Cisco Cisco Catalyst 6000 Multilayer Switch Feature Card MSFC2 White Paper

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Introduction

While there have been great advances made in the speed and ease of implementation of Wi-Fi networks, the

basic nature of radio frequency (RF) is generally unchanged. Increasing the number of users who can access the

WLAN in a small physical space remains a challenge. The steps and process for a successful high user density

WLAN design that can be proven, implemented, and maintained using

Cisco’s Unified Wireless Network

architecture is detailed. It includes these general steps:

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Plan: Determine application and device requirements such as bandwidth, protocols, frequencies, service

level agreement (SLA), etc.

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Design: Determine density, cell sizing, antennas, coverage, site survey, etc.

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Implement: Install, test, tune, establish baseline, etc.

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Optimize: Monitor, report, adjust, review baseline for SLA.

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Operate: Cisco Wireless Control System (WCS) monitoring, troubleshooting tools, capacity monitoring and

reporting tools, etc.

The general concepts underlying high-density Wi-Fi design remain true for many environments. But it is important

to note that the content and solutions presented here will not fit every WLAN design scenario. Rather, the intent of

the guide is to explain the challenges in WLAN design for high-density client environments and to offer successful

strategies so that engineers and administrators understand them and are able to articulate the impact design

decisions will have.

Target Environmental Characteristics for WLANs in Higher Education Environments

High-density WLAN design refers to any environment where client devices will be positioned in densities greater

than coverage expectations of a normal enterprise deployment, in this case a traditional, carpeted office. For

reference, a typical office environment has indoor propagation characteristics for signal attenuation. User density

is the critical factor in the design. Aggregate available bandwidth is delivered per radio cell, and the number of

users and their connection characteristics (such as speed, duty cycle, radio type, band, signal, and SNR)

occupying that cell determines the overall bandwidth available per user.

A typical office environment, Figure 1, may have APs deployed for 2,500 to 5,000 square feet with a signal of -67

decibels in millowatts (dBm) coverage and a maximum of 20 to 30 users per cell. That is a density of one user

every 120 square foot (sq. ft.) and yields a minimum signal of -67 dBm.

Figure 1. Typical Office WLAN