1,585 research outputs found
A concatenated coded modulation scheme for error control
A concatenated coded modulation scheme for error control in data communications is presented. The scheme is achieved by concatenating a Reed-Solomon outer code and a bandwidth efficient block inner code for M-ary PSK modulation. Error performance of the scheme is analyzed for an AWGN channel. It is shown that extremely high reliability can be attained by using a simple M-ary PSK modulation inner code and relatively powerful Reed-Solomon outer code. Furthermore, if an inner code of high effective rate is used, the bandwidth expansion required by the scheme due to coding will be greatly reduced. The proposed scheme is particularly effective for high speed satellite communication for large file transfer where high reliability is required. Also presented is a simple method for constructing block codes for M-ary PSK modulation. Some short M-ary PSK codes with good minimum squared Euclidean distance are constructed. These codes have trellis structure and hence can be decoded with a soft decision Viterbi decoding algorithm
Near-Capacity Turbo Coded Soft-decision Aided DAPSK/Star-QAM
Low-complexity non-coherently detected Differential Amplitude and Phase-Shift Keying (DAPSK) schemes constitute an ideal candidate for wireless communications. In this paper, we derive the soft-output probability formulas required for the soft-decision based demodulation of DAPSK, which are then invoked for Turbo Coded (TC) transmissions. Furthermore, the achievable throughput characteristics of the family of M-ary DAPSK schemes are provided. It is shown that the proposed 4-ring based TC assisted 64-ary DAPSK scheme achieves a coding gain of about 4.2 dBs in comparison to the identical-throughput TC assisted 64-ary Differential Phase-Shift Keying (64-DPSK) scheme at a bit error ratio of 10?5
A concatenated coded modulation scheme for error control
A concatenated coded modulation scheme for error control in data communications is presented. The scheme is achieved by concatenating a Reed-Solomon outer code and a bandwidth efficient block inner code for M-ary PSK modulation. Error performance of the scheme is analyzed for an AWGN channel. It is shown that extremely high reliability can be attained by using a simple M-ary PSK modulation inner code and a relatively powerful Reed-Solomon outer code. Furthermore, if an inner code of high effective rate is used, the bandwidth expansion required by the scheme due to coding will be greatly reduced. The proposed scheme is very effective for high speed satellite communications for large file transfer where high reliability is required. A simple method is also presented for constructing codes for M-ary PSK modulation. Some short M-ary PSK codes with good minimum squared Euclidean distance are constructed. These codes have trellis structure and hence can be decoded with a soft decision Viterbi decoding algorithm. Furthermore, some of these codes are phase invariant under multiples of 45 deg rotation
Symmetric M-ary phase discrimination using quantum-optical probe states
We present a theoretical study of minimum error probability discrimination,
using quantum- optical probe states, of M optical phase shifts situated
symmetrically on the unit circle. We assume ideal lossless conditions and full
freedom for implementing quantum measurements and for probe state selection,
subject only to a constraint on the average energy, i.e., photon number. In
particular, the probe state is allowed to have any number of signal and
ancillary modes, and to be pure or mixed. Our results are based on a simple
criterion that partitions the set of pure probe states into equivalence classes
with the same error probability performance. Under an energy constraint, we
find the explicit form of the state that minimizes the error probability. This
state is an unentangled but nonclassical single-mode state. The error
performance of the optimal state is compared with several standard states in
quantum optics. We also show that discrimination with zero error is possible
only beyond a threshold energy of (M - 1)/2. For the M = 2 case, we show that
the optimum performance is readily demonstrable with current technology. While
transmission loss and detector inefficiencies lead to a nonzero erasure
probability, the error rate conditional on no erasure is shown to remain the
same as the optimal lossless error rate.Comment: 13 pages, 10 figure
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