partitioned so there is no overlap
between tiers. Analysis shows that the capacity tradeoffs are poor for
Systems I and II because of the large amounts of cross-tier
interference: and that System IV gives the best capacity tradeoffs
IEEE Journal on Selected Areas in Communications 09/1993; · 3.41 Impact Factor
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ABSTRACT: The major impairments in lightwave systems and the signal-processing techniques that can be used to reduce these impairments are discussed. Guidelines for the use of these techniques are presented. These guidelines are used to determine the techniques with the most potential for providing improved performance in long-haul systems, local-area networks, and local loop systems. Although many of the techniques have been previously considered for these applications, few have been implemented in commercial products. Some of the most promising techniques include dispersion-compensating fibers, polarization control, nonlinear cancellation (NLC), and coding for reducing the effect of distortion in long-haul single-frequency-laser direct-detection systems.< >
IEEE Communications Magazine 07/1993; · 3.79 Impact Factor
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ABSTRACT: The use of two resource-sharing techniques for congestion control
in a backbone asynchronous transfer mode (ATM) network consisting of ATM
cross-connects interconnected with high-speed optical links such as
2.4-Gb/s OC-48c fibers is studied. Memory sharing allows an optimal
shared use of buffer space in an ATM switch fabric. Channel (or line)
sharing, on the other hand, takes advantage of spare line capacity in
the system to permit temporary increases in the output rates of the
congested output ports. Fundamental bounds on delay-throughput
performance and buffer requirements for specific cell loss rates are
presented, and two practical application scenarios, representing line
protection arrangements with and without service access capabilities,
are introduced
INFOCOM '93. Proceedings.Twelfth Annual Joint Conference of the IEEE Computer and Communications Societies. Networking: Foundation for the Future. IEEE; 02/1993
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Adaptive Antenna Systems Symposium, 1992., Proceedings of the IEEE Long Island Section; 12/1992
