The Effects of Adjacent Channel Rejection 射频临道抑制比的解释ACR.pdf

SPLY005 – November 2003

White Paper

Overview ................................................................................................................................ 2

What’s at Stake? ................................................................................................................... 2

Receiver Design for ACR ..................................................................................................... 5

802.11 Receiver Architectures............................................................................................. 7

Bluetooth™ and WLAN Coexistence Issues ...................................................................... 9

In-Band Interference and Link Budgets............................................................................ 13

In-Band Signal-to-Interference Analysis........................................................................... 15

The Effects of Power Control on In-Band Interference ................................................... 16

Anticipating Interference Issues ....................................................................................... 17

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technologies in the same unlicensed spectrum is rapidly increasing the radio frequency (RF)

interference for Wi-Fi® (802.11) products, threatening the data throughput performance of

wireless local area networks (WLAN). At the same time, the market is demanding higher data

throughput rates for new WLAN applications like multimedia audio and video, streaming media,

voice over WLAN, and others that require quality of service (QoS) capabilities and low packet

interference in the environment for WLAN equipment, the design of radios and digital filtering

technology in both the 2.4 GHz and 5.x GHx unlicensed bands has come to the attention of

manufacturers, system designers, integrators and the Federal Communications Commission

(FCC). In fact, when the FCC released an additional 250 MHz of spectrum for 802.11 WLANs

starting at 5.4 GHz, it noted that regulatory changes soon may be needed in WLAN's crowded

band of the spectrum. The FCC may soon issue a "Notice of Inquiry" (NOI) that would gather

in this spectrum.

What's at Stake?

• Corporate/enterprise deployments

• Dense commercial hot-spot deployments (strip malls, etc.)

• Residential apartment building deployments

• High density urban deployments

The performance of WLANs can be hampered by a number of sources of interference, including

the following non-802.11 equipment:

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• Spurious RF noise in integrated devices, handsets and PDAs with multiple wireless

• Wideband 5 GHz equipment for the emerging "world band" requirements

802.11 system's RF sub-system and digital filtering can greatly affect the performance of the AP

means perfect. Indeed, the signals from 802.11 radios generate some amount of energy outside

band as 802.11. Although filtering is usually done to minimize RF interference from adjacent

SPLY005