Each end with nothing to say just periodically sends an empty data packet with its current sequence, acknowledgement and window Numbers.

每个终端只需间歇地发送一个包含当前序列的空的数据包，确认信息和滑动窗口号就可以了。

youdao

Satellite, surprisingly, came out as having the best throughput although before you rush out to get satellite service remember that the roundtrip latency (the time it takes a data packet to go from your PC to its destination and for an acknowledgement to come back) over a satellite connection is often in the range of 900 milliseconds to 1, 400 milliseconds.

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