Realistic beamforming design using SRS-based channel estimate for ns-3 5G-LENA module

Abstract

Beamforming (BF) is a key procedure to overcome propagation limits in millimeter-wave bands but also to extend network coverage in sub 6 GHz bands, as considered in recent 3GPP and IEEE communication standards. Up to date, ns-3 included various ideal BF methods, in which an ideal channel state acquisition is assumed and no BF overhead is considered. However, ns-3 lacks the implementation of realistic BF methods, in which the overhead needed to perform BF-related procedures and the errors due to a non-ideal channel state acquisition are taken into account. A way to perform realistic BF is to rely on Sounding Reference Signals (SRS) for channel estimation and then determine the best BF vectors based on the channel estimate. In this paper, we first present an abstraction model to perform BF using SRS-based channel estimation, and then we provide the implementation details of 5G New Radio (NR)-compliant SRSs and new realistic BF methods using SRS-based channel estimate, as included in the ns-3 5G-LENA simulator. Simulations are provided to compare realistic BF and ideal BF methods, for different propagation scenario conditions and SRS transmitted powers. CCS CONCEPTS• Networks → Network simulations; Mobile networks.

ns-3 and 5G-LENA Extensions to Support Dual-Polarized MIMO

“…Later on, we introduced the representation for a quasi-omnidirectional beamforming, and multiple combinations with the previous methods (e.g., the gNB using beam search method and the UE using quasi-omni reception). Recently, we went a step over the ideal beamforming methods, and implemented realistic beamforming methods using SRS-based channel estimates [5]. That is, we used SRS (transmitted in specific time/frequency resources) to estimate the channel matrix, and then determine the beamforming vectors at the gNB based on the SRSbased channel estimate.…”

“…However, all the methods available in ns-3 NR modules (mmwave and nr) [5,11,12] up to date, were focusing on MIMO beamforming and they were missing the support of MIMO spatial multiplexing. With the contribution of this paper, we start to fill this gap.…”

“…The ns-3 mmwave module for 5G NR in mmWave bands [11], as well as the ns-3 nr (5G-LENA) module for 5G NR in sub 6 and mmWave bands [12] support various ideal beamforming methods. Recently, we developed realistic beamforming methods [5], for which real resources are employed to perform beam management, considering a non-ideal channel estimation. However, both modules have been lacking up to now MIMO spatial multiplexing feature.…”

ns-3 and 5G-LENA Extensions to Support Dual-Polarized MIMO

“…Later on, we introduced the representation for a quasi-omnidirectional beamforming, and multiple combinations with the previous methods (e.g., the gNB using beam search method and the UE using quasi-omni reception). Recently, we went a step over the ideal beamforming methods, and implemented realistic beamforming methods using SRS-based channel estimates [8]. That is, we used SRS (transmitted in specific time/frequency resources) to estimate the channel matrix, and then determine the beamforming vectors at the gNB based on the SRS-based channel estimate.…”

“…The ns-3 mmwave module for 5G NR in mmWave bands [16], as well as the ns-3 nr (5G-LENA) module for 5G NR in sub 6 and mmWave bands [17] support various ideal beamforming methods. Recently, we developed realistic beamforming methods [8], for which real resources are employed to perform beam management, considering a non-ideal channel estimation. On the other hand, the mmwave module was recently extended to support multi-user MIMO (MU-MIMO), i.e., to send different streams towards different users [12].…”