A Survey: Non-Orthogonal Multiple Access with Compressed Sensing Multiuser Detection for mMTC <s> Pilot Transmission Data Transmission <s> We introduce a "one shot" random access procedure where users can send a message without a priori synchronizing with the network. In this procedure a common overloaded control channel is used to jointly detect sparse user activity and sparse channel profiles. The detected information is subsequently used to demodulate the data in dedicated frequency slots. We analyze the system theoretically and provide a link between achievable rates and standard compressing sensing estimates in terms of explicit expressions and scaling laws. Finally, we support our findings with simulations in an LTE-A-like setting allowing "one shot" sparse random access of 100 users in 1ms. <s> BIB001 </s> A Survey: Non-Orthogonal Multiple Access with Compressed Sensing Multiuser Detection for mMTC <s> Pilot Transmission Data Transmission <s> In this paper, we study random access for machine-type communications based on a multiple access scheme that exploits different channel state information (CSI) from active devices under frequency-selective fading, which is called channel division multiple access (ChDMA). In ChDMA, in order to use a low-complexity compressive sensing (CS) algorithm for multiuser detection (MUD) with a high transmission rate, we propose to use index modulation. Since the CSI is used as a signature for MUD, the CSI estimation becomes crucial. For the CSI estimation, pilot transmission can be considered where each active device randomly chooses a pilot from a set of pre-determined pilots. Since the CSI estimation suffers from pilot collision in this case, we propose multiple pilot transmissions and show that a low probability of collision can be achieved. A CS-based approach is derived not only to estimate the CSI, but also to detect randomly selected multiple pilot signals by exploiting the sparsity of active devices over frequency-selective fading channels. <s> BIB002 </s> A Survey: Non-Orthogonal Multiple Access with Compressed Sensing Multiuser Detection for mMTC <s> Pilot Transmission Data Transmission <s> In machine-type communications (MTC), a number of devices are present in a cell, but only a few of them attempt to access by sending preambles or pilots. For the sparse activity of devices, compressive sensing (CS) can be applied for joint detection of active devices and estimation of channel profiles. In this paper, a theoretical connection between pilots and the coherence of a CS measurement matrix is revealed for CS-based detection and estimation. Then, the Zadoff-Chu (ZC) and the power residue (PR) sequences are studied as potential candidates for pilot signals in CS-based random access. It is also shown that the CS measurement matrices from the ZC- and the PR-based pilots have theoretically bounded low coherence, which presents a theoretical guarantee of reliable recovery performance. Simulation results demonstrate that the proposed deterministic pilots outperform random binary and complex-valued pilots for CS-based random access in MTC. <s> BIB003
Pilot block 1 Pilot block T p Data block 1 Data block T d Fig. 11 : Frame structure of channel division medium access transmission BIB002 BIB001 A similar scheme is also adopted in BIB003 , in which the number of possible Zadoff-chu and power residue based pilot sequences are calculated. For Zadoffchu the possible number of sequences in sequence set is P = (N s − 1)(N s /V t + 1), where N s is length of sequence, and V t is the smallest integer greater than the number of channel taps. For power residue based, P = (R − 1)N s , where R is a positive integer which divides N s − 1. A summary of the CS based medium access schemes is presented in Table  3 .