CDMA2000

CDMA2000 400 MHz, 800 MHz, 900 MHz, 1700 MHz, 1800 MHz, 1900 MHz, and 2100 MHz • Compatible with the cdmaOne standard A set of 3G communication CDMA2000 standards CDMA2000 1x (2.5G) CDMA2000 1xEV-DV (evolution for high speed integrated data and voice) (3G) 614 kbps CDMA2000 1xEV-DO (evolution for data optimized (3G) 2.05 Mbps CDMA2000 3x (3G) Three 1.2288 Mbps channels

CDMA 2000 Access is random, uses the slotted Aloha protocol Chipping rate 1.2288 Mchip/s Short PN code, Long PN code and Walsh code Multirate transmission Low data rate signals used for voice and messages High data rate signals for pictures, videos, and large packets

4G Technologies 100 Mbps for high mobility communication (such as from trains and cars) 1 Gbps for low mobility communication (such as pedestrians and stationary users) Facilities such as ultra –broadband Internet access, IP Telephony, gaming services, and streamed multimedia may be provided to users.

4G Technologies Pre-4G Technologies such as mobile Wi-Max – 2006. 4G Technologies such as Long Term Evolution (LTE) – 2009. CDMA radio technology used in 3G is replaced by OFDM

OFDM Orthogonal Frequency Division Multiple Access File transfer at 10 Mbps • High resolution 1024 × 1920 pixel hi-vision picture transfer at 24 Mb/s • High resolution video transfer Mobile multimedia services Special type of Multi-carrier Modulation

Multi-carrier Modulation It splits the high bit rate stream into many lower bit rate streams, each stream being sent using an independent carrier frequency. N symbols/S have to transmitted, each subcarrier transmits n/c symbols/S where c – number of subcarriers OFDM – orthogonal carriers are used.

OFDM Multiple carriers use mutually orthogonal codes, which enables separation of carriers in case of multi-path transmissions and interference of signals. • All channel carriers (adjacent channel codes) are using different but mutually orthogonal codes Each channel carrier has distinct amplitude (power level) and may have a time guard.

Three most important characteristics of OFDM High spectral efficiency • Strong resiliency to RF inter symbol interferences • Lower multi-path distortions

OFDM Also called COFDM (code orthogonal frequency division multiplexing) • Also called spread-spectrum based multicarrier or discrete multi-tone modulation 0s are transmitted as + 1s and 1s are transmitted as –1s for signal mapping as per 3GPP specifications The codes themselves may be from a different set of orthogonal codes • The only condition put on them is that they should all be orthogonal with no cross correlation

OFDM Digital Signal Processors are used to perform modulation and demodulation in OFDM systems.

Applications OFDM technology is used in wireless LANs for point-to-point transmission and for multicasting. OFDM is also used in Digital Audio Broadcasting (DAB) and Digital Video Broadcasting (DVB) which enables users to watch TV on their mobile devices. OFDM is also used in asymmetric digital subscriber line (ADSL) which is used for broadband Internet over telephone lines.

Techniques in OFDM Wideband OFDM (WOFDM) Flash-OFDM (fast low-latency access with seamless handoff OFDM) MIMO-OFDM (Multiple Input, Multiple output OFDM) VOFDM (Vector OFDM)

WOFDM A technique in which spacing between multi-carrier channels is made large • Therefore, any frequency errors between the transmitter and the receiver do not affect system performance

Flash-OFDM Based on the FHSS spectrum • Fast-hopped OFDM

MIMO-OFDM A technique in which multiple antennae are used for inputs and outputs • Provides broadband wireless access (BWA) and performs well in multiple nonline- of-sight multiple-path environments

VOFDM Technique based on MIMO-OFDM • Developed by Cisco Systems, Inc