The uplink (Mobile to BTS link) is usually the problematic one as the mobile handset's output power is limited and its antenna is small and ineffective. This is what worries RAN engineers.
There is no point in a strong down link signal while the uplink is so low that two-way communication is not possible. Therefor the “Link Balance” issue is a crucial parameter in bi-directional communication. It is the Radio Network engineer's task to ensure the link balance is maintained.
To explain the issue of Link Balance please have a look at the following table showing how the link balance is calculated and maintained:
The above example lists all parameters affecting the link budget and how the link budgets of the Down Link and Up Link are balanced.
Please note that the BTS antenna gain (Rx antenna gain in Uplink and Tx antenna gain in Down link) is the same and does not affect the “Link Balance”.
This is to say that the higher gain VEGA improves the Rx signal in Uplink the same way it improves the signal strength in Down Link.