A New Differential Space-Time Modulation Scheme based on Weyl Group 11th International Symposium on Signals, Circuits and Systems (ISSCS 2013) 11 - 12, July, 2013, Iasi, Romania A New Differential Space-Time Modulation Scheme based on Weyl Group JI Hui, Gheorghe Zaharia and Jean-François Hélard Institute of Electronics and Telecommunications of Rennes (IETR) Institut National des Sciences Appliquées (INSA), France

Outline Differential Space-Time Modulation (DSTM) New scheme for MIMO systems Simulation and comparison Conclusions 1

Outline Differential Space-Time Modulation (DSTM) New scheme for MIMO systems Simulation and comparison Conclusions 1

Differential Space-Time Modulation Advantage: not require channel state information Used for MIMO systems with large number of antennas Used for MIMO systems when the propagation channel changes rapidly Existing differential space-time modulation schemes: Differential space-time block codes (DSTBC) Differential unitary space-time modulation (DUSTM) … 2

Differential Space-Time Modulation System model: Fundamental differential transmission relation: where is a unitary matrix which carries information The relation between two successively received signals: The maximum likelihood demodulation : 3

Outline Differential Space-Time Modulation (DSTM) New scheme for MIMO systems Simulation and comparison Conclusions 4

The constellation of the new scheme For MIMO systems with 2 transmit antennas, the transmitted information matrices are selected from the Weyl group Gw (192 unitary matrices, 2×2). The Weyl group is a set that contains 12 cosets. with where the matrices are: 5

The constellation of the new scheme The distance between two matrices Ma and Mb: The distance spectrum of the Weyl group: 6

The scheme with 2 transmit antennas Fundamental differential transmission relation: … There are 192 matrices in the Weyl group, the maximum spectral efficiency is 7

The scheme with 4 transmit antennas Kronecker product is used to expand the Weyl group For example, for R = 1 system where Actually, there are 4608 distinct matrices in the new group Gw4. The maximum spectral efficiency is 8

The scheme with 4 transmit antennas The performance can also be improved considering the distance spectrum For example, for R = 2 system, we select the first 16 matrices from every successive 192 matrices of the group Gw4, i.e., the set is This set has a better distance spectrum than the original one. Simulation results show the advantage of using this set. 9

Outline Differential Space-Time Modulation (DSTM) New scheme for MIMO systems Simulation and comparison Conclusions 10

Comparisons Performance comparison for 2 transmit antennas of different schemes (R=2) 11

Performance comparison for 4 transmit antennas of different schemes Comparisons Performance comparison for 4 transmit antennas of different schemes 12

Simulation results for different spectral efficiencies Performance for 4 transmit antennas with different spectral efficiencies 13

Outline Distributed MIMO broadcasting Space-Time codes for distributed MIMO broadcasting Simulation and comparison Conclusions 14

Conclusions The new 4×4 MIMO scheme higher spectral efficiency than Tarokh’s Differential STBC scheme the BER performance can be improved by selecting the set of transmission matrices having the best distance spectrum Can be expanded to MIMO systems with 8 transmit antennas 15

Thank you!