IEEE 802.15.4 defines two physical media.

IEEE 802.15.4 defines three physical media.

IEEE 802.15.4 defines four physical media.

Maximum PSDU in IEEE 802.15.4 physical layer packet is 127 bytes of data.

Maximum PSDU in IEEE 802.15.4 physical layer packet is 128 bytes of data.

Maximum PSDU in IEEE 802.15.4 physical layer packet is 256 bytes of data.

The data modulation of the 2.4 GHz physical layer is quaternary modulation.

The data modulation of the 2.4 GHz physical layer is M-ary modulation.

The data modulation of the 2.4 GHz physical layer is 16-ary orthogonal modulation.

Contention-based channel access in IEEE 802.15.4 does not address the hidden terminal problem.

Contention-based channel access in IEEE 802.15.4 does address the exposed terminal problem.

Contention-based channel access in IEEE 802.15.4 does address the hidden terminal problem.

The MAC control frame is used by the MAC entities in different devices for negotiation and communication.

The MAC command frame is used by the MAC entities in different devices for negotiation and communication.

The MAC data frame is used by the MAC entities in different devices for association and disassociation.

Controlled flooding is worse than flooding.

Gossiping is worse than flooding.

Controlled flooding is better than flooding.

Routing tables are determined by the routing protocol.

Routing tables are determined by the MAC protocol.

Routing tables are determined by the routing algorithm with the help of the routing protocol.

In MMBCR, the sum of all reciprocal levels of all nodes along a path is used as the cost of that path.

In MMBCR, simply the largest reciprocal level of all nodes along a path is used as the cost of that path.

In MMBCR, simply the smallest reciprocal level of all nodes along a path is used as the cost of that path.

The braided path may have some nodes and links common with primary path.

The braided path may have all nodes and links disjoint with primary path.

The braided path has some nodes and links common with primary path.

A WSN’s task is not to transport data, but to observe and possibly control.

A WSN’s task is to transport data, but not to observe.

A WSN’s task is to transport data, but not to observe and possibly control.

The range of path loss for engineering building in 800-1000 MHz is [-38.2, -35.0].

The range of path loss for engineering building in 800-1000 MHz is [-36.4, -35.0].

The range of path loss for engineering building in 800-1000 MHz is [-50.5, -39.0].

IEEE 802.11 divide their spectrum in the 2.4 GHz band into 58 sub-bands.

IEEE 802.11 divide their spectrum in the 2.4 GHz band into 48 sub-bands.

IEEE 802.11 divide their spectrum in the 2.4 GHz band into 78 sub-bands.

Bandwidth efficiency of 8-ary PSK is 1.5.

Bandwidth efficiency of 8-ary FSK is 1.5.

Bandwidth efficiency of 16-ary PSK is 1.5.

The path loss exponent of air typically varies between 2.5 and 5.

The path loss exponent of air typically varies between 3 and 5.

The path loss exponent of air typically varies between 2 and 5.

Frequency non-selective channel is also called fast fading channel.

Frequency selective channel is also called flat fading channel.

Frequency non-selective channel is also called flat fading channel.

By choosing a small duty cycle, the wireless transceiver is in sleep mode most of the time.

By choosing a small duty cycle, the wireless transceiver is in sleep mode rarely.

By choosing a small duty cycle, the wireless transceiver is in active mode most of the time.

STEM protocol provides a solution for the idle listening problem.

RTS-CTS protocol provides a solution for the idle listening problem.

CSMA protocol provides a solution for the idle listening problem.

To reduce the probability of collisions, the routing protocol uses random delays and is called CSMA/CD.

To reduce the probability of collisions, the routing protocol uses random delays and is called CSMA/CA.

To reduce the probability of collisions, the routing protocol uses fixed delays and is called CSMA/CA.

IEEE 802.11 has a range of ~ 10 meter.

IEEE 802.15.4 has a range of ~ 100 meter.

IEEE 802.11 has a data throughput 2~ 54 Mbps.

IEEE 802.11b uses DSS modulation.

IEEE 802.11b uses FHSS modulation.

IEEE 802.11b uses OFDM modulation.

Step index

Graded index

Step and graded index

Coaxial cable

Coaxial cables

Standard single mode fibers

Standard multimode fibers

Non zero dispersion shifted fibers

A loss mechanism related to the material composition and fabrication of fiber

A transmission loss for optical fibers

Results in attenuation of transmitted light

Causes of transfer of optical power

onization

Radiation

Suitable choice of core and cladding components

Melting

8.60μ_m

9.30μ_m

9.1μ_m

10.2μ_m