1,712 research outputs found
Compressive Parameter Estimation for Sparse Translation-Invariant Signals Using Polar Interpolation
We propose new compressive parameter estimation algorithms that make use of
polar interpolation to improve the estimator precision. Our work extends
previous approaches involving polar interpolation for compressive parameter
estimation in two aspects: (i) we extend the formulation from real non-negative
amplitude parameters to arbitrary complex ones, and (ii) we allow for mismatch
between the manifold described by the parameters and its polar approximation.
To quantify the improvements afforded by the proposed extensions, we evaluate
six algorithms for estimation of parameters in sparse translation-invariant
signals, exemplified with the time delay estimation problem. The evaluation is
based on three performance metrics: estimator precision, sampling rate and
computational complexity. We use compressive sensing with all the algorithms to
lower the necessary sampling rate and show that it is still possible to attain
good estimation precision and keep the computational complexity low. Our
numerical experiments show that the proposed algorithms outperform existing
approaches that either leverage polynomial interpolation or are based on a
conversion to a frequency-estimation problem followed by a super-resolution
algorithm. The algorithms studied here provide various tradeoffs between
computational complexity, estimation precision, and necessary sampling rate.
The work shows that compressive sensing for the class of sparse
translation-invariant signals allows for a decrease in sampling rate and that
the use of polar interpolation increases the estimation precision.Comment: 13 pages, 5 figures, to appear in IEEE Transactions on Signal
Processing; minor edits and correction
Compressive Time Delay Estimation Using Interpolation
Time delay estimation has long been an active area of research. In this work,
we show that compressive sensing with interpolation may be used to achieve good
estimation precision while lowering the sampling frequency. We propose an
Interpolating Band-Excluded Orthogonal Matching Pursuit algorithm that uses one
of two interpolation functions to estimate the time delay parameter. The
numerical results show that interpolation improves estimation precision and
that compressive sensing provides an elegant tradeoff that may lower the
required sampling frequency while still attaining a desired estimation
performance.Comment: 5 pages, 2 figures, technical report supporting 1 page submission for
GlobalSIP 201
A framework for achieving organisational objectives through integrated performance management
M.Com. (Business Management
Compressive Sensing for Spread Spectrum Receivers
With the advent of ubiquitous computing there are two design parameters of
wireless communication devices that become very important power: efficiency and
production cost. Compressive sensing enables the receiver in such devices to
sample below the Shannon-Nyquist sampling rate, which may lead to a decrease in
the two design parameters. This paper investigates the use of Compressive
Sensing (CS) in a general Code Division Multiple Access (CDMA) receiver. We
show that when using spread spectrum codes in the signal domain, the CS
measurement matrix may be simplified. This measurement scheme, named
Compressive Spread Spectrum (CSS), allows for a simple, effective receiver
design. Furthermore, we numerically evaluate the proposed receiver in terms of
bit error rate under different signal to noise ratio conditions and compare it
with other receiver structures. These numerical experiments show that though
the bit error rate performance is degraded by the subsampling in the CS-enabled
receivers, this may be remedied by including quantization in the receiver
model. We also study the computational complexity of the proposed receiver
design under different sparsity and measurement ratios. Our work shows that it
is possible to subsample a CDMA signal using CSS and that in one example the
CSS receiver outperforms the classical receiver.Comment: 11 pages, 11 figures, 1 table, accepted for publication in IEEE
Transactions on Wireless Communication
Contesting the transition from apartheid to democracy in the workplace
Paper presented at the Wits History Workshop: Forging the links between historical research and the policy process, 18-19 September 1999. Paper drawn from the Author's thesis "Trade unions in the workplace and the community 1984-1994; a case study of a steel mill.This paper explores the contestation between Highveld Steel and NUMSA over the transition from the apartheid workplace regime during 1993-1995. NUMSA wanted a radical democratisation of the workplace and the company; enhancing worker control and skills. Management wanted to retain control and disempower the workers
Distributed Remote Vector Gaussian Source Coding for Wireless Acoustic Sensor Networks
In this paper, we consider the problem of remote vector Gaussian source
coding for a wireless acoustic sensor network. Each node receives messages from
multiple nodes in the network and decodes these messages using its own
measurement of the sound field as side information. The node's measurement and
the estimates of the source resulting from decoding the received messages are
then jointly encoded and transmitted to a neighboring node in the network. We
show that for this distributed source coding scenario, one can encode a
so-called conditional sufficient statistic of the sources instead of jointly
encoding multiple sources. We focus on the case where node measurements are in
form of noisy linearly mixed combinations of the sources and the acoustic
channel mixing matrices are invertible. For this problem, we derive the
rate-distortion function for vector Gaussian sources and under covariance
distortion constraints.Comment: 10 pages, to be presented at the IEEE DCC'1
From the politics of resistance to the politics of reconstruction: The union and 'ungovernability' in the workplace
African Studies Seminar series. Paper presented 22 September 1997South Africa has undergone momentous change over the past decade. The trade union
movement in the shape of COSATU has played a central role in that change. During the late
1980s it became the most organised and visible component of the internal mass democratic
movement. After 1990 it became the major alliance partner of the unbanned ANC.
On the one hand COSATU was an important advocate and organiser of the mass mobilisation
campaigns which kept up the momentum of national political negotiations. It was the
originator of the Reconstruction and Development Programme [RDP], later taken up by the
ANC as the core of its election and governmental programme. COSATU also provided much
of the organisation and the personnel for the ANC election campaign in 1994. At the same
time the trade unions were trying to develop new policies and new strategies appropriate to
the new conditions of a democratic - or democratising - society. The National Union of
Metalworkers of South Africa [NUMSA] was at the forefront of developing such policies,
focusing on reform of human resource policies and institutions, and on industrial strategy.
These developments have been characterised by labour movement analysts as a shift from
'social movement unionism' to 'strategic unionism' founded on a strategy of 'radical reform',
(see Joffe et al, 1992; Von Holdt, 1992b; Von Holdt and Webster, 1992
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