High Speed Data Customer Service
What system is a byproduct of the "funneling effect"?
A many-to-one system.
What device causes WiFi interference?
Analog wireless security cameras
What are the options if signal strength is too low for what the customer is trying to use the network for?
If the signal strength appears to be too low, either address the dead spot by moving the router or adding an access point, or set expectations with the customer by explaining the signal strength issue
How are optical Splitters used in the forward path?
In the forward path, optical splitters are used as passive branching devices that divide an optical signal across multiple output fibers
Frequency-Hopping
rapidly hops from frequency to frequency, spreading activity all over the band
Utilization
the measurement raw RF activity on a channel and how often the channel is in use that can be measured by a spectrum analyzer
Which 802.11 standard takes more time to send and receive data, thus causing congestion on the 2.4 GHz band?
802.11b
What is the last step in a cable modem's registration?
When the cable modem termination system (CMTS) receives a registration acknowledge (REG-ACK) message confirming the modem's registration.
The attribute of being "active" as a critical thinker means
You observe and take notes relevant to the issue.
Non-WiFi Interference
comes from devices, such as cordless phones, wireless sound bars, and even leaky microwave ovens
What must you do when adding an additional access point?
configure it with the same service identifier (SSID), security settings, and a proper channel
What can cause wifi interference?
dense objects like refrigerators and fish tanks
What is the path for signals being distributed from the headend called?
forward or downstream path
Narrowband
intensely uses a narrow slice of frequency space without moving; tend to cause heavy utilization on whatever frequency they choose, which will most certainly jam a wireless network
You are at a customer's home, and you are asking the customer whether the problem is intermittent or constant. Which steps are you using from the six-step troubleshooting process?
isolating the elements
Primary types of interference in Wi-Fi
1. adjacent-channel interference 2. non-wifi interference
When calculating return path attenuation in the drop system, what is the attenuation loss through the hot-leg of an unbalanced three-way splitter at sub-split frequencies?
3.5 dB.
When using a digital signal analyzer to troubleshoot data throughput in the DOCSISData Over Cable Service Interface Specification network, what is the minimum MERModulation error ratio into the cable modem for a 256-QAMQuadrature amplitude modulation carrier?
32 dB or greater.
What would be the downstream throughput if two QAM Quadrature amplitude modulation channels with a throughput of 38 Mbps Megabits per second were bonded?
76 Mbps.
IEEE Standards and the Supported Frequencies
802.11a and 802.11ac - 5 GHz 802.11b and 802.11g - 2.4 GHz 802.11n - 2.4/5 GHz
Which of the following channels represents a well performing network?
A channel that is utilized less than 50% of the time.
What device can be installed with a DOCSIS modem to enable Internet access to multiple devices in the customer premises?
A router with a built-in multi-jack Ethernet switch.
It is essential to pay attention to warning signs of stress overload. Poor attitude is one of the behaviors that may indicate that you are overstressed. What are the symptoms of poor attitude behavior?
A significant change in attitude with a noticeable movement toward negative, hostile, cynical, or paranoid thoughts.
What is the maximum signaling rate for a 2SS device, such as a budget laptop or premium tablet?
A two-spatial stream (2SS) device, such as a budget laptop or premium tablet, achieves a signaling rate of 120 Mbps
Installing a DOCSIS modem and router in a smart panel or utility room is simplified by having what items in the room?
Access to the coaxial cable so that it can be routed to the DOCSIS modem, an electrical outlet to power the DOCSIS modem and router, and an unshielded twisted-pair (UTP) network cable that is labeled and has connectors installed using standard wiring configurations.
What is the difference between the fiber-to-the-node (FTTN) and fiber-to-the-curb (FTTC) topologies?
An FTTC is allowed a smaller number of RF amplifiers between the optical fiber and the customer premises
What instructions might a cable modem termination system (CMTS) send in a ranging response (RNG-RSP) message to modify the cable modem's transmission parameters?
