At present, non-orthogonal multiple access (NOMA) techniques have attracted broad attentions, since they could improve the throughput of cellular networks efficiently. However, the symbol error rate (SER) and bit error rate (BER) have not been studied comprehensively in the NOMA, even they play a key role in communication system control, e.g., power allocation. To address such an issue, this paper studies the SER and BER with consideration of the downlink/uplink transmission, the number of information streams, and the channel coding jointly. For analyzing the impact of channel coding, Gray coding is introduced for the downlink transmission. The derived SER and