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WorksheetsWimax Redline Preassessment
Total questions: 15
Worksheet time: 15mins
Name
Class
Date
1.
Which of the following most accurately describes a switch?
a)
Works at the OSI layer-2, understands the difference between broadcast and unicast packets, learns the physical address of the device sending packets to it and supports the 802.1Q/802.1p standard
b)
Works at the OSI layer-3, does not understand the difference between broadcast and unicast packets, learns the physical address of the device sending packets to it, supports the 802.1Q/802.1p standard
c)
Works at the OSI layer-2, understands the difference between the 802.1p and Differential Services Code Point (DSCP) markers.
d)
None of the above
2.
Which of the following best describes the physical address of a device such as a switch?
a)
It is an 8 bytes long sequence used to identify the device to a RADIUS and LDAP database
b)
It is a 6 Octets long string that uniquely identifies the device. The first 3 Octets identify the device’s manufacturer and the last 3 the device’s network interface card (NIC).
c)
It is a 32 bits long string that uniquely identifies the device
d)
None of the above
3.
Which of the following best describes a time division duplexing (TDD) system?
a)
A duplexing method that uses only one frequency to carry both downlink (DL) and uplink (UL) traffic on a link. A TDD system is essentially a half-duplex system
b)
A duplexing method that uses a pair of frequencies to carry both DL and UL traffic on a link
c)
A duplexing method using one frequency to carry both DL and UL traffic on a link concurrently
d)
None of the above
4.
Which of the following is more accurately talking about the frequency and wavelength of a signal?
a)
Signal wavelength is inversely proportional to its frequency and that is why low frequency signal antennas are very small compared to high frequency antennas for the same antenna gain
b)
Signal wavelength is directly proportional to its frequency and that is why low frequency signal antennas are the same size as the high frequency signal antennas for the same antenna gain
c)
Signal wavelength is inversely proportional to its frequency and that is why low frequency signal antennas are very large compared to high frequency signal antennas for the same antenna gain
d)
None of the above
5.
What is the antenna gain and how is it generally measured?
a)
It is the antenna ability to concentrate its input power to a specified beamwidth and is generally measured in dBi.
b)
It is the antenna ability to spread its input power 360 degrees around it and is measured in dBc.
c)
It is the antenna ability to amplify the input signal to a pre-specified level. The gain is measured in dB
d)
None of the above
6.
A two-RF-port transmitter outputs 39 dBm from each port. What is the total output of the transmitter?
a)
78 dBm
b)
36 dBm
c)
42 dBm
d)
None of the above
7.
What is the main difference between a tagged and an untagged Ethernet packet?
a)
A tagged Ethernet packet carries a VLAN ID while an untagged packet has no VLAN ID. Therefore, a tagged Ethernet packet is 4 bytes larger than an untagged packet
b)
A tagged packet carries a VLAN ID and an 802.1p marker while an untagged packet has only an 802.1p marker but VLAN ID. Therefore, a tagged Ethernet packet is 6 bytes larger than an untagged packet
c)
A tagged packet carries a standard VLAN ID while an untagged packet has an operator specified VLAN. Both tagged and untagged Ethernet packets have same minimum size of 62 bytes.
d)
None of the above
8.
What is the main difference between BPSK and QPSK?
a)
They are FSK modulation with BPSK carrying only two bits per symbol and QPSK four bits per symbol
b)
They are both PSK modulation with BPSK carrying only one byte of data per symbol while QPSK carries two bytes of data per symbol
c)
They are PSK modulation with BPSK carrying one bit per symbol and QPSK two bits per symbol.
d)
None of the above
9.
What is ARQ in the context of a PTP wireless link?
a)
ARQ is an error detection scheme in which the receiver performs a CRC check on the received packet. It discards erroneous received packets and ask for a retransmission from the transmitter.
b)
ARQ is an error detection and connection scheme in which the receiver performs a bit by bit integrity check on the received packets and corrects detected errors
c)
ARQ is an error detection scheme at the application layer in which the receiver performs a CRC check on the received packet. It simply flags the errors, so the TCP layer can connect the errors
d)
None of the above
10.
What is receiver sensitivity and what system requirement determines this parameter
a)
It is the maximum signal level a receiver needs to decode the received modulation symbol. The PER performance requirement of the receiver determines this parameter.
b)
It is the minimum number of bits a receiver needs to decode the received modulation. The range of temperature in which the device must work determines this parameter.
c)
It is the minimum signal level a receiver needs to decode the received modulation. The required BER performance of the receiver determines this parameter
d)
None of the above
11.
Which of the following requires more SNR compared to 64QAM to be correctly decoded at the receiver?
a)
16QAM and 32QAM
b)
128 QAM and 256QAM
c)
BPSK and QPSK
d)
None of the above
12.
How is the data transmission integrity checked in a wireless transmission
a)
Using a CRC, typically 4 bytes, sent with each packet by the transmitter and checked at the receiver
b)
Using error detecting bits inserted after every 64 bytes in wireless packet and check at the receiver
c)
Using a 32 bytes CRC sent with each packet by the transmitter and checked at the receiver
d)
None of the above
13.
What is VoIP and how is a VoIP packet generated
a)
It is an IP data packet having voice samples in native format and carried over the IP network. A VoIP packet is generated by a PBX.
b)
It is an IP data packet having digitized voice as payload and carried over the IP network. A VoIP packet is generated by a TDM to IP convertor
c)
It is a data packet carrying digitized voice in a GRE tunnel over the IP network. A VoIP packet is generated by a TDM to GRE convertor
d)
None of the above
14.
What is the main difference between BER and PER in a wireless system
a)
BER is a measure of the bit error rate at the physical layer while PER indicates the packet error rate at the MAC layer of a wireless receiver
b)
BER is a measure of the byte error rate at the physical layer while PER indicates the packet error rate at the TCP layer of a unit directly connected to a wireless receiver.
c)
BER and PER are both a measure of the total overhead used by a wireless transmitter
d)
None of the above
15.
What will a switch do if it receives a packet without a destination address specified in it
a)
It simply discards the packet.
b)
It broadcasts the packets to all its ports
c)
It sends to the port which has not received or sent any packets for 10 minutes.
d)
None of the above
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