C H A P T E R 3

Surveying for Cell Capacity and Channel Re-Use

This chapter describes how to perform a site survey to design a wireless LAN for cell capacity and channel re-use.

Survey Design for Cell Capacity

Cisco recommends that you install enough access points to provide all users with quality calls. Maintaining high call quality might require small coverage cells that limit the number of calls per access point to 7 to meet the QBSS level on access points below 35. With a recommended RSSI level of 20 dB throughout the RF network, the access point transmit powers could be as low as 20mW, with low-gain antennas on the access points. You should consider these design factors to ensure adequate capacity and coverage:

•removing interfering devices

•configuring older 802.11 devices to lower transmit power

•configuring older 802.11 devices to the highest possible data rate

When you configure the access points for higher data rates and lower transmit power, the cell coverage from the access point becomes smaller. However, if you adjust the access points for high data rates and low transmit power but you do not make similar adjustments on the clients, the cell might be unbalanced, as in Figure 3-1, except that the client signal exceeds the access point signal.

Figure 3-1 Unbalanced Cell Due to Mismatched Transmit Power and Data Rate Settings

5mW

100mW

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Depending on the configurable and non-configurable parameters of the client, it might continue to transmit packets at a 1 Mbps data rate. The transmit coverage of a client could be 400 feet when the transmit coverage of the access point is 100 feet. This mismatch could affect the call capacity and QBSS of an access point several cells away from the access point to which the client is associated.

Site Survey Guide for Deploying Cisco 7920 IP Phones

 

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Cisco Systems 7920 manual Survey Design for Cell Capacity, Surveying for Cell Capacity and Channel Re-Use
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7920 specifications

Cisco Systems, a leading player in the global networking and communications technology sector, designed the Cisco 7920 Wireless IP Phone for mobile professionals seeking seamless connectivity in various environments. Primarily aimed at enhancing communication within enterprise settings, this wireless device offers a plethora of features that cater to the specific needs of businesses.

At the core of the Cisco 7920 is its robust wireless functionality. It operates on IEEE 802.11b/g wireless protocols, allowing users to connect effortlessly to Wi-Fi networks. This flexibility enables employees to communicate effectively from various locations within an office space, promoting mobility and collaboration without being tethered to a desk.

The ergonomic design of the Cisco 7920 prioritizes user comfort. Its lightweight casing and intuitive button layout ensure that users can navigate the interface with ease. The device is equipped with a vibrant color display, allowing for clear visibility of caller ID, call status, and menu options, enhancing the user experience further. Additionally, the handset supports a wide variety of languages, making it suitable for global teams.

In terms of features, the Cisco 7920 is loaded with advanced capabilities. It supports voice over IP (VoIP), delivering high-quality audio and ensuring reliable communication. Users benefit from features like a contextual menu, call hold, transfer, conference calling, and voicemail access on the go. The phone also offers a wide range of ringtones, allowing customization to suit personal preferences or company branding.

Security is a crucial aspect of modern telecommunications, and the Cisco 7920 does not fall short. It incorporates industry-standard security protocols such as Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA), safeguarding communications from potential threats.

Moreover, the Cisco 7920 integrates seamlessly with Cisco Unified Communications Manager, enabling centralized management and control. This integration ensures that IT departments can deploy, manage, and troubleshoot devices efficiently, streamlining operations while ensuring optimal performance.

In conclusion, the Cisco 7920 Wireless IP Phone stands out as a versatile communication tool designed for the fast-paced workplace. Its combination of wireless connectivity, ergonomic design, advanced features, and robust security makes it an essential accessory for businesses looking to elevate their communication strategies. With its established reputation, Cisco continues to support companies in achieving seamless connectivity and effective collaboration.
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