User's Manual

ManualsBrandsMotorola ManualsNetworkingMC-802

Installing Motorola MC-802 Wireless WallPlate

The MC-802 Wireless WallPlate is a new addition to the PowerBroadband product family. This

application note details specific topologies and best practices used for the installation of the

Wireless WallPlate. To set the proper context, we’ll start with a short introduction of the T3

PowerBroadband system. Key concepts used throughout the document are covered in Appendix

A. Best practice recommendations include a limited site survey procedure to determine

installation density.

T3 PowerBroadband System

The T3 system from Motorola is designed primarily for hospitality, but useful in any high density

MDU type installation. The T3 PowerBroadband Switch is installed in the central phone room of a

hotel or MDU, where it is cross connected onto the existing telephone wiring. The centrally

installed T3 PowerBroadband Switch has 25 ports for downstream CPEs, and 2 x GigE uplink

ports.

Two different types of remote CPEs are supported. The CPEs are installed in a hotel guest room

or any RJ11 jack within the MDU. The CPEs are designed as a wall plate form factor, and draw

operating power over the same telephone wire pair as broadband backhaul. Due to the form

factor, the name “WallPlate” is used to describe the CPE.

m2 WallPlate

The m2 WallPlate is a managed, Ethernet-only device. It has two 10/100Mb Ethernet

ports to connect access devices. 802.1Q VLANs and QoS can be managed throughout

the system, from the 25-port switch to each wall plate port.

MC-802 Wireless WallPlate

The Wireless WallPlate is just what it sounds like. It is a line-powered WallPlate with an

integrated 802.11b/g radio. The Wireless WallPlate has the same two 10/100Mb

Ethernet ports as the m2 WallPlate. All configuration, status and statistics for the

Wireless WallPlate are provided by the centrally installed T3 Switch.

Key features:

• Line power up to 600 meters* for the m2 WallPlate, and 300 meters

for the MC-802 Wireless WallPlate. Line power is transparent to and

compatible with analog telephone service on the same wire

• One wire pair

• Optimized for IPTV and other advanced networking

*600m is the limit of line power. If using an optional external power supply, T3 will deliver

broadband up to 1500m

The T3 system is comprised of the following components. In addition to the primary products

listed, filters are required for extra telephones that share the same wire pair.

Motorola, Inc Page 1 of 12

Summary of content (12 pages)

PAGE 1
Installing Motorola MC-802 Wireless WallPlate The MC-802 Wireless WallPlate is a new addition to the PowerBroadband product family. This application note details specific topologies and best practices used for the installation of the Wireless WallPlate. To set the proper context, we’ll start with a short introduction of the T3 PowerBroadband system. Key concepts used throughout the document are covered in Appendix A.
PAGE 2
• • • Name: Motorola P/N: Model: T3 PowerBroadband Switch, RoHS 558975-001-00 45225 • • • Name: Motorola P/N: Model: m2 Ethernet WallPlate, RoHS 549478-001-00 45101 • • • Name: Motorola P/N: Model: MC-802 Wireless WallPlate, RoHS 557925-001-00 45010 T3 PowerBroadband Switch and m2/MC-802 WallPlates TABLE OF CONTENTS Installation Routine.............................................................................................3 Example Lite-Site Survey ............................................
PAGE 3
Installation Routine The goal of the installation can be stated relative to received signal strength (RSSI): • • -70dBm signal strength or better in every room Maximum of three co-channel cells within the carrier detect range Perfect non-overlapping cell coverage is impossible to achieve. Read Appendix A for a description of the carrier detect range and its effect on media access. The network architect can control three variables when deciding where and how to install the Wireless WallPlate network.
PAGE 4
The goal of the WallPlate site survey is to determine the average RSSI loss through one room/wall combination Provisioning the WallPlates • Order the number of WallPlates according to the RSSI loss through one room/wall. If the floor material is the same as the walls e.g. concrete, then the vertical loss will be similar (usually +3dB to +6dB). Offset the installation with each floor so that WallPlates are not stacked vertically above one another.
PAGE 5
Example Lite-Site Survey Many hotels are built with mirror image rooms to speed the construction time. The example below was taken from a real 250 room hotel constructed of concrete block on all interior and exterior walls.
PAGE 6
Location Transmitter RSSI -28dBm Loss 42dB A a B C D -32dBm -60dBm -55dBm -83dBm -80dBm 4dB 32dB 27dB 55dB 52dB Note Antenna to air conversion loss. Measured at 1m using integrated Intel Pro2200B/G in Dell Laptop. Same room, with AP mounted 12” from floor Down one floor One room over Across the hall, over one room Two rooms over Note some interesting results: 1. We can predict the measured RSSI three rooms over would be -105dBm, well below the carrier detect range. 2.
PAGE 7
Example Installation E x a m p l e O n e : Ro o m L o s s = 2 0 d B Hotels generally use dense wall material to reduce audible noise from one room to another. Concrete is a common material. 20 to 25dB RF loss can be measured through concrete hotel walls, but actual results may vary. The worst case would be a client PC sitting approximately midway between two WallPlates on the same floor. From this location, the client would be within the carrier detect range of multiple WallPlates.
PAGE 8
RF Media Access The client wireless driver will connect with the WallPlate that has the strongest RSSI. Regardless of which WallPlate is selected by the client driver, the co-channel interference will be one other WallPlate, very low co-channel interference and well within the bandwidth of the RF medium. Redundancy Five total WallPlates are within -70dBm of the client. Thus, if one WallPlate fails, the client will always maintain a high datarate connection to the network.
PAGE 9
Transmit Power Adjustment In this case, we reduce the transmit power of all WallPlates by 6dBm. Note the resulting RSSI changes: WallPlates A, G, C and I fall below the carrier detect range and will not present cochannel interference with the client.
PAGE 10
A pp en di x A Media Access Control 802.11 wireless devices are half-duplex; meaning they cannot transmit and receive simultaneously. Access to the media is controlled by carrier detect media access - listening on the specified frequency, and transmitting in a time when no other signal is present. Using carrier detect many devices can share the same RF medium. Adding CTS/RTS further increases the number of co-channel devices; although CTS/RTS itself reduces the total bandwidth available to the client.
PAGE 11
The material used in walls and floors can vary from one property to another. For example, different chemical formulations of concrete can cause loss variations up to 5dB. The following chart is based on RF engineering studies and can be used as a general guide. Material Concrete block Red Brick Drywall Loss (dB) 15 - 20 15 – 25 3–6 + Room (dB) 6 6 6 = RoomLoss (dB) 21 – 26 21 – 31 9 - 15 Tools Many software site survey tools are readily available for a charge or free.
PAGE 12
Deviations and Exceptions As always, there will be exceptions. For example, a hotel may not use the same material between all rooms. It could be that concrete is used every four or five rooms; with drywall between the concrete walls. This can be very good for proper signal attenuation, but some upfront thinking is required. In general, using the RoomLoss method with an Install Time adjustment will lead to faster or no site surveys.