Hello Pavan,
Are you trying to create a shared timebase between the two USRPs without having a shared 1PPS or GPS reference? You are still not using enough detail for us to understand fully.
In Figure 5 both USRPs are connected with a MIMO cable and so have both shared frequency and time bases. What is your weight block doing to the sample stream? Is it a time delay block? I don't know what gnuradio would do if you specified 10*sample_rate as the delay there as that's likely to be a very large number of samples.
If you have both USRPs connected with a time synchronization (shared 1PPS, GPSDO, or MIMO cable) and have your flowgraph configured correctly, then you can just use timed commands to the USRP_alpha to start transmitting at time X and USRP_beta to start receiving at time X and you will see your signal. You can then move to using burst mode using tags to define the number of samples to send/receive along with timed commands to send/receive bursts of samples. This works because the clocks in both USRPs will be aligned to each other.
If you do *NOT* have a shared time source for each radio, for instance they are far apart and do not have GPS references, then you need to do some sort of protocol level alignment to create a shared understanding of time between them. A frequently used method is for USRP_alpha to transmit a beacon with a known period (say once every 10 seconds). All other USRPs then receive for longer than 10 seconds to be guaranteed to receive the beacon (assuming they're within range of the transmission). When the receiving USRPs detect the incoming beacon they align their local time to the master (Beacon transmitting) USRP.
I hope this helps and is applicable to your need. If you have more questions please try drawing your desired system and maybe include a timeline of events that you expect the radios to do. Attaching your existing flowgraphs, either as photos using GRC's screen capture feature (file>screen capture) or the actual GRC file, also helps us understand what exactly you are working with.
Derek