In low-power low-rate wireless networks, IEEE 802.15.4 is a standard protocol for communication. Devices in such networks are usually battery-operated so radio-transceiver component in such networks are typically of low range but most power consuming. Proper antenna orientation, distance between nodes and channel selection are among the ways to achieve reliability in these networks. But these arrangements can affect the link qualities and achieved communication performance in IoT applications. In this work, we have evaluated the performance of IEEE 802.15.4 links using Zolertia Z1 motes experimentally through indoor/outdoor real scenarios. We have found that RSSI decreases with distance and is effected by the height of the motes. The antenna polarization drastically affects the RSSI whereas LQI and packet delivery ratio is not much affected. We also found that the non-interfering channels 26 and channel 15 are effected by Wi-Fi in the same way. Moreover the contiki MAC performs better than XMAC protocol.