Cisco Systems 7920 manual Ideal Wipt Environment, 67dB 86dB Channel

Chapter 1 Overview

Recommendations for Successful VoIP Surveys

difference in transmitter power and receiver sensitivity that matters because the gain of an antenna is reciprocal. To verify the cell coverage edge of –67 dBm while the client is actively sending and receiving voice size packets, check the access point’s Station Information and Status page for a dBm value of –67 dBm or higher.

Figure 1-3 Transmit Power Imbalance

5mW

100mW

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The Ideal WIPT Environment

Figure 1-4shows the ideal WIPT cell with the recommended cell edge signal strength value of -67 dBm at an 11-Mbps data rate and the recommended same-channel separation of 19 dBm at an 11-Mbps data rate. The two yellow cells have a cell edge of –67 dBm. The measured overlap of a channel should not exceed –86 dBm (from the center of the measured cell to the edge of the neighboring cell of the same channel). This is the value of –67 dBm plus the 19 dBm for separation. Keeping the separation at 19 dBm between same-channel cells produces a cell with minimal throughput degradation because of media contention. This helps maintain up to 7 good-quality WIPT calls in a cell.

Figure 1-4 Ideal WIPT Environment

A typical deployment showing a 15-20% overlap from each of the adjoining cells.

Provides almost complete redundancy throughout the cell

Channel

1

Channel

11

The radius of the cell should be:

67 dBm

	The separation of
	same channel cells
	should be:
	19 dBm
	7920 RSSI=20
67dB	86dB

Channel

6

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Site Survey Guide for Deploying Cisco 7920 IP Phones

OL-6315-01 1-5