Decode input using a sphere decoder
This block decodes the symbols sent over
using the sphere decoding algorithm.
For information about the data types each block port supports, see the Supported Data Type table on this page. The output signal inherits the data type from the inputs.
This block implements the algorithm, inputs, and outputs described
comm.SphereDecoder System object™ block
reference page. The object properties correspond to the block parameters.
Specify the number of points in the signal constellation to which the bits are mapped. This value must be a complex column vector. The length of the vector must be a power of two. The block uses the same constellation for each transmit antenna. The default setting is a QPSK constellation with an average power of 1.
Specify the bit mapping that the block uses for each constellation point. This value must be a numerical matrix. he matrix size must be [ConstellationLength bitsPerSymbol], where ConstellationLength represents the length of the Signal constellation parameter value and bitsPerSymbol represents the number of bits that each symbol encodes. The default matrix size is [0 0; 0 1; 1 0; 1 1], which matches the default value of the Signal constellation property.
Specify the initial search radius for the decoding algorithm
When you select
Infinity, the block
sets the initial search radius to Inf. When you select
solution, the block 'sets the initial search radius
to the zero-forcing solution. The zero-forcing solution is calculated
by the pseudo-inverse of the input channel when decoding. Large constellations
and/or antenna counts can benefit from the initial reduction in the
search radius. In most cases, however, the extra computation of the
Solution will not provide a benefit.
Specify the decoding decision method as
When you select
Soft the block outputs
log-likelihood ratios (LLRs), or soft bits. When you select set to
the block converts the soft LLRs to bits. The hard decision output
logical array follows the mapping of a
0 for a
negative LLR and
1 for all other values.
Specify if the block simulates using
Code generation or
execution. The default is
This block implements the algorithm, inputs, and outputs described on the Sphere Decoder System object reference page. The object properties correspond to the block parameters.
|Port||Supported Data Types|
The output LLR values are not scaled by the noise variance. For coded links employing iterative coding (LDPC or turbo) or MIMO OFDM with Viterbi decoding, the output LLR values should be scaled by the channel state information to achieve better performance.