Dear LeHung,
3. It will be attached according to max SINR.
5. exactly
Please be aware that the system level-simulator is downlink-only. You could specify the properties of an eNodeB such that it imitates a user. If you want to have a macro-network with underlying UE-to-UE connections, you can imitate this by adding small cells (your “transmitting users”), and specify the small cell parameters according to the desired UE specs.
Best regards,
Martin.