# On the Performance of Partial LIS for 6G Systems
## 3 Simulation Results and Analysis
The different graphics representing the performances include matched filter bound (MFB) curves. These represent a lower bound in performance, corresponding with a scenario without intersymbol interference. In other words, this corresponds with the performance when a single symbol is transmitted and in which the degradation is due only to fading. Figure 4 shows the performance results with the 4 \(\times\) 400 LIS system, with 2 users, without LDPC codes, with and without the partial LIS. The 4 \(\times\) 400 LIS system means that 4 panels of 400 antennas each are utilized (20 antennas on each side of the panel), making a total of 1600 antennas as part of the LIS. The number of users is 2, which means that there is one reference user and one interfering user. As can be seen, for the full LIS (i.e., with the use of 4 panels, each with 400 antennas), the ZF receiver has a performance slightly better than the MRC. Nevertheless, the MRC presents the advantage that the receiver is much simpler, as it does not require the channel inversion for each frequency component of the channel. When only a subset of the whole LIS is utilized (partial LIS), using only 225 antennas out of the total 1600, the performance achieved is much worse than that of the whole LIS, for both receiver types. Nevertheless, when the partial LIS comprises 361 antennas out of a total of 1600, one can see that the performance is slightly better than that of the full LIS. This occurs because the number of antennas utilized by the partial LIS (361) is sufficiently high, compared with the total (1600), enabling the exploitation of diversity. In addition, the slight gain of performance obtained with this configuration compared with the full LIS also results from the fact that a partial LIS allows interference mitigation. Similarly, observing the performance results achieved with \"partial LIS--one panel\", the performance obtained is even better than that obtained with 361 antennas. Note that one panel corresponds with the use of the panel that is closer to each user, comprising 400 antennas (i.e., more than the previously considered 361 antennas), and, therefore, with the increasing gain obtained with the beam, while the ability to mitigate interference is kept. It is worth noting that the ZF receiver achieves a performance slightly better than that of the MRC receiver, in all scenarios, though at the cost of a higher complexity (processing at the receiver side). Figure 5 shows the performance results with the 4 \(\times\) 225 LIS system, with 2 users, without LDPC codes, and with and without the partial LIS. The 4 \(\times\) 225 LIS system is one in which 4 panels of 225 antennas each are utilized (15 antennas on each side of the panel), making a total of 900 antennas as part of the LIS. Like the previous graphic, the number of users is 2, which means that there is one reference user and one interfering user. The \"full LIS\" corresponds with the use of the total of 900 antennas, while the \"partial LIS--one panel\" corresponds with the use of the panel (with 225 antennas) that is closer to each user, mitigating the interference. As can be seen, like the results of the previous figure, results obtained with \"partial LIS--one panel\" indicate improvement over the performance obtained with \"full LIS\", for the different receiver types. This happens because the number of antennas per panel is still sufficiently high (225 antennas), allowing a good gain in terms of diversity, while mitigating the interference over the interfering user due to the use of a single panel, instead of the whole LIS. In terms of receiver types, one can see that ZF and MMSE receivers achieve the same performance, leading to the best results. This is followed by the low complexity MRC receiver, whose performance is always between those obtained with ZF/MMSE and EGC receiver.