Nonlinear Equalization NLEQ of RF Receivers HPCEnabled Search for a NearOptimal NLEQ Architecture Be

1
Nonlinear Equalization (NLEQ) of RF
ReceiversHPC-Enabled Search for a Near-Optimal
NLEQ ArchitectureBenjamin Miller1, Gil Raz2,
Brandon Kam1, Joel Goodman1/ 1MIT Lincoln
Laboratory, 2GMR Research Technology, Inc.
Method
Objective
Greedy Search Algorithm 1) Find the PE that
equalizes best with the current NLEQ
architecture 2) Add this PE to the
architecture 3) Repeat until there are N
PEs in the architecture
Lowest MSE
NLEQ
PE1
PEi
PEM
n2
NLEQ
NLEQ
PEi
n1
The Partitioned Horizontal Coordinate System
(PHoCS) is a pruned version of the highly
over-parameterized Volterra kernel.
n3
Full Volterra
The objective of Nonlinear Equalization (NLEQ) is
to extend the dynamic range of RF receivers by
reducing in-band nonlinear distortions. This
enables detection of weak targets otherwise
masked by distortions present after digital
integration.
Globally Optimal PHoCS
Locally Optimal PHoCS
Even with these improvements, a typical
experiment requires over 5x1014 operations!
LLGrid
NLEQ Architecture Search Procedure
Cluster Switch
Compute Nodes
Service Nodes
Identify architecture using the greedy algorithm
Network Storage
Resource Manager
Jobs partitioned usingMatlabMPI
Construct frequency- domain database of
multi-tonal signals
ConfigurationServer
Verify performance of identified architecture
To LincolnLAN
LAN Switch
Results
As illustrated in the chart above, the goal of
NLEQ is to increase the intermod-free dynamic
range of the analog-to-digital converter (ADC)
decades beyond the state-the-art.
NLEQ improves wideband ADC dynamic range by up to
27 dB, a 27-year improvement!
With parallelization, experiments take days
rather than months
MEASURED results with MAX108 ADC at 1.5 GSPS,
500MHz instantaneous bandwidth
This work is sponsored by the Defense Advanced
Research Projects Administration under Air Force
Contract FA8721-05-C-0002. Opinions,
interpretations, conclusions, and recommendations
are those of the authors and are not necessarily
endorsed by the United States Government