Integration of different wireless networks can provide a universal ubiquitous coverage and various transmission rates for Mobile Terminals (MTs). To achieve ubiquitous computing, an MT needs to switch or handoff its connection between different or similar types of wireless networks. Our previous work used NDMD (Network Discovery based on user Motion Detection) that triggers network discovery based on an MT's motion and Received Signal Strength (RSS) to assist handoff decision. However, due to multipath fading, a wireless signal is strongly affected by environment and hence the motion detection based on RSS in NDMD may not be accurate. Thus, in this paper, we exploit a cross layer approach called packet loss aware NDMD, or PLA-NDMD, that uses TCP CWND (Congestion Window Size) as a packet loss index in couple with NDMD to cope with the problem. Experiment results show that PLA-NDMD can trigger a MT to perform handoff at appropriate timings and improve the data transmission throughput between MT and a wired station.