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This study presents a chip rate and pseudo-noise (PN) sequence estimation algorithm of direct sequence spread spectrum signals. The received signal samples are divided into temporal segments, from which the correlation matrix is computed and decomposed. Then the principal eigenvector of this matrix is de-noised. The chip rate and the PN sequence are estimated from the de-noised principal eigenvector. The computational complexity is also evaluated. Theory analysis and computer simulation results show that, compared with other algorithms, the performance of proposed algorithm is significantly improved at the approximate computational complexity. In addition, an improved version with low computational complexity is available. Simulation results also verify the effectiveness and superior performance of improved algorithm in low signal-to-noise ratio.

Introduction: Periprosthetic bone mineral density (BMD) loss following total hip arthroplasty (THA) may threaten the survival of the implant, especially in patients with osteoporosis. Zoledronic acid (ZA) is the representative of the third generation of bisphosphonates, which were effective in reducing bone loss in conditions associated with accelerated bone turnover. The aim of this study was to evaluate the efficacy and safety of ZA in patients with osteoporosis after THA.Methods: Randomized controlled trials (RCTs) associated with ZA and THA were searched from the MEDLINE, PubMed, EMBASE, Wanfang database, and the Web of Science (August 2021). Other methods, such as hand search and email request were also tried. The methodological quality was assessed by the Risk of Bias (RoB) 2.0. Relevant data were abstracted from the included RCTs and authors were contacted when necessary.Results: In this study, six RCTs involving a total of 307 patients were finally included and analyzed. The pooled data demonstrated that significantly less periprosthetic BMD loss in Gruen zone seven had occurred in the ZA-treated patients than in the control patients at 3 months (mean difference [MD] = 4.03%; 95% CI: 0.29–7.76%; P = 0.03), 6 months (MD = 7.04%; 95% CI: 2.12–11.96%; P = 0.005), and 12 months (MD = 7.12%; 95% CI: 0.33–13.92%; P = 0.04). The Harris Hip Score (HHS) was also significantly increased in ZA group at 6 and 12 months after operation (P = 0.03 and P = 0.02, respectively). Influenza-like symptom was found related to the usage of ZA [relative risk (RR) = 7.03, P < 0.0001].Conclusion: A meta-analysis of six RCTs suggested that ZA was beneficial in maintaining the periprosthetic BMD in patients with osteoporosis at 6 and 12 months after THA. In addition, the HHS was significantly improved in patients treated with ZA. However, the short length of follow-up of the available studies resulted in the lack of analyses regarding the survival of implants including the rate of aseptic loosing, periprosthetic fracture, and revision. It still needs to be determined in research with longer follow-up period.Clinical Trial Registration:Researchregistry.com, identifier: reviewregistry1087.

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