CWNA

Answer - B - The number of phase shifts provided by DQPSK is 4.

Key Takeaway: Differential Binary Phase Shift Keying, or DBPSK, utilizes two phase shifts: one that represents a 0 chip and another that represents a 1 chip. Differential Quadrature Phase Shift Keying or DQPSK provides faster throughput by utilizing four phase shifts. This allows each of the four phase shifts to modulate two chips (00, 01, 10, 11) instead of just one chip. This doubles the speed.