Wireless Signals and Modulation - Carrying Data Over an RF Signal

3 important questions on Wireless Signals and Modulation - Carrying Data Over an RF Signal

Due to the physical properties of an RF signal, there is only 3 options to send data with the signal. Which 3?

1. Alter frequency, but only slightly above or under carrier frequency.
2. Alter the Phase
3. Alter the Amplitude

Modern Wireless LANs use 'Spread Spectrum' to send data across a band of frequencies. What are the 2 most common spread-spectrum categories?

1. DSSS: Direct Sequence Spread Spectrum. Used in 2,4 Ghz
2. OFDM: Orhogonal Frequency Division Multiplexing. Used in both 2,4 Ghz and 5 Ghz.

What is SISO and MIMO?

Stands for Single Input Singe output and Multiple Input Multiple Output respectively.
Traditional devices were SISO written as 1x1 or 1 Transmit 1 Receive radio chain.
modern MIMO devices can ben 2x2, 2x3 or 4x4 for example. Where 2x3 would be 2 Transmit and 3 Receive radio chains.

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