1 / 23

Wireless Wide Area Networks 3G/4G - mobile phones

Wireless Wide Area Networks 3G/4G - mobile phones. Multiplexing (collection of schemes to transmit multiple signals simultaneously). FDM - Frequency-Division Multiplexing - analog, modulated to a fixed frequency band, channel.

lonna
Download Presentation

Wireless Wide Area Networks 3G/4G - mobile phones

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Wireless Wide Area Networks 3G/4G - mobile phones

  2. Multiplexing (collection of schemes to transmit multiple signals simultaneously) • FDM - Frequency-Division Multiplexing - analog, modulated to a fixed frequency band, channel. • TDM - Time-Division Multiplexing - same frequency in alternating time slices, each channel makes full use of the bandwidth, GSM and D-AMPS use TDM • CDM - Code-Division Multiplexing - makes better use of frequency than FDM and TDM. Signals are transmitted on the same frequency and same time, but have a unique code to identify itself. CDMA use CDM, of course.

  3. Spread Spectrum (signals in a wider band with low power density (power per frequency), appears as background noise to others than the receiver. Used in CDMA and WLANs.) • DSSS - direct-sequence spread spectrum - a chipping sequence code (digital modulation) creates a chipping sequence (shorter signals than original bits) that is modulated with a carrier signal (radio modulation). 802.11b, CDMA uses DSSS. • FHSS - frequency-hopping spectrum - first modulates to narrowband signals, then a second modulation uses a hopping sequence of frequency to send the radio signal. Bluetooth uses FHSS. • OFDM - orthogonal-frequency-division multiplexing - uses multiple subcarriers in parallel to transmit data. The subcarriers are orthogonal in that they are modulated with their own data independently. It is used in ADSL, 802.11a/g wireleess LANs, and WiMax. • DSSS and FHSS can be multiplexed by CDM.

  4. Cellular generations (from the point of view of using multiplexing and spread spectrum) • First generation: FDMA (FDM Access), where each cell supports a number of channels of equal bandwidth, and each cellphone uses two channels (one up and another down). • Second generation in two groups: • TDMA (TDM Access): GSM (Global System for Mobile) and D-AMPS (IS-136). GSM is basically circuit-switching based, but GPRS (general packet radio service) was added to support data: SGSN (serving GPRS support node) and GSSN (gateway GPRS support node). • CDMA (CDM Access): CDMA comply with IS-95 (also known as cdmaOne). Uses DSSS combined with CDM. Designed by Qualcomm Inc, which holds IP over CDMA.

  5. Cellular bands for AMPS (1G) an analog cellular phone system using FDMA

  6. AMPS reverse communication band

  7. Second-generation cellular phone systems

  8. D-AMPS (IS-136, is a digital cellular phone system using TDMA and FDMA)

  9. GSM bands (digital cellular phone system using TDMA and FDMA)

  10. GSM system (each voice channel is digitized and compressed to a 13kbps digital signal)

  11. GSM frame and frequency bands

  12. IS-95 forward transmission (digital cellular phone system using CDMA/DSSS and FDMA)

  13. IS-95 reverse transmission

  14. IMT-2000 radio interfaces (3G) GSM GPRS&EDGE IMT (International Mobile Telecommunication)

  15. GSM (3G) • 3G data rate requirements • 144 kbps at driving speed • 384 kbps outside stationary speed • 2Mbps for indoors speed • GSM + GPRS + EDGE achieve 3G • GPRS added to allow dynamic use of multiple channels and speeds up to 115 kbps (2.5 G) • EDGE (Enhanced Data Rates for Global Evolution) added to allow speeds up to 384 kbps • GSM uses SIM (subscriber identity module) cards to identify user, network, etc.

  16. Cellular technology evolution

  17. Differences between Wi-Fi and  3G

  18. New generation: 4G • Introduced around 2010 • Typical speed 3 Mbps to 5 Mbps: 10 times over 3G • Designed to give at least 2 Mbps download speeds to mobile customers • Eventually, 100 Mbps to mobile users and 1 Gbps to stationary users • Designed to give at least 100 Mbps download speeds to fixed customers • Sufficient for high-definition video • Runs over IP • Wikipedia data rate comparison

  19. 4G Technologies • WiMAX (Worldwide Interoperability for Microwave Access) • Based on 802.16 standard. • WiMAX forum promotes it • 802.16m will eventually provide 100 Mbps to mobile users and 1 Gbps to stationary users. • Clearwire is a pioneer in its deployment, now also planning to offer LTE Advanced • Long Term Evolution (LTE) • The 4G technology that most cellular carriers have adopted. • Provide 14 Megabits speeds • LTE Advanced will provide 100 Mbps to mobile users and 1 Gbps to stationary users.

  20. Convergence of Wi-Fi and cellular technologies ISP 802.11 Cellular Carrier 3G or 4G 802.11 • 3G and 4G Mobile Smartphones and tablets • Often can connect directly to an 802.11 WLAN for service • Typically faster speeds than cellular for data • Cellular companies like offloading flat-fee subscribers to the WLAN • Some Smart Phones Can Act as 802.11 Access Points • Several 802.11users can share its capacity.

  21. Mobile computing growth

  22. Mobile computing technologies • Sales by OS (Market Share %) • Sales by OS (Thousands of Units) *Blackberry OS migrating to QNX in 2012 Source: Worldwide Mobile Communications Device Open OS Sales to End Users by OS, Table 1 (Gartner, April 2011)

  23. Mobile computing links (a few) • My on-going series • UB OTS Lab App • Creating Android Apps • Creating iOS Apps • 16 essential Android apps for IT Professionals • The 25 Best iPhone Apps from PC Magazine • The 25 Best Android Apps from PC Magazine • Engadget • C|Net news • Zdnet • PC World

More Related