Quick Summary of Different Generations

First generation (1G).
AMPS/ETACS handsets in the 1980s required low-cost microcontrollers to manage the allocation of multiple RF (radio frequency) channels (833 × 30 kHz channels for AMPS, 1000 × 25 kHz channels for ETACS) and low-cost RF components that could provide acceptable performance at 800/900 MHz.

Second generation (2G).

GSM, TDMA, and CDMA handsets in the 1990s required low-cost digital signal processors (DSPs) for voice codecs and related baseband processing tasks, and low-cost RF components that could provide acceptable performance at 800/900 MHz, 1800 MHz, and 1900 MHz.

Third generation (3G).

W-CDMAand CDMA2000 handsets require—in addition to low-cost microcontrollers and DSPs—low-cost, low power budget CMOS or CCD image sensors; low-cost, low power budget image and video encoders; low-cost, low power budget memory; low-cost RF components that can provide acceptable performance at 1900/2100 MHz; and high-density battery technologies.

Beyond 3G systems

While HSPA and HRPD systems were being developed and deployed, IEEE 802 LMSC (LAN/MAN Standard Committee) introduced the IEEE 802.16e standard for mobile broadband wireless access. This standard was introduced as an enhancement to an earlier IEEE 802.16 standard for fixed broadband wireless access. The 802.16e standard employed a different access technology named OFDMA (orthogonal frequency division multiple access) and claimed better data rates and spectral efficiency than that provided by HSPA and HRPD.

Although the IEEE 802.16 family of standards is officially called WirelessMAN in IEEE, it has been dubbedWiMAX (worldwide interoperability for microwave access) by an industry group named theWiMAX Forum. The mission of theWiMAX Forum is to promote and certify the compatibility and interoperability of broadband wireless access products. The WiMAX system supporting mobility as in IEEE 802.16e standard is referred to as MobileWiMAX. In addition to the radio technology advantage, MobileWiMAX also employed a simpler network architecture based on IP protocols.

The introduction of Mobile WiMAX led both 3GPP and 3GPP2 to develop their own version of beyond 3G systems based on the OFDMA technology and network architecture similar to that in MobileWiMAX. The beyond 3G system in 3GPP is called evolved universal terrestrial radio access (evolved UTRA) and is also widely referred to as LTE (Long-Term Evolution) while 3GPP2’s version is called UMB (ultra mobile broadband). It should be noted that all three beyond 3G systems namely Mobile WiMAX, LTE and UMB meet IMT-2000 requirements and hence they are also part of IMT-2000 family of standards.