CAPE MOB Unit 1 cheat sheet

Mobile computing is defined as a computing environment where users can access services and applications while moving, using portable devices and wireless networks.

Key constraints of mobile computing: limited battery life, limited processing power, small screen size, variable bandwidth, and intermittent connectivity.

The three-tier architecture of mobile computing: presentation tier (client device), application tier (middleware/application server), and data tier (database/back-end).

Mobile devices are classified by form factor and capability: smartphones, tablets, wearables, embedded sensors, and laptops.

Wireless communication media include radio waves (Wi-Fi, cellular, Bluetooth), infrared, and microwave; radio is the most common due to range and non-line-of-sight operation.

Mobility types: user mobility (person moves with device), device mobility (device moves between networks), and session mobility (session persists across devices).

Context awareness in mobile computing uses sensors (GPS, accelerometer, light, proximity) to adapt services to location, time, and user activity.

Challenges of mobile computing include security, privacy, energy management, heterogeneity of devices and networks, and seamless handoff.

Cellular generations: 1G analog voice, 2G digital voice + SMS, 3G mobile data, 4G LTE all-IP broadband, 5G enhanced mobile broadband and low-latency IoT.

IEEE 802.11 (Wi-Fi) uses CSMA/CA for medium access; stations contend for the channel and use acknowledgment frames to detect collisions.

Bluetooth (IEEE 802.15.1) operates in the 2.4 GHz ISM band using frequency-hopping spread spectrum; it forms piconets with one master and up to seven active slaves.

Mobile IP allows a mobile node to maintain its home IP address while visiting foreign networks; it uses home agent, foreign agent, care-of address, and tunneling.

Handoff (handover) is the process of transferring an active connection from one base station or access point to another; hard handoff breaks before making, soft handoff makes before breaking.

Wireless network security: WEP is deprecated; WPA2 uses AES-CCMP; WPA3 uses SAE for stronger authentication and forward secrecy.

TCP performance over wireless is affected by packet loss misinterpreted as congestion; solutions include split TCP, snoop TCP, and link-layer retransmission.

Mobile ad hoc networks (MANETs) are infrastructure-less, self-configuring wireless networks where nodes act as routers; routing protocols include AODV and OLSR.