To estimate pseudo code period of multipath tamed spread spectrum signal, a blind method based on power spectrum reprocessing was proposed to estimate the pseudo code period of the tamed spread spectrum signal in multipath channel. Firstly, the general single path tamed spectrum signal was extended to multipath model. Then, the primary power spectrum of the signal was calculated on the basis of the tamed spread spectrum signal model in multipath environment. Next, the obtained primary power spectrum was used as the input signal to calculate the secondary power spectrum of the signal, and the theoretical analyses showed that the peak line of the secondary power spectrum of the signal would appear in the integral multiple of the pseudo code period. Finally, the pseudo code period of the tamed spread spectrum signal could be estimated by detecting the spacing between the peak spectrum lines. In the comparison experiments with time domain correlation method, the Signal-to-Noise Ratio (SNR) of the proposed method was improved by about 1 dB and 2 dB when the correct rate of pseudo code period was 100% and the length of pseudo code sequence was 127 bits and 255 bits, and the average accumulation times of the proposed method was less under the same condition. The experimental results show that the proposed method not only has less computational complexity, but also improves the estimation correct rate.

The scale of data association increases as the map grows, which is one of the major reasons for the poor real-time performance of robot in the process of Simultaneous Localization And Mapping (SLAM). In visual SLAM system, SIFT (Scale Invariant Feature Transform) algorithm was used to extract the natural landmarks. Two improvements were introduced to improve the real-time of data association：firstly，extracted the "interest region"； secondly，took into account the physical location of current landmarks. The experimental results indicate that this kind of improvement method is reliable, and the capability of reducing computational complexity is obvious.

In order to alleviate the energy hole in wireless sensor network caused by the energy overconsumption of cluster heads, an improved algorithm was put forward. And the algorithm makes improvement on the selection and replacement of cluster heads. During the cluster heads selection, the algorithm divided the network into unequal clusters and selected the nodes with the most residual energy as cluster heads. And the cluster heads recorded the change of nodes' energy. During the cluster heads replacement, the cluster heads adopted local replacement strategy and appointed the node with the most residual energy as the next cluster head. Therefore, the algorithm modified cluster heads' energy efficiency and balanced the energy consumption among cluster heads. Finally, a simulation experiment was carried out and the experimental results show that the improved algorithm can effectively improve network performance and prolong the network life cycle.

At present, in consideration of the carrier mode, the chip design methods of ultra wideband systems mainly involve no-carrier ultra wideband, single carrier ultra wideband and multi-carrier ultra wideband. Although the three chip design methods are relatively mature, there still exist some technical difficulties, and none of them have achieved absolute advantage or extensive application. Through the researches on the related technologies and chip design examples, a comparative analysis was made on the three ultra wideband chip design methods in terms of system complexity, peak to average power ratio, overall system power consumption, frequency selective fading resistance, carrier synchronization, symbol synchronization, and spreading gain. The conclusions may provide some useful reference for the selection of ultra wideband chip design methods in different application scenarios.