## 4 Performance and Simulation Results
### The Modified BA Protocol, MBA
#### 4.3.2 The Impact of Interference  
In this subsection, a simulation of 300 tags existed in the entire zone of Figure 3 moving at any velocity for GBT, TBT, GQT1, and GQT2 protocols was conducted with varying interference probabilities (_pi_) from 0 to 0.5 under the following conditions: velocities of 1 m/frame (blocking velocity) and 3.5 m/frame (non-blocking velocity) for the MBA. All of the simulated protocols (except the modified protocol, MBA) do not distinguish between collision and interference signals, because the blocking technique is not employed. Thus, the efficiency of identification process is reduced, as the probability of interference is increased due to consuming more cycles. The exception to this lack is in the uniform distributions of GQT1 and GQT2 shown in Figure 7e, since success or interference cycles never happen except for in the full-length of ID reader prefix, in which the interference response can be distinguished as success cycle. Consequently, GBT and TBT consumes more collision, idle, and total cycles, as shown in Figure 7b, d, and e, as interference probability increases due to the branching of the tree of identification process through one tag response. On the other hand, for GQT1 and GQT2 with uniform distributions, the success response (one tag matches reader prefix) never happens until full ID prefix is prepared by the reader. In this case, even the collision response is detected by the reader (due to interference signals). The reader can deduce that there is only one tag responds to its query (there is only one tag ID matches reader full prefix), and thus the response is considered as success without consuming more of collision and idle cycles due to the tree branching, see Figure 7b  
Figure 6: The impact of capture effect: (**a**) success cycles, (**b**) collision cycles, (**c**) idle cycles, and (**d**) total cycles. and d. In contrary, for GQT1 and GQT2 with non-uniform distribution, the collision cycles increase as interference probability rises due to the tree branching through collision response, when only one tag responds with signal corrupted (due to interference signals). Besides, the idle cycles for GQT1 decrease as interference probability rises. Because the success prefixes are nearly equal, there are full prefixes for large number of tags. Therefore, the collision response due to interference signals of \(ID_{full\ prefix}-1 bit\) reader's query length branches the tree to \([ID_{full\ prefix}-1 bit\) 0] and \([ID_{full\ prefix}-1 bit\) 1]; one of these two queries will be success cycle without branching (full prefix length), and the other query will be idle cycle. If the response is successful due to \(ID_{full\ prefix}-1 bit\) length, the reader will consume two idle cycles instead of one through tree branching. In adverse, GQT2 consumes more idle cycles as interference probability rises, since the reader repeats its prefix (consumes only one idle cycle) instead of tree branching in GQT1 for successful response. As a result, the total cycles are increased for non-uniform distribution of GQT1 and GQT2, and remain constant for uniform distribution, as illustrated in Figure 7e. Finally, for the modified protocol, MBA, the collision, idle, and total cycles are increased as interference probability rises but without tree branching for the period of staying tags, because MBA separates the collision and interference responses for the mentioned period while BA does not. Thus, MBA outperforms the other protocols, including BA and the non-uniform distributions for GQT1 and GQT2 (practical case), in consuming less total number of cycles for pi from 0 to 0.5. For pi from 0 to 0.25 when comparing with GQT1 and GQT2 with uniform distributions (unpractical case), see Figure 7e. For instance (at 1 m/frame velocity), at pi equals 0.5 and 105 of success cycles (identified tags), BA protocol consumes 120, 175, and 400, collision, idle, and total cycles, respectively, whereas MBA protocol consumes only 51, 74, 80, and 310, collision, interference, idle, and total cycles, respectively.