Performance of Quantized Random Beamforming in Delay-Tolerant Machine-Type Communication

Abstract

Machine-to-Machine (M2M) communication represents a new paradigm for mobile cellular networks, where a massive number of low-cost devices requests the transfer of small amounts of data without human intervention. One option to tackle this problem is obtained by combining Random Beamforming (RBF) with opportunistic scheduling. RBF can be used to induce larger channel fluctuations and opportunistic scheduling can be used to select M2M devices when their overall channel quality is good. Traditional RBF does not fulfill M2M requirements because overall channel quality needs to be tracked continuously. In order tackle this limitation, a novel codebookbased RBF architecture that identifies in advance the time instants in which overall channel quality should be reported, within a coherence time window, is proposed. This opportunistic feedback mechanism reduces signaling overhead and enables energy saving at M2M devices. A simplified methodology is presented to evaluate the system mean data rate, using for this purpose closed form formulas derived from SNR distribution approximations. Results reveal that the performance loss that is experienced for introducing the proposed modifications to traditional RBF scheme is negligible. The concepts analyzed in this paper provide useful insights, and show that codebook-based RBF with simplified opportunistic scheduling algorithms is an excellent combination to provide wide-area M2M services with low-cost devices and limited signaling overhead.

Enhanced Orthogonal Frequency-Division Multiplexing With Subcarrier Number Modulation

“…In other words, with an increasing M , it is less likely that OFDM-SNM has a higher rate than plain OFDM. In particular, M should satisfy the condition M ≤ N 2 N −1 (38) in order to achieve (36). Therefore, we can list all possible combinations of N and M in Table V.…”

Hybrid beamforming algorithm using reinforcement learning for millimeter wave wireless systems

“…where F rf and F bb should be selected from the feasibility set of the analog beamforming and digital precoding matrices, respectively. In this paper, the columns of the analog beamforming matrix are codebook-based, such that each of the coefficients that corresponds to the different antennas can only take discrete values from a uniform quantization set [7]. On the other hand, the coefficients of the digital precoding matrix are not restricted to belong to a codebook and, in principle, can take any complex number such that F bb F = 1 is verified.…”

“…using a similar procedure to the one utilized in (2). The data rate that is achievable with the hybrid beamforming algorithm that is proposed for the given channel state H, when F bb and F rf are defined according to (7) and (5), respectively, can be evaluated with the aid of the Shannon's formula, i.e.,…”

“…In this paper, we present a novel hybrid beamforming algorithm that seeks the maximization of the achievable sum data rate of a mmWave Massive MIMO system. For this purpose, the digital precoder and analog beamformer to be utilized in transmission are jointly determined, assuming that the weights of the analog beamformer can only belong to a set of uniformly quantized phase shift values [7]. More precisely, it is assumed that for a given analog beamformer, an equivalent lower-dimension wireless channel can be obtained, whose capacity-achieving transmit digital precoder can be derived using Singular Value Decomposition (SVD).…”

Low-Overhead Joint Beam-Selection and Random-Access Schemes for Massive Internet-of-Things with Non-Uniform Channel and Load

“…Unfortunately, centralized MIMO schemes incur high overhead due to the need of collecting Channel State Information (CSI) from all users [2][3][4]. Recently, we proposed in [5] an UL random-access protocol using Pseudo-Random Beamforming (PRBF) [6] to exploit the performance gain of MIMO with limited centralized control. The idea is to let BS use multiple receiving beams at each time following a pseudo-random sequence.…”