Optimizing, testing and comparing performance of massive MIMO base station algorithms and RF hardware settings require a RF channel emulator that is capable of emulating in real-time the massive MxK RF channels, where M≥64 is the number of RF paths in the base station and K≥8 is the number of spatially multiplexed UE data streams in the same resource block.
The RMB-101A (download datasheet) is a high-performance Software Define Radio (SDR) 8Tx/8Rx Multi-Channel Transceiver Module for a Remote Radio Unit for a Base Band Unit (BBU) located from a few meters to over 10 km away from the radio in a C-RAN type network or for distributed massive MIMO.
Our Massive C-RAN DSP Engine is the largest C-RAN DSP Engine in the market. It has 64 10Gbps CPRI, capable of supporting the DSP processing of the IQ streams of up to 512 Tx/Rx radios, either for Distributed Massive MIMO or resource pooling at the lower PHY level in a C-RAN network. It is compliant with LTE and CPRI standards.
The AVALO-RU64A is a high-performance Remote Radio Unit (RRU or RU) for a Massive MIMO BTS system. Multiple RRUs can be linked back to a Cloud-RAN (C-RAN) central processing node for distributed massive MIMO.
The RDB-B41TA is a high-performance multi-channel MIMO RF Frontend (FE) Module. It includes 8 independent TX Power Amplifier (PA) channels, and 8 independent RX Low Noise Amplifier (LNA) channels. The working band is TDD band 41 (2496 – 2690 MHz). In the TX chain, the gain is ~30 dB, and the output power for CW is +29 dBm, for LTE is about ~+18 dBm with ACLR > 47 dB. Both input and output return loss are ~12 dB. In the RX chain, the gain is ~24 dB, max CW input level lower than -3 dBm, for LTE input signal, the max input level is lower than -15 dBm. The RX Noise Figure (NF) is about 4 dB and the both input and output return loss about 15 dB.
Massive MIMO takes advantage of the reciprocity of the over-the-air (OTA) channel in TDD to reduce the overhead in channel estimation. It estimates the downlink channel based on the uplink channel obtained from SRS in uplink. For this to work, the Tx and Rx chains in the base station RU must be calibrated so that they are reciprocal. This module is similar in function to our 8×8 MIMO SDR except this module has built-in circuit to perform the reciprocal calibration of the 8Tx and 8Rx chains. More importantly, the built-in calibration circuits can be chained for reciprocal calibration of a larger RU, e.g., a RU with 64Tx and 64Rx chains.