The performance of LTE-Advanced systems which is based on orthogonal frequency division multiplexing (OFDM) is significantly restricted by inter-cell interference(ICI). Advancing the performance of cell edge users who experienced strong ICI is still a crucial issue. Therefore Coordinated Multi-Point transmission/reception (CoMP) is brought forward to solve this problem. In this paper, it focused on the downlink coordinated beamforming of CoMP with limited feedback, and proposed a method based on signal-to-leakage-and-noise ratio (SLNR) and Signal Noise Ratio (SNR) criteria to choose the optimal beamforming vector from codebook, which made the user to possess higher throughput and produce less interference to other users located in coordinated cells. Simulation results indicate that the proposed method gives an effective control of ICI and improves cell edge user throughput.

Device-to-device (D2D) multicast communication is a useful way to improve the communication efficiency of user equipments which are located close to each other. In this paper, the frequency resource sharing problem of D2D multicast communications underlying single frequency network (SFN) system is investigated. Firstly, to avoid the interference between D2D and cellular communication and without consuming more frequency resources, we assume that D2D multicast groups do not share frequency with cellular user equipments (CUEs) in the same SFN, but reuse frequency with CUEs in other SFNs. Then, according to a pre-setting threshold of signal to interference ratio (SIR) of D2D communication, a reuse safe distance is confirmed. Finally, a round-robin resource allocation algorithm is proposed. Simulation results show that the proposed resource sharing algorithm can significantly reduce the outage probability of both D2D and cellular communication and enhance the throughput of system.

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IntroductionDiabetes mellitus (DM) has been proved to contribute to multiple comorbidities that are risk factors for abdominal aortic aneurysm (AAA). Remarkably, evidences from epidemiologic studies have demonstrated a negative association between the two disease states. On the other hand, hyperglycemic state was linked to post-operative morbidities following AAA repair. This review aims to provide a thorough picture on the double-edged nature of DM and major hypoglycemic medications on prevalence, growth rate and rupture of AAA, as well as DM-associated prognosis post AAA repair.MethodsWe performed a comprehensive search in electronic databases to look for literatures demonstrating the association between DM and AAA. The primary focus of the literature search was on the impact of DM on the morbidity, enlargement and rupture rate, as well as post-operative complications of AAA. The role of antidiabetic medications was also explored.ResultsRetrospective epidemiological studies and large database researches associated the presence of DM with decreased prevalence, slower expansion and limited rupture rate of AAA. Major hypoglycemic drugs exert similar protective effect as DM against AAA by targeting pathological hallmarks involved in AAA formation and progression, which were demonstrated predominantly by animal studies. Nevertheless, presence of DM or postoperative hyperglycemia was linked to poorer short-term and long-term prognosis, primarily due to greater risk of infection, longer duration of hospital stays and death.ConclusionWhile DM is a positive factor in the formation and progression of AAA, it is also associated with higher risk of negative outcomes following AAA repair. Concomitant use of antidiabetic medications may contribute to the protective mechanism of DM in AAA, but further studies are still warranted to explore their role following AAA repair.

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