Many factors affect range for any broadband wireless product.  Some factors include the terrain and density/height of tree cover.  Hills and valleys can block or partially reflect signals.  Bodies of water such as rivers and lakes are highly reflective of RF transmissions.  Fortunately OFDM can often turn this to an advantage---but not always.  The RF shadow of large buildings can create dead spots directly behind them, particularly if license-free spectrums are being used (with their attendant lower power allotments).  How busy the RF environment of a city or town is can greatly degrade signals---meaning that properly designed and well thought out networks are always desired.  The physics of radio transmission dictate that the greater the range between the base station and customer radio, the lower the amount of bandwidth that can be delivered, even in an extremely well-designed network.  The climate can affect radio performance---despite this there are ubiquitous wireless networks deployed today with great success in frozen Alaskan oil fields as well as lush South American and Asian climates.  And increasingly WiMAX radio antenna technology coupled with the inherent advantages of OFDM/OFDMA based radios can be a major factor in range and bandwidth capability.  The new multiple input multiple output (MIMO) and adaptive antenna systems (AAS) based antenna systems promise to maintain and even link connection and link budgets with much higher bandwidth than older technology. 

No two cities are exactly alike in terms of the challenges and opportunities presented.  In many respects, broadband wireless remains very much an art form.  However, this is also true for the cellular carriers most of us use daily.  It can be done quite well.  Mobile broadband wireless will be more difficult.  Achieving high quality of service (QOS) will be easier with fixed broadband wireless.  Despite all of these challenges, current broadband wireless is very effectively serving customers even in the most challenging environments.