Abstract
Link adaptation in coherent wireless communications has sparked great research enthusiasm. However, adaptive techniques are equally important for non-coherent counterparts although relatively less attention has been dedicated to. This letter studies the adaptive modulation for the energy detection (ED)-based non-coherent systems. Specifically, we consider a massive single-input multiple-output (SIMO) network, where a single-antenna user communicates with a base station (BS) with tens/hundreds of antennas. In particular, an optimization problem is formulated in order to find the signal-to-noise ratio (SNR) switching thresholds that maximize the average spectral efficiency (ASE). After deriving the SNR distribution and symbol error rate (SER), this problem is solved by applying the Lagrangian method. With switching thresholds, rate and power adaptation are made based on the instantaneous SNR. Numerical results indicate for the proposed scheme, there exists a trade-off between the target SER and ASE. That is, the ASE falls if one wishes to reduce the target SER. Under this circumstance, mounting more antennas can avoid the loss in ASE.
Highlights
M ASSIVE multiple-input multiple-output (MIMO) system, where a large number of antennas are deployed at base stations (BSs) to serve a relatively small number of users sharing the same frequency resources, has recently received a great deal of interest due to its huge potential gains [1]
We have developed an efficient way to design a joint multi-user constellation for energy detection (ED)-based non-coherent massive MIMO systems [7]
Channels of different transmit-receive pairs are modeled by independent Rayleigh fading
Summary
M ASSIVE multiple-input multiple-output (MIMO) system, where a large number of antennas are deployed at base stations (BSs) to serve a relatively small number of users sharing the same frequency resources, has recently received a great deal of interest due to its huge potential gains [1]. A low-complexity multiuser adaptive modulation scheme was proposed for uplink massive MIMO systems, which requires slow-varying large-scale shadowing information for the users [10]. Description number of antennas at the BS transmit power of the user information-bearing symbol channel vector from the user to the BS noise variance and channel variance candidate non-negative PAM constellations the j-th constellation size of the j-th constellation instantaneous SNR SER subject to instantaneous SNR PDF of γ subject to M and average SNR utilizes a lookup table as an index of the modulation type by using the feature of amplitude beam selection. This letter addresses the adaptive modulation for ED-based non-coherent massive SIMO systems. It is essential to effectively adapt to the channel variation
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