EDGE_Radio for handsets

yxy7826

dio Design for EDGE Handsets[52RD.com]
From Silicon laboratories Inc.[52RD.com]
A basic introduction of Radio design for EDGE mobile phones.
【文件名】:06714@52RD_EDGE_Radio_WP.pdf
【格　式】:pdf
【大　小】:314K
【简　介】:
【目　录】:

aoli

不错，讲的挺详细的。

Raining

[em10]

mwo1974

Introduction
The cellular handset is evolving into a data-oriented device. Data-oriented applications
including digital photography and video, mobile gaming and mobile commerce are
becoming increasingly mainstream. Handset features that were once reserved for highend
handsets such as color screens, digital cameras and stereo sound are now
becoming standard features on mid-range handsets. To support increasing amounts of
data traffic, network operators are implementing new high-speed data technologies
such as Enhanced Data-rates for GSM Evolution (EDGE ) onto the GSM network.
EDGE is being implemented as an extension of existing GSM/GPRS service. To permit
high-speed data, a new modulation called 8-PSK must be supported in addition to the
existing GMSK modulation used for GSM/GPRS. However, to ensure backwards
compatibility, EDGE radios must support the capability for 8-PSK modulation with no
compromise to GSM/GPRS performance.
Various EDGE radio architectures have been proposed to support both GMSK and 8-
PSK modulation. Radios based on polar loop or polar modulation promise to provide
high-power added efficiency (PAE) at the expense of additional calibration and
complexity required to support the power control feedback loop. Alternative radios
support EDGE by adding a linear transmitter for 8-PSK modulation to an existing
GSM/GPRS transceiver. This approach has the benefit of supporting 8-PSK modulation
while at the same time preserving excellent GSM/GPRS performance.
EDGE Modulation and Data Rates
In addition to supporting the legacy GMSK modulation required for GSM/GPRS service,
EDGE introduces a new modulation called 8-PSK to provide high-speed data. Unlike
GMSK that encodes one bit per symbol, 8-PSK encodes three bits per symbol within the
same symbol period. Therefore, the maximum data rate for EDGE is approximately
three times higher than for GSM/GPRS. The channel bandwidth, network slot structure,
and timing are the same for both GMSK and 8-PSK modulation.
GMSK and 8-PSK Modulation
Figure 1 shows sample I/Q constellations and transmitter power profiles for GMSK and
8-PSK modulation. GMSK modulation encodes one bit per symbol by accumulating a
phase within a symbol period that is either +90 or –90 degrees offset from the carrier.
To suppress high-frequency components, the phase accumulation is smoothed with a
Gaussian filter defined by the 3GPP standard [1]. In the I/Q plane, the phase variation
creates a trajectory around a circle of unit amplitude, corresponding to pure phase
modulation. The transmitted signal amplitude is constant during the burst..........