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Can outdoor antenna allow reception outside clear's wimax coverage area?

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  • Can outdoor antenna allow reception outside clear's wimax coverage area?

    Would this antenna/modem combination allow me to receive Clear's Wimax signal from outside their current coverage area? If so, approximately how away from the nearest Clear Wimax transmitter can I be and still receive signal?

  • #2
    Wimax antenna not for increasing extending wimax coverage beyond cell boundary

    Can outdoor antenna allow reception outside clear's wimax coverage area?
    Would this antenna/modem combination allow me to receive Clear's Wimax signal from outside their current coverage area? If so, approximately how away from the nearest Clear Wimax transmitter can I be and still receive signal?
    No this is not the intent of this high gain antenna. We don't expect it to extend coverage outside coverage areas but rather to improve it in areas within coverage areas experiencing weak signals. This antenna is especially useful in instances where the signal is very weak inside the building but good outside. This is a tricky question actually. Since we get this quite often let me take the time to explain why in some detail.

    It's difficult to predict RF propagation properties at any frequency and for any protocol but particularly in populated areas with lots of obstructions and interference from other users. It get's even tricker for 802.15e WiMax which uses MIMO to mitigate multipath effects in a densely populated area. The reason is that each area is different and has different interference and obstructions.

    Now it could very well improve the coverage but if it did it would not be by much more than a mile or so outside the "intended" coverage area and even then the received signal strength would be too weak and unreliable to be useable. Remember also coverage zones are not exact but rather are predictions and you could experimentally find an area that is outside official coverage zone but with a signal that is not too weak to where this antenna would help. Other network parameters and Radio parameters are also important when Clearwire builds out their network such as the latency to the BTS which would increase as the distance increases.

    This antenna provides only 16dBi of directional gain. Now the Zyxel MAX206M2 Clearwire WiMax modem specifies a receiver sensitivity figure of -99dBm when using QPSK modulation
    note: i) receiver sensitivity is the minimum signal that could be reliably received by the radio at a specified Bit error rate (the lower,i.e the more negative, the better).
    ii) this receiver sensitivity figure is spec'd for QPSK which is the lowest modulation mode (lowest bit rate) so for 16QAM and 64QAM we expect a larger (worse) receiver sensitivity.

    So for example if your received signal strength is currently -102dBm then you would not be picking up the Clearwire wimax signal but by adding this antenna which has 16dBi of directional gain (standard has 5dBi directional dipole so this is a significant difference if you remember dBi is a logarithmic scale = 10xlog(gain) then even after cable losses your received signal would be above the receiver sensitivity. Same goes for transmit power (or more correctly the EIRP= Effective Isotropic Radiated Power). So even if you are currently connected but experiencing slow speed, improving your received signal could bring it above the receiver sensitivity required for a better modulation mode like 64QAM which would improve speed!

    But as discussed extensively in these forums it's hard to predict what would happen with mimo which is why we offer a 30-day return period with no restocking fees
    Last edited by thuor; 10-04-2010, 03:39 PM.
    KF7RCQ

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