Sharing Limesdr board with multiple users on different PCs

Can it be possible to share Limesdr board among users on different PCs who want to transmit or receive signals with different modulation schemes???

I’ve not heard of anything that does what you want.

But maybe you could create a GnuRadio Companion flowgraph, something along the lines of the following (take the details with a grain of salt):
Server: LimeSDR Source block-> “Polyphase Channelizer” block ->“UDP Sink” blocks
Client(s): “UDP Source” block -> rest of normal flowgraph
And the port numbers of the all the UDP blocks would allocate individual frequency channels to individual remote clients.

Server:: “UDP Source” blocks->“Frequency Xlating FIR filter” blocks ->“Polyphase Synthesizer” -> LimeSDR Sink block
Client(s): flowgraph->“UDP Sink”
And the port numbers of the all the UDP blocks would distribute the clients across a number of allocated frequency slots. And the Xlating FIR would adjust the offset within the bandwidth.

(ref: - for virtuzal interfaces and file sources and sinks, but the broad brush strokes would be similar)
So you would have a range UDP port numbers for RX channels and a different range for UDP port numbers for TX channels.

But that would assume that you are using UDP to transfer the IQ streams, and that would limit your choice of tools to probably only Gnuradio in reality.

With the above there would be many sources of delay and jitter and how many channels you could use at once would be limited by the processing power on the server and the network bandwidth. e.g. If the server had full duplex gigabit (~112MiB/sec) and say 20 clients, assuming I and Q are 4-byte floats, that would on paper be ~730kHz to/from each client (~14.5MHz on the server), but you would never get that so assume 10% (maybe 20% of that) as more realistic starting point so 50kHz per client and 1MHz bandwidth on the server (or ~8MiB/sec continuous streaming network bandwidth).

Another option may be using soapyremote, but I would guess that “use the device on multiple hosts” may mean by one host at a time, not all simultaneously. But I’ve never used that feature myself, so I would not know.