WCDMA(W ideband Code D ivision Mu ltip le Access)系统的一个重大挑战,就是在保证服务质量的前提下,承载各种不同类型的业务。为此,在对WCDMA网络的QoS(Quality of Service)和QoE(Quality of End-user Experience)管理、网络监测和优化等问题进行研究的基础上,分析了几种网络配置以及实时业务向不同QoS等级映射的问题,给出了优先选择方法区分服务模型。结果表明,该模型系统能以最符合成本效益的方法承受QoS实时服务,灵活地处理区分服务业务,QoS测试结果验证了预期优先选择方法的优越性。运用优先选择方法后,网络的频谱利用率达到32%;区分服务模型使网络的资源使用能力提高了23%。
We report the adaptive compensation experiment of polarization mode dispersion (PMD) for 10-Gb/s non return-to-zero (NRZ) and return-to-zero (RZ) optical communication systems using a two-stage PMD compensator and the monitoring technique based on degree of polarization (DOP) feedback-signals. The DOP monitor has its advantages of bit-rate independent and modulation format independent. The two-stage compensator has the capacity of compensation for the first- and second-order PMD. The compensated differential group delay (DGD) is up to 80 ps, and compensated principal state of polarization rotation rate is 20 ps. The time used for compensation is less than 1 second.
An experiment of two-stage adaptive compensation for polarization mode dispersion (PMD) iu a 40-Gb/s optical time-division multiplexed communication system is reported. The PMD monitoring technique based on degree of polarization was adopted. The particle swarm optimization (PSO) algorithm was introduced in adaptive PMD compensation. The comparison was made to estimate the effectiveness between PSO algorithms with global neighborhood structure (GPSO) and with local neighborhood structure (LPSO). The LPSO algorithm is shown to be more effective to search global optimum for PMD compensation than GPSO algorithm. The two-stage PMD compensator is shown to be effective for both first- and second-order PMD, and he compensator is shown to be bit rate independent. The optimum searching time is within one huudred milliseconds.
