EC week Review

Rules of Engagement Teams selected by instructor Host will read the entire questions. Only after, a team may “buzz” by raise of hand A team must answer the question within 5 seconds after buzzing in (must have answer at hand) If the answer is incorrect, the team will lose its turn and another team may buzz in. No score will be deducted. No negative scores. Maximum score is 100. Once reached, that team will stand down for others to participate. Teams will earn all points scored at the end of game. When selecting a question, Teams must only select questions of different value, unless there are no others, but may be from different categories. All team members will participate and will answer questions Only one round - No Daily Doubles, Double Jeopardy or Final Jeopardy … and no partial credits!

Jeopardy! BGP / BGP Routing Comm Sys. EM Spectrum, Signals, Modulation A/D Conversion Digital Modulation Power Gain, SNR, Antennas Propagation / Electronic Warfare 10 pts 20 pts 40 pts 60 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 10 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 20 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 40 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts 60 pts

Briefly describe each of the following Autonomous Systems Categories: (a) Stub AS (b) Multihomed AS (c) Transit AS BGP/BGP Routing 10 pts -Has only one connection to another AS -Has more than one connection to other ASes, but doesn’t allow data to pass through it -Connects to more than one AS and allows traffic to pass through it

Name the four basic components of a communications system. Comm Sys., EM Spectrum, Signals, Modulation 10 pts Transmitter Receiver Channel Noise

What is the most important advantage of digital communications? A/D Conversion 10 pts Relative Noise Immunity – a digital system only has to decide between a finite set, e.g. binary 0 or binary 1 for a binary digital receiver, which is easier even amid of a significant noise.

What digital modulation scheme does each constellation represent? Digital Modulation 10 pts BPSK QPSK 8-PSK 16-PSK 8-QAM

Antenna Type Azimuth beam pattern Vertical beam pattern Physical size Dipole (vertically oriented) Monopole (vertically oriented) Yagi (of the driven element) Fill in the missing information for each antenna type. Gain, SNR, Antennas 10 pts omnidirectional Depends on gain (it varies) null Depends on gain (it varies)

For VLF-HF communications, list and describe the basic modes of propagation Propagation/EW 10 pts Ground wave – EM waves that travel close to the surface of the earth Sky wave – EM waves that travel up into the atmosphere and then bend back to earth Space wave – EM waves that travel in a straight line (direct line-of-sight or LOS)

Describe the steps followed in BGP routing when selecting a route. BGP/BGP Routing 20 pts 1)a BGP router first attempts to find all paths from the router to a given destination 2)it then judges these paths against the policies of the AS administrator 3)it then selects a “good enough” path to the destination that satisfies the policy constraints

What is the wavelength of a radio station whose broadcast frequency is MHz? Comm Sys., EM Spectrum, Signals, Modulation 20 pts

What is quantization error and how can it be mitigated? A/D Conversion 20 pts Quantization error is the difference between the original analog signal and the reconstructed (stairstep) signal after A/D and D/A. Quantization error can be reduced by increasing the number of bits N for each sample. This will make the quantization intervals smaller, reducing the difference between the analog sample values and the quantization levels.

Digital Modulation 20 pts

Gain, SNR, Antennas 20 pts Given the following radiation pattern, where each ring represents a 2 dB change in power  What is the beamwidth?  What is the sidelobe level?  What is the front-to-back ratio? ~ 30º

Propagation/EW 20 pts Consider the diagram and formula below. What is the longest line-of-sight communication range between a transmitter on a DDG with an antenna 130 feet high and a receiver on a small craft with an antenna 12 feet high.

BGP/BGP Routing 40 pts What AS path would an IP packet from take to reach ? What AS path would an IP packet from take reach ? What AS path would an IP packet from take to reach ? 40 – 2003 – – 40 – 2003 – 2005 Consider the network diagram and BGp route announcement from Router 3 below, assuming no local preferences are set.

What is the time-domain expression of the following modulated signal? Comm Sys., EM Spectrum, Signals, Modulation 40 pts

Consider the frequencies for a bass guitar below. What minimum sampling frequency must be exceeded in order to accurately reconstruct the signal and avoid aliasing? A/D Conversion 40 pts Source:

Consider the code provided for an 8-PSK system. What would be the bit stream for the phase shifts received as (0°) (225°) (45°) (90°)? If the phase shifts are received at 20 µs intervals, what is the baud rate? What is the bit rate? Digital Modulation 40 pts Ans:

Gain, SNR, Antennas 40 pts The signal power at the input to the receiver is 6.8 nW and the noise power at the input to the receiver is 2.4 nW. Find SNR. A transmitter feeds a dipole antenna (gain G = 1.64) with 150 Watts of power. Calculate EIRP.

Propagation/EW 40 pts

Name and describe (include negative and positive consequences) one technical solution that an AS network operator can use to combat prefix hijacking an MITM attack on BGP networks? BGP/BGP Routing 60 pts Filtering – Best current practices for AS network operators dictate the use of filters at AS borders to reject suspicious route announcements or alter malicious route attributes. Filters are manually established based on the routing policies of an organization. Filtering has both a business cost and computational cost associated with it. Internet Routing Registries – These are repositories of the IP prefixes, ASNs, routing policy, network topology, and human points of contact for those ASes which choose to register their information. While this method may be effective, the downside is that these registries are only effective if the registry data is secure, complete, and accurate, which is currently not guaranteed. Resource Public Key Infrastructure (RPKI) – Similar to the IRRs, RPKI is a repository of Internet routing information. The key difference is that it uses the X.509 certificate system to provide cryptographic assurance of (1) the association between an ASN and the IP prefixes it has been allocated, and (2) the association between an ASN and the IP prefixes it is authorized to originate.  There is nothing in RPKI which validates the route attributes, including the AS path, associated with a BGP route announcement from an AS.  Nor does it provide certainty that the AS which has registered their information used the correct ASN or set of prefixes.  Nor does it provide network topology information or human points of contact as with IRRs.  Lastly, it does not mandate that network operators use this information when constructing their filters.  How RPKI is applied is entirely dependent on what AS network operators choose to do with the information available.

Comm Sys., EM Spectrum, Signals, Modulation 60 pts

Consider the following analog waveform. It is to be sampled at 2 MHz and quantized with a 2-bit quantizer (input voltage range is -2.0 V to +2.0 V). Using digital bits sequentially from low to high, what is the series of transmitted bits representing the waveform? A/D Conversion 60 pts Ans: (Underlined bits are borderline)

Digital Modulation 60 pts As more symbols are added, their phases get closer making the system more susceptible to noise as correctly differentiating between symbols would be more difficult.

Gain, SNR, Antennas 60 pts For the diagram below, P in = 2 mW, A P1 = 10, A P2,dB = -4 dB, and A P3,dB = 3 dB. Calculate P out,dBW

Propagation/EW 60 pts

Score Card TeamTallyScore