Opportunistic scheduling for heterogeneous services in downlink OFDMA system

We consider opportunistic scheduling in a downlink OFDMA system to support heterogeneous services. Given the user's queue state information (QSI) and channel state information (CSI), the proposed sum waiting time based scheduling (SWBS) algorithm can guarantee QoS requirements for both real-time (RT) and non-real-time (NRT) service. The benefit is attained from scheduling heterogeneous services based on sum packet waiting time to fulfill the QoS requirements and exploiting multiuser diversity to achieve effective resource utilization. Simulation results illustrate that the max packet loss ratio and packet delay for real-time service and the throughput for non-real-time service are improved by the proposed algorithm. © 2009 IEEE

Throughput optimization for orthogonal random beamforming in multi-user MIMO-TDMA downlink

We address the problem of throughput optimization in MIMO-TDMA downlink using orthogonal random beamforming (ORBF), which has been intensively studied recently because of its ability to exploit multi-user diversity and spatial multiplexing gains with partial channel state information (CSI). We formulate an optimization problem which aims at maximizing the total throughput under the constraint of individual long term throughput guarantee for each user. Although this problem is generally non-convex, we find that the optimal solution can be found with high probability by combine convex optimization algorithms with a well designed initial algorithm. By comparing the solution of the proposed method with the optimal value of the dual problem, we showed that the optimal throughput is usually achieved by the proposed method

A greedy-based resource allocation algorithm for multicast and unicast services in OFDM system

We propose a resource allocation algorithm for OFDM system to provide QoS guarantee for unicast and multicast service concurrently. The optimization objective is to maximize the sum rate of the unicast service under the constraint of both the total power and the minimal rate provision of the multicast service, which can be solved by traditional two-step approach. To decrease the complexity, a greedy-based algorithm is proposed. According to the theoretical analysis and the simulation results, the performance of the proposed algorithm is close to the two-step approach meanwhile the complexity is effectively decreased. In conclusion, the proposed algorithm can balance the performance and the complexity well and so is suitable to be applied to practical scenario.Computer Science, Hardware & ArchitectureEngineering, Electrical & ElectronicTelecommunicationsEICPCI-S(ISTP)

Three-year outcomes of individualized ranibizumab treatment in patients with diabetic macular edema: the RESTORE extension study.

OBJECTIVE To evaluate long-term efficacy and safety profiles during 3 years of individualized ranibizumab treatment in patients with visual impairment due to diabetic macular edema (DME). DESIGN Phase IIIb, multicenter, 12-month, randomized core study and 24-month open-label extension study. PARTICIPANTS Of the 303 patients who completed the randomized RESTORE 12-month core study, 240 entered the extension study. METHODS In the extension study, patients were eligible to receive individualized ranibizumab treatment as of month 12 guided by best-corrected visual acuity (BCVA) and disease progression criteria at the investigators' discretion. Concomitant laser treatment was allowed according to the Early Treatment Diabetic Retinopathy Study guidelines. Based on the treatments received in the core study, the extension study groups were referred to as prior ranibizumab, prior ranibizumab + laser, and laser. MAIN OUTCOME MEASURES Change in BCVA and incidence of ocular and nonocular adverse events (AEs) over 3 years. RESULTS Overall, 208 patients (86.7%) completed the extension study. In patients treated with ranibizumab during the core study, consecutive individualized ranibizumab treatment during the extension study led to an overall maintenance of BCVA and central retinal subfield thickness (CRST) observed at month 12 over the 2-year extension study (+8.0 letters, -142.1 μm [prior ranibizumab] and +6.7 letters, -145.9 μm [prior ranibizumab + laser] from baseline at month 36) with a median of 6.0 injections (mean, 6.8 injections; prior ranibizumab) and 4.0 (mean, 6.0 injections; prior ranibizumab + laser). In the prior laser group, a progressive BCVA improvement (+6.0 letters) and CRST reduction (-142.7 μm) at month 36 were observed after allowing ranibizumab during the extension study, with a median of 4.0 injections (mean, 6.5 injections) from months 12 to 35. Patients in all 3 treatment groups received a mean of <3 injections in the final year. No cases of endophthalmitis, retinal tear, or retinal detachment were reported. The most frequently reported ocular and nonocular adverse effects over 3 years were cataract (16.3%) and nasopharyngitis (23.3%). Eight deaths were reported during the extension study, but none were suspected to be related to the study drug/procedure. CONCLUSIONS Ranibizumab was effective in improving and maintaining BCVA and CRST outcomes with a progressively declining number of injections over 3 years of individualized dosing. Ranibizumab was generally well tolerated with no new safety concerns over 3 years