MMDS or Wireless Cable TV, MVDS

The Wireless Access business unit designs and markets integrated customer premises solutions for Wireless Cable (MMDS), broadband wireless multimedia access and wireless data traffic. 

 

Wireless Internet Access via two way MMDS

Customer Premise Equipment CPE for Wireless Cable (MMDS), broadband wireless multimedia access and wireless data traffic. 

Frequency range: 2.1 GHz - 2.7 GHz
Operation: Duplex

CPE Transceiver

MMDS Transmitter

 

Estimation of the RF MMDS Path

Source: http://www.iec.org/online/tutorials/wire_broad/topic12.html

Assumption:

Analog MMDS Transmitter
Power/sync in dBm

Please remember:

 dBm 50 Ohm Power
0 dBm 1 mW
3 dBm 2 mW
6 dBm 4 mW
7 dBm 5 mW
9 dBm 8 mW
10 dBm 10 mW
20 dBm 100 mW
30 dBm 1 W
40 dBm 10 W
43 dBm 20W
50 dBm 100W

MMDS Path Engineering: The Math*

Txp = transmitter output power in dBm

CL = channel combiner losses in dB

TLL = total transmission line loss in dB

TAG = transmit antenna gain in dBi

PL = free space path loss in dB = 96.6 +20 Log (frequency in GHz) + 20 Log (distance in miles)

RAG = receive antenna gain in dBi

BDCG = block down converter gain in dB

RLL = total receive line loss in dB

NF = thermal noise floor (-108 dB)

nf = noise figure of receive system, down converter (2.6 dB typical)

FM = fade margin (15 dB typical)

The critical design factor for a digital system is the required signal-to-noise ratio (SNR) of the receiver. For this case, 25 dB S/N. Fade margin is an estimated value that will vary at each site. Factors that can contribute to fade include heavy rain, multipath, terrain, and foliage blockage.

Analog System  50dB S/N

Signal Strength Link Budget

Txp - CL - TLL + TAG - PL - FM + RAG + BDCG - RLL = signal strength @ rx site in dBm

S/N Link Budget

Txp - CL - TLL + TAG - PL - FM + RAG - nf - NF = S/N @ rx site in dB

Note that this calculation applies for a modem with 2-MHz channels and 4.5 dB transmitter additional headroom to allow for the transmission of the peak signal arising from three modulators on one channel. The numbers vary for a single modulator and for more subchannels.

*This module provided courtesy of the ITS division of ADC.

RF Transmission Engineering Software

Communication Systems Design

Internet Data Management

Broadband Wireless Access

IEEE 802.16 Working Group on Broadband Wireless Access Standards

 

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Updated 30. Jul 08