| 2. | Future mobile communications have to support the transmission of high rate data and multimedia applications in the radio spectrum , which is already extremely scarce . the basic idea of adaptive coded modulation is to maintain a constant throughput by varying the transmitted power level , symbol transmission rate , constellation size , coding rate or any combination of these parameters . thus , without sacrificing bit - error rate ( ber ) , these schemes provide high average spectral efficiency by transmitting at high speeds under favorable channel conditions , and reducing throughput as the channel degrades
自适应编码调制( adaptivecodedmodulation , acm )的基本思想是在不牺牲系统传输性能(比如ber )为代价的前提下,通过单独改变发送功率、波特率、编码方案、码率、调制方式,或者是综合改变前面所述的各种参数,在有利的信道条件下,获得较大的吞吐量,当信道质量下将时,相应地降低传输速率,最终达到提高平均频谱效率的目的。 |
