Knowledge Checks

Elements of 4G architecture.

Match the function of an element in the 4G LTE architecture with its name, using the pulldown menus.

Question List:

Located in a mobile device’s home network, this element provides authentication, access privileges in home and visited networks.

This router in a cellular carrier’s network, coordinates packet forwarding and routing to outside the carrier’s network.

This element coordinates mobile device services - authentication, mobility management - for a mobile resident in that network.

This element is on the network side of wireless link into the LTE network.

This element is the wireless link between mobile device and a base station

Answer List:

PDN-Gateway (P-GW)
Serving Gateway (S-GW)
Radio Access Network (RAN)
Home Subscriber Server (HSS)
Mobile device
Mobility Management Entity (MME)
Base Station (eNode-B)

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1/6

IMSI.

In 4G LTE cellular systems, what is an International Mobile Subscriber
Identity (IMSI)?

A 64-bit identifier that identifies the cellular network to which an mobile subscriber is attaching. Somewhat analogous to the Autonomous System (AS) number used in BGP to identify/name networks.

A 64-bit identifier stored on a cellular SIM (Subscriber Identity Module) card that identifies the subscriber in the worldwide cellular carrier network system.

Assigned by a mobile carrier network to a device, when the device attaches to the radio access network, serving a similar link-layer role as MAC addresses in a wired network.

A fancy name for a globally unique phone number, including country code.

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2/6

Comparing three wireless network types.

Consider three wireless networks that we learned about: WiFi (802.11), 4G LTE, and Bluetooth. Match each of these types of networks to a characteristic on the right.

Question List:

WiFi (802.11)

4G/LTE

Bluetooth

Answer List:

Can provide the farthest coverage (i.e., longest range wireless communication) from a base station.
Consumes the least amount of power.
Has the maximum link capacity (i.e., can deliver more bits/sec to the edge device).

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3/6

Power conserving “sleep modes”.

Which of the following statements is true about “sleep modes” that allow a wireless device to “sleep” and occasionally “wake up” as a technique for saving battery life?

LTE provides sleep modes but WiFi does not.

WiFi provides sleep modes but LTE does not.

Neither WiFi nor LTE provide sleep modes.

Both WiFi and LTE provide sleep modes.

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4/6

Connecting 4G cellular networks together.

Which of the following statements is true about how 4G cellular networks (operated by different carriers/companies) connect together?

4G networks connect to each other using the existing phone interconnection networks from earlier 3G and 2G networks.

In a 4G network, the radio access network connects to the legacy phone network for voice calls, but to the public Internet for data connections.

4G networks are generally all-IP, and so cellular networks interconnect (peer) directly to each other, or peer at the cellular equivalents of the Internet Exchange Points that we saw used for interconnecting wired networks in the public Internet.

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5/6

Reliable data transfer at the link layer.

Which of the following statements is true about the link-level service of reliable data transfer (using ACKs) in WiFi (802.11) networks and in 4G cellular networks?

Neither WiFi nor LTE provide link-level reliable data transfer.

LTE provides link-level reliable data transfer but WiFi does not.

WiFi provides link-level reliable data transfer but LTE does not.

Both WiFi and LTE provide link-level reliable data transfer.

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6/6

Knowledge checks

Elements of 4G architecture.

Question List:

Answer List:

IMSI.

Comparing three wireless network types.

Question List:

Answer List:

Power conserving “sleep modes”.

Connecting 4G cellular networks together.

Reliable data transfer at the link layer.