An adjustment to the modem's timing interval, transmit frequency, or power level.
What does a DOCSIS 3.1 seek first when synchronizing with the cable modem termination system (CMTS) in order to receive operational information?
An orthogonal frequency division multiplexing (OFDM) channel that contains a set of contiguous subcarriers called the PHY link channel (PLC).
What messages must a cable modem receive from the downstream signal in order to begin a transmitting relationship with the cable modem termination system (CMTS)?
An upstream channel descriptor (UCD) message, a symbol timing message (SYNC), and a bandwidth allocation message (MAP).
What non-Wi-Fi device utilizes 20 MHz of spectrum, which is nearly the same as a Wi-Fi network and, due to its heavy utilization, can cause a Wi-Fi network to stop working entirely?
Analog wireless security camera.
How does the signal attenuation through coaxial cable in the sub-band frequency spectrum compare to the attenuation at forward path frequencies?
At sub-band frequencies, the signal attenuation is significantly less than in the forward path.
Some cable operators charge an additional fee when the amount of downloaded data during a billing cycle exceeds a prescribed limit. How might a customer unknowingly approach these limits?
By streaming and downloading high-content data, such as movies and TV shows in high-definition (HD) throughout the billing period.
What is one reason why broadband cable operators install fiber optic cable in stages instead of changing the infrastructure all at once?
Changing the infrastructure all at once would cause too many service disruptions
In a DOCSISData Over Cable Service Interface Specification network, why is the data throughput over the return or upstream path typically less than the throughput of data over the forward or downstream path?
Compared to the downstream path, the narrower bandwidths and lower orders of modulation used to transport data over the return path cause the downstream and upstream data throughput to be unequal or asymmetrical.
What are the options for Wi-Fi if the 2.4 GHz band is over-crowded?
Connect devices with Ethernet and/or Move devices to the 5 GHz band
Which version of the Data Over Cable Service Interface Specification (DOCSIS) included the option to increase the top frequency of the upstream to 85 megahertz (MHz)?
DOCSIS 3.0
If the customer demonstrates that they are experienced with accessing the Internet savvy, what should be the next step in the customer education portion of the high-speed data (HSD) service installation?
Direct the customer to the cable operator's web page to show them what information is available and to help them set up their email account.
Why can FTTX applications be more susceptible to the adverse effects of macro- and microbends than typical transmission applications?
FTTx standards use some wavelengths that are longer than typical transmission wavelengths, and are therefore more susceptible to the adverse effects of macro and microbends
Which technique can be useful in helping others understand your emotional state and in providing them with direction around how to help you restore balance?
Feel, Felt, Found technique.
House amplifiers with a passive return path are used for what type of situation?
For situations when long service drops are used and the forward path needs to be amplified but return path amplification is unnecessary.
How does a DOCSIS modem receive its Internet protocol (IP) address?
From a dynamic host configuration protocol (DHCP) server that provides the CMTS with the modem's IP address, which is forwarded to the modem during initialization.
Which is better, having networks that share a channel or having partially overlapping networks?
Having networks that share a channel is better than having partially overlapping networks
How does IP multicast differ from IP broadcast?
IP multicast traffic is only sent to specific modem addresses on the network; IP broadcast traffic is sent to all modems on the network.
What Internet protocol (IP) connectivity modes are supported in DOCSIS 3.0 and 3.1?
IPv4 only, IPv6 only, alternate provisioning mode (APM), and dual-stack provisioning mode (DPM).
What could you do if there are no good channel options in the 2.4 GHz band for your customer's 802.11n device?
If available, connect devices with Ethernet.
What is the relationship between spatial streams and speed?
Increasing the number of spatial streams increases speed and reliability
What type of security does the baseline privacy interface (BPI) protocol provide?
It prevents a cloned modem from full, illegal, access to the network.
What layers of the OSI reference model are specific to cable networks and are present only between DOCSIS modems and the CMTS?
Layers 1 through 4 (Physical layer, Data Link Layer, Network Layer, and Transport Layer) are applied between the DOCSIS modem and CMTS.
