Configure Mobile Device Network Support Flashcards
What options are there for accessing a cellular data network from a non-smartphone device?
- Cellular enabled: laptops and tablets can be enabled to access a cellular network through use of a SIM or other cellular access method. Typically requires a monthly subscription to a cellular provider and a cellular enabled device
- Hotspot: ad-hoc WiFi networks can be created either through the smartphone or a dedicated hotspot device
- Tethering: Uses a wired connection between PC and phone, allowing PC to access cellular data network
How are PRIs and PRLs updated?
- Typically automatically updated over the air with the cell towers the device communicates with
- Updates can be forced with a code entered on the device’s keypad (##873283## for TMobile)
What information is on a SIM card?
- Manufacturer ID: The manufacturer or provider of the SIM (for example T-Mobile or Verizon)
- Account ID: Information related to the individual subscriber who is paying for access to the cellular network
- Hash: A hash of the previous information to prevent tampering
What is a SIM card?
- Stands for Subscriber Identity Module
- A chip that contains identity information used to access a cellular network
- Identifies the provider and subscriber of the SIM
What multiple access solution is used by 5G cellular technology?
LTE (FDMA)
What challenge exists with having multiple users accessing the same cellular tower?
- Multiple users accessing the same tower can cause interference with each other when trying to transmit data simultaneously.
Describe CDMA
- Code Division Multiple Access (CDMA)
- Each user has a unique spreading code used to encode/decode data
- Multiple users’ data is combined in a shared waveform
- Individual user data can be extracted using the user’s unique code
What multiple access solution is used by 2G cellular technology?
Time Division Multiple Access (TDMA) or Code Division Multiple Access (CDMA) depending on the carrier
What is the PRI?
- Product Release Instructions
- Contains country and network codes as well as device identification data necessary to connect to a cellular network.
What are the differences between 2.4 and 5 GHz signals?
- 2.4 GHz is a longer, lower frequency wavelength. Can be better at propagating signal through walls between an AP and end user machine
- 5 GHz has more channels (less likelihood for interference between APs) and better data utilization. 5 GHz better at dealing with interference from microwaves and baby monitors
What controls the cellular towers a device uses?
- The Preferred Roaming List (PRL)
- Indicates the bands, sub-bands and provider IDs a device will search for
- Uses this information to connect to the correct cellular tower, preferring towers from the same provider or those in partnership with the provider.
What multiple access solution is used by 4G cellular technology?
WiMax and LTE (FDMA)
What is baseband?
The technology used to facilitate communication between a cellular device and cell towers in the area.
Why does poor wireless signal degrade battery life on a device?
The device can boost its own wireless signal to access the antenna or AP it is communicating with. Boosting its own signal requires more power, draining the battery faster and increasing heat output from the device.
What technologies exist to mitigate interference between multiple users accessing the same cellular tower?
- Time Division Multiple Access (TDMA)
- Code Division Multiple Access (CDMA)
- Frequency Division Multiple Access (FDMA)
What use does a cellular data network have outside of providing internet access to a smartphone?
- Useful for traveling or when primary internet connection goes down
- Can provide internet access to PC or other devices through hotspots or tethering
What is roaming in the context of cellular networks?
Refers to the use of cell towers from a different provider.
How is baseband updated?
Baseband updates are typically packaged with updates to the smartphone OS.
How are wireless frequencies measured?
- In Hertz (Hz)
- Refers to the wavelength frequency of the wireless signal
- Modern signals use GigaHertz (GHz)
What is an AP?
- Access Point
- Used in WiFi
- A device that produces a wireless signal that allows access to a network
What is the IMSI and what information does it contain?
- International Mobile Subscriber Identity
- Stored on SIM card
- Identifies subscriber account info:
- Mobile Country Code (MCC): country of origin
- Mobile Network Code (MNC): Service Provider
- Mobile Station ID (MSID): Used by provider to identify user
What is the IMEI and what information does it contain?
- International Mobile Equipment Identity
- Burned in number that uniquely identifies a device accessing a cellular network
What determines signal strength in a WiFi network?
- Typically determined by distance from the AP where a radius around the AP defines the area it covers
- Some difference in signal strength between WiFi standards and frequencies used
Describe FDMA
- Frequency Division Multiple Access (FDMA)
- Each device is designated a channel to communicate over
- This channel represents a frequency range that does not interfere with other channels
- allows for multiple users to transmit simultaneously on their unique channel without interfering with others
