Hi,
In LTE Rel 8 Tm modes are range form (1 - 7), In this important TM modes are (1 - 5).
TM mode 1 :
This TM mode is used when Single antenna is present in sender or receiver. This mode is very basc and it wont achieve LTE actual result.
TM mode 2 :
This mode is transmit diversity, When an user not having good channel quality over antenna or user didn't support MIMO(refer next modes) then ENb will use TM 2. This will have 2 antenna, and single TB will be replicated in both the antenna so that TB will be recovered in the Rx side effectively. But through put will be normal.
TM mode 3 :
This is open loop MIMO(multi input multi output) , which transmitter wont bother about receiver feed back , If receiver is able to differentiate both antenna signal means Tx will transmit different TB in different antenna. Through put will be higher in case of stable user in TM3.
TM 4 :
This is closed loop MIMO, In which Tx will adjust its transmission based on the Rx feed back based on PMI. This type of TM mode will be used to achieve MAX throughput in LTE.
TM 5 :
This is Multi user MIMO, In which each user will be mapped to particular single antenna so that ENb can achieve MAX no of UE with avg throughput in LTE.