Types of devices that can cause interference to Wi-Fi
Microwave ovens Wireless microphones Wireless video systems Security systems Home automation equipment Wireless sound bars Wireless subwoofers
By taking control of the expectations you have, you are?
More likely to improve your motivation and be a better problem solver.
Why should you take the time to take notes and accurately record data at each job location?
Notes and recorded data are tools that can help you accurately remember events at a site that can help you determine a plan of action or evaluate the decisions you made
What are two features that were added in DOCSISData Over Cable Service Interface Specification 3.1 to extend the viability of HFCHybrid fiber/coax networks into the next decade?
OFDM Orthogonal frequency division multiplexing and LDPC Low-density parity-check
Which of these components is used in a passive optical network (PON)?
Optical Splitters
What did the 1.1 version of the DOCSISData Over Cable Service Interface Specification introduce, incorporating solutions for transporting real-time data applications (such as voice traffic) over the cable operator's managed IP network, and doing so with quality comparable to that of the telephone company?
PacketCable.
What could be attributed to a device that has good signal strength from the router but disconnects once every few minutes?
Poor performance could be attributed to non-Wi-Fi interference.
Which of the following best describes stereotyped thinking?
Presuming that all members of a group have certain characteristics.
What can determine the speeds a device will achieve over a Wi-Fi network?
Processor RAM Storage read and write speed Amount of applications running Type of throughput test
What other device factors determine what speeds a device will achieve over a Wi-Fi network?
Processor and storage read/write space.
Which of the following works well in a noisy environment and is used when the category of data requires reliable delivery over speed and where the frequency spectrum is noisiest?
QPSK because it is a low-data rate modulation scheme; many networks use QAM for upstream DOCSIS transmissions to achieve higher data rates in the return path
What is it about radio frequency over glass (RFoG) that made broadband cable operators envision using it to make a seamless transition from the legacy hybrid fiber/coax (HFC) architecture over to a gigabit-capable passive optical network (GPON) or Ethernet passive optical network (EPON)?
RFoG can operate in parallel with GPON or EPON, which eliminates the need for any downtime during the transition
What enables STBSet-top boxess and DOCSISData Over Cable Service Interface Specification modems to operate as completely separate systems that operate independent of each other?
STB and DOCSIS modems are assigned different upstream channels with dedicated receivers in the headend.
What should a technician do if Wi-Fi signal strength appears to be too low for what the customer is trying to use the network for?
Set expectations with the customer by explaining the signal strength issue.
How are STB's and DOCSIS modem's data assigned to upstream channels?
Set-top boxes (STB) and DOCSIS modems are assigned different upstream channels with dedicated receivers in the headend, enabling them to operate as completely separate and independent systems
What determines the maximum speed capabilities of a device?
Spatial streams.
Which step in the troubleshooting process requires a discussion with the customer to gather more detail about the problem?
Step 1: Identify the problem.
When helping a new customer set up email for the first time, what suggestion should you make regarding the customer's email login ID and password?
Suggest that they write their email login ID and password down and keep it in a safe place in case they forget it.
What could be done if co-channel interference is found to be the reason for slower data rates?
Switch the network to another channel that is less congested.
A narrow slice of spectrum appears on the 2.4 GHz band that may or may not cause congestion when this button is pressed on a 2.4 GHz cordless phone?
Talk.
To break the habit of a negative self-talk cycle?
Tell yourself "not now" and move on to a positive thought whenever negative thoughts occur.
Which DOCSISData over Cable Service Interface Specification layer is used by the CMTSCable modem termination system to differentiate between cable modems?
The DOCSIS MAC Media Access Control Layer.
Where should the customer be encouraged to go for information and questions before calling customer service?
The customer information package provided to the customer during the installation. The information and answers provided are always current.
What can be checked on the digital set-top box (STB) to verify the reliability of the customer's drop system?
