We propose Multi-Antenna (MA) Towards Inband Shift Keying (TISK): a new multi-carrier radio concept to cope with critical link budgets. In contrast to common proposals that rely on analog beamforming at both transmitter and receiver, MA-TISK does not require beam alignment. The transmitted signals have all constant envelope in continuous time, which allows for efficient, low-cost power amplification and up-conversion. The concept is compatible with any linear PSK-modulation as well as pulse position modulation. Each sub-carrier is sent over a separate antenna that is equipped with a voltage-controlled oscillator. The phases of these oscillators are controlled by digital baseband. Temporal signal combining makes up for the lack of beamforming gain at the transmitter. A common message may be broadcast to many receivers, simultaneously. Demodulation can be efficiently implemented by means of fast Fourier transform. MA-TISK does not suffer from spectral re-growth issues plaguing other constant envelope modulations like GMSK. Almost rectangular signal spectra similar to those for linear modulation with root-raised-cosine pulse shaping are possible. For the 100 MHz-wide spectral mask of 5G downlink, QPSK-modulation allows for 160 MBit/s with 5.74 MHz subcarrier spacing when using 16 transmit antennas. The wide carrier spacing makes the signals insensitive to Doppler effects. There is no loss in link budget gain compared to spatial beamforming at the transmitter.

翻译：我们提出多天线-带内移位键控（MA-TISK）：一种应对关键链路预算的新型多载波无线电概念。与依赖发射端和接收端均采用模拟波束成形的常见方案不同，MA-TISK无需波束对准。所有发射信号在连续时间内具有恒定包络特性，从而支持高效低成本功率放大与上变频。该概念兼容任意线性PSK调制及脉冲位置调制。每个子载波通过配备压控振荡器的独立天线发射，这些振荡器的相位由数字基带控制。时域信号合路补偿了发射端缺乏波束成形增益的不足。公共消息可同时广播至多个接收器，解调可通过快速傅里叶变换高效实现。MA-TISK不存在困扰其他恒定包络调制（如GMSK）的频谱再生问题，可实现近乎矩形频谱（类似于采用根升余弦脉冲成形的线性调制）。针对5G下行链路100 MHz频谱掩模，当使用16根发射天线且子载波间隔为5.74 MHz时，QPSK调制可支持160 MBit/s速率。宽子载波间隔使信号对多普勒效应不敏感。与发射端空间波束成形相比，链路预算增益无损失。