1. 4-G Cellular Systems

2. 2 What is 4-G? High data speed: 100 Mbps to 1Gbps anywhere, anytime Enable voice, data and streamed multimedia (enough speed for streaming HDTV, digital video broadcasting, video chat, …) with low latency Based on TCP/IP (Internet protocol) only (3-G systems use both circuit switched and packet switched networks)

3. 3 Technologies used in 4-G It uses OFDMA and other new technologies (Single Carrier FDMA, Interleaved FDMA, Multi- carrier CDMA, …) instead of CDMA, which is used by all 3-G systems. The problem with CDMA is it cannot adjust spectrum allocated to users (all users get the same amount of spectrum). Also, the highest data rate is limited. MIMO (Multiple-Input Multiple-Output) antennas New modulation techniques (64QAM: Quadrature amplitude modulation)

4. 4 MIMO Multiple antennas used by the transmitter and the receiver Parallel streams are transmitted simultaneously by those antennas Data rate is increased (if 4 pairs of antennas are used, the data rate can be increased by 4 times) Can also increase reliability

5. 64QAM The amplitude of two waves, 90 degrees out-of-phase (in quadrature) are changed (modulated) to represent the data signal. Phase modulation is a special case of QAM. 5

6. 6 4-G Systems WiMax UMB (Ultra Mobile Broadband) LTE (Long Term Evolution)

7. 7 UMB To bring CDMA2000 (US standard) to 4-G Based on Internet (TCP/IP) networking Peak rates of up to 280 Mbps Support handoffs with CDMA2000 and 1xEV-DO Use OFDMA In Novemver 2008, Qualcomm, UMB’s lead sponsor, announced it was ending development of the technolgy, favoring LTE instead.

8. 8 LTE (Long Term Evolution) To bring UMTS (Europe 3G) to 4-G Uses OFDMA for downlink with a maximum of 2048 subchannels Download rate: 326 Mbps for 4x4 antennas for every 20 MHz of bandwidth Uses Single Carrier Frequency Division Multiple Access (SC-FDMA) for uplink. A problem with OFDMA is the high peak-to-average power ratio. SC-FDMA can provide higher power efficiency which is crucial for mobile stations. Uses 64QAM modulation Uses MIMO and beam forming with up to 4 antennas All IP Network

9. LTE (cont.) Downlink peak data rates 300Mbps per 20MHz of spectrum and uplink data rates, 75 Mbps per 20 MHz Supports at least 200 active users per cell in 5MHz 9

10. Comparison of LTE and WiMax Similar technologies WiMax is already in the market in Pakistan and Sprint Nextel and Clearwire has deployed it in the US (first in Baltimore this year). LTE is still under standardization. LTE is the upgrade for GSM network that accounts for over 85% of all mobile subscribers in the world. The existing GSM/GPRS/EDGE operators can use their current infrastructure (base station towers) with new equipment to upgrade to LTE. A WiMax operator has to start from scratch. AT&T and Verizon will roll out LTE in 2011/2012. Qualcomm supports LTE. 10