The diagnostic page for downstream performance data such as bit error rate (BER) and modulation error ratio (MER).
What happens if a DOCSIS modem is unable to acquire the current time and date from one or more time-of-day (ToD) servers during registration with the cable modem termination system (CMTS)?
The modem proceeds to an operational state and issues at least one ToD request per 5-minute period for each server specified until local time is established.
What information does a DOCSIS 3.1 modem provide in its Bonded Initial Ranging Request (B-INIT-RNG-REQ) message to the cable modem termination system (CMTS)?
The modem's downstream service group (DS-SG), if determined.
What enables the return path to be shared by regulating when the devices transmit in order to prevent collisions?
The multiple access portion of TDMA
What enables the STBSet-top boxes upstream carrier to be located below 20 MHz and still be reliably received?
The narrow bandwidth and QPSK Quadrature phase shift keying modulation.
What was introduced in DOCSIS 3.0 to allow enough bandwidth for upstream carriers from previous DOCSIS versions?
The option to increase the top frequency of the upstream to 85 MHz.
What is the smallest allowable bend radius for G.652 standard single-mode fiber?
The smallest allowable bend radius for G.652 standard single-mode fiber is 30mm
When analyzing a problem, what can the technician learn by asking the customer to show or demonstrate the problem?
The symptoms of the problem can be viewed, and any unusual screens or customer entries can be identified.
Why is 38 MHz typically the highest frequency in the sub-band frequency that is used for upstream modem transmissions?
The upper edge of the sub-band frequency spectrum is prone to group delay caused by the diplex filters.
If the customer is an Internet novice, what would be the benefit of saving your company's website as their home page?
They might appreciate having easy access to a website that contains links to their email and other useful or interesting links.
Which of the following statements describes creative problem-solving?
Thinking outside of the box and looking at problems from a fresh perspective.
Why does the output level from CPECustomer premises equipment vary?
To compensate for variable amounts of attenuation in the return path of each device.
Why would a cable operator consider activating device class identification (DCI) as part of a DOCSIS modem's initialization?
To enable the cable operator to define special modem classes or service levels that can be prioritized for ranging after a massive outage.
What purpose do diplex filters fulfill when installed at the input and output of a two-way amplifier module?
To route the forward and return signals over different circuit paths to the appropriate section so that they can be amplified separately.
Why is it a good practice to review the service work order with the customer before beginning a high-speed data (HSD) service installation?
To verify account information and to confirm the HSD service order.
What should you do if a client device keeps defaulting to the 2.4 GHz network over the 5 GHz network?
Use different SSID for each network.
What are the three primary elements of a PON?
Using terminology from the telephone industry, the main elements of a PON are the optical line terminal (OLT), the optical distribution network (ODN), and the optical network unit (ONU)
You are at a customer's home, and you believe you have solved the problem. When you check to ensure the resolution did not introduce any new problems, which step are you using from the six-step troubleshooting process?
Verify the solution.
What if there are several networks above -85 dBm that are partially overlapping?
it causes retries, which in turn causes congestion. At this point, it is a good idea to try to find a better channel that avoids adjacent-channel interference
Is it better to have networks that share a channel or to have partially overlapping networks?
it is better to have networks that share a channel, so it's okay to move to a channel with more networks to avoid overlap
What should you do if the customer's 5 GHz-capable devices still refuses to connect to the 5 GHz SSID?
it is possible to turn down the transmit power of the 2.4 GHz radio and, possibly, turn up the transmit power in the 5 GHz radio or you can use different SSIDs for the 2.4 and 5 GHz bands
What percentage of utilization can you expect the network to perform well?
less than about 50 percent of the time; when utilization reaches more then the channel is too congested, at which point it is best to switch to a different channel
What are the two varieties that 2.4 and 5 GHz cordless phones tend to come in?
narrowband and frequency-hopping
Adjacent-Channel Interference
occurs when networks are on partially-overlapping channels, which causes devices to talk over each other, corrupting transmissions (which in turn leads to retransmissions)
