How to compare two 802.15.4 O-QPSK modulated digitals signals?

1. Which modulation technique is used in IEEE 802.15 4?
2. Which modulation scheme is followed by IEEE 802.15 4 standard BPSK QPSK DSSS all of these?
3. What are the two types of network access used in IEEE 802.15 4 networks?
4. What are the major limitations of IEEE 802.15 4 standard?

Which modulation technique is used in IEEE 802.15 4?

The 2.4 GHz band uses the direct sequence spread spectrum (DSSS) modulation technique.

Which modulation scheme is followed by IEEE 802.15 4 standard BPSK QPSK DSSS all of these?

According to the IEEE 802.15. 4 standard, the offset quadrature phase shift keying (O-QPSK) direct sequence spread spectrum (DSSS) scheme is required in 780/868/ 915/2380/2450 MHz frequency band [4], [5].

What are the two types of network access used in IEEE 802.15 4 networks?

IEEE 802.15. 4 identifies two different types of network nodes: reduced function devices (RFD) and full-function devices (FFD).

What are the major limitations of IEEE 802.15 4 standard?

The main disadvantage of the IEEE 802.15. 4 is the number of GTS slots is limited to seven. In WBAN, nodes generally require more GTS slots in the CFP period. This can be achieved by the varying the CFP duration according the applications.