Improved algorithm for UPnP discovery in smart space

The current UPnP service discovery algorithm can cause severe drops with response message rate when applied in pervasive computing environments with large scale of services. The deficiency lies in the instantaneous transmission of all response messages and the independent random selection of the transmission delay so that the response messages collide and congest. To reduce the congestion, a refined algorithm is developed which is based on unchanged the root device's discovery protocol, control point using multiple adaptive maximum query time (MX), to ensure that devices in the environment can be discovered. The simulation verifies that the refined algorithm gives better performance in the response message's drop ratio.