论文部分内容阅读
码分多址(CDMA)随时可以满足经济的数字电信业务的需求.由于CDMA可提高话音质量,增大容量,同时能提供新的业务特性,因而能为蜂窝系统、正在涌现的个人通信业务(PCS)和无线本地回路市场提供新的平台.时分多址(TDMA)是另一种在美国蜂窝系统传输方面已形成标准的数字解决方案.CDMA相对TDMA的优点本质上在于这两种技术对无线电频谱的使用方法上.TDMA采用话音信号编码器或数字化仪将语音变成数字数据,然后以30KHz的带宽在无线信道上传输这种数据.一个信道可被三个发话人共享,而每个发话人的数据则依次传输出去.在远端,每个发话者的数据被分离出来,然后再转换成原来的形式.由于TDMA系统在窄频信道上以很高速率传输数据,所以增加了信道间干扰的概率.与TDMA相比,CDMA消除了信道上由其他通话引起的串音及干扰的可能性.
Code Division Multiple Access (CDMA) is readily available to meet the needs of an economical digital telecommunications service, enabling cellular systems, emerging personal communications services (CDMA), and the like, due to the fact that CDMA improves voice quality, increases capacity and offers new business features PCS) and the wireless local loop market.Timer-time division multiple access (TDMA) is another digital solution that has been formed in the United States for cellular system transmission.The advantages of CDMA relative to TDMA are essentially the two technologies’ Spectrum on the use of TDMA voice signal encoder or digitizer to voice into digital data, and then 30KHz bandwidth on the wireless channel to transmit this data.A channel can be shared by the three callers, and each talk The data is then transmitted in turn.On the remote side, each talker’s data is separated and then converted to its original form.Because the TDMA system transmits data at a very high rate on narrowband channels, an increase of inter-channel The probability of interference Compared with TDMA, CDMA eliminates the possibility of crosstalk and interference on the channel caused by other calls.