in the same way it is by a conventional dial-up modem.=in the same way (that) it is performed by a conventional dial-up modem.
it指代the encoding and decoding;by的意思就是“被”。
省掉performed不但不影响理解反而使句子更加简洁。
或直接把in the same way看成一个连词,或认为在它的后面省掉了定语从句的关系副词that。
The encoding and decoding is performed at the exchange and at the user end respectively, in the same way it is by a conventional dial-up modem .
我个人的看法:从全句意思来看,第二句中it 指代整个前一句话,编码技术和解码技术分别在交换机和用户端,这种方案同样用于拨号调制解调器。因此介词by 可翻译成“采用”。
问题是:词典里没有合适的含义,一大堆释义中不知用哪个,而书中给出的is和by连用的例句中by都是在……旁边的意思。请问老师,哪个含义符合我这句话呢?