JultikaUniversity of Oulu repository

This thesis is about testing a system’s actual performance under the IEEE 802.15.4-2011 UWB specifications, with a compliant device DW1000. It is of great interest to test the synchronization ability of different preamble lengths, which are applied in the IEEE 802.15.4-2011 UWB standard. It is also urgent to know the system’s actual performance in a multipath propagation environment, since the IEEE 802.15.4-2011 UWB standard allows an energy detection (ED) receiver to take advantage of multipath propagation. Theory predicts that a long preamble length can offer better synchronization ability at long distances, and has a longer working range. On the other hand, a long preamble length requires a longer channel occupancy time and more power consumption. Thus, a long preamble may not be the optimal choice for working at short distances. The channel model of the IEEE 802.15.4-2011 UWB standard, which is based upon the Saleh-Valenzuela (S-V) model, can be regarded as block fading. Although multipath propagation can improve the system’s performance by increasing the SNR, the effects of block fading on the system must be taken into account as well. It is pointed out in various papers that the S-V model is precise in predicting a none-line-of-sight (NLOS) environment, while it is not precise in predicting a line-of-sight (LOS) environment. The results of the first part of the measurements show that longer preambles have longer working ranges. However, the longer preambles’ performance, in the term of the packet reception ratio, is not necessarily better than that of the shorter preambles. The results of the second part of the measurements show that the system can take advantage of multipath propagation. On the other hand, the system’s performance might become instable, due to block fading. The receiver and the transmitter will have difficulty in synchronization, if the channel impulse response changes too much within the unsynchronized time period. A longer preamble length tends to offer a longer stable working range. In addition, the path loss of the channel will suddenly increase and then decrease. This phenomenon of a sudden change in the path loss at a certain distance is quite similar to that of a narrowband system.