I installed and configured a wireless network using Linksys router 802.1g so about 20 users accessing the network and we are agressively increasing in number of users so I want to know is this router will be adaptable for that increasing no. of users or I need to change to more advance access point like Cisco aironet series
Personally, i would switch over to the Cisco product.. However this is personal preference due to my comfort level with the Aironet APs and their reliability.
The most critical information in this situation is what you intend to do with this wireless network. With 60 clients, with out knowing your environment or resource requirements, i would state that you require at least 3 APs. However different applications have different bandwidth requirements.
If this is a small confined space you can utilize three seperate APs using channels 1,6, and 11. That is if your in North America.
If it expands even further yet maintain a small space you COULD expand into the 5ghz range.
As Robert already mentioned above, with 60+ users you will need to add additional APs to keep the performance satisfactory.
The bottleneck is not the hardware in the AP, rather, it is the arbitration methods of CSMA/CA employed by 802.11 (interframe spacing, beacons, defferals, backoff timers, ACKs etc). Its a shared medium, like a hub, except the rules are stricter than plain ethernet, such as the fact that every data frame must be acknowledged by the AP. And so on...
By adding additional APs the idea is to reduce the number of users per BSS (basic service set) and thus reducing the overall congestion which will improve performance.