WLAN system trends and the implications for WLAN RFICs

Abstract

Abstred -Sir trends in WLAN systems are described. For each trend, implications for the WLAN RFlCs are described. The six trends include increasing levels of integration, dual band operation. large percentage tuning h g e s , ver). high data rates, long range capability, and PA dlicicncy cnhanrements. Potential solutions to these issues $re examined. I new extended range mode, Tx power control $).stem, and amplifier emciency enhaneement approach is presented. Regulatory and performance requirements are described. Radio architecture, RF circuit design techniques, and system solutions are all described. Several examples are drawn from a siagle-cbip, dual-band, CMOS transceiver for IEEE 802.11a/h/g sireless LAN designed at the author's company. Index Terms -Wireless LAN, power amplifiers, OFDII, 802.11, power control, hllMO, direet conversion. Fig. I. Comparison of direct conversion and two step predistortion, convex optimization. conversion radios.%-= syynth.

An OFDM MIMO Transmitter for Wireless Gigabit with Advanced Multimedia (WIGWAM)

“…a 64QAM modulated 802.11a/g signal has a crest factor of 17 dB requiring typically 8.5 dB output power backoff in a CMOS transceiver to fulfill the specification. An idealized transfer characteristic of a perfectly linear limiter that hardly saturates at P sat would require only 5.5 dB backoff [4]. This corresponds to an increase of output power by 3 dB or increasing the transmitter power efficiency with a modulated OFDM signal by 100%.…”

A WLAN/WMAN Dual Mode Transceiver System for Indoor/Outdoor Application

“…The terminals for emerging 4G systems have to satisfy high data rate and high mobility requirements and operate in multimode/band configurations. WLAN (Wireless local area network), IEEE 802.11a standard for fixed broadband wireless communication, have shown impressive growth and is becoming a popular method for wireless internet connection and other applications [1][2][3]. However, WLAN lack in mobility and can be used only in small area around 'hot spot'.…”

A 5-GHz highly integrated receiver front-end

“…An alternative cost-effective heterodyne architecture was proposed to achieve a high level of integration, while avoiding the drawbacks of the direct-conversion [1]. It exploits a sliding-IF rather than a traditional fixed-IF approach.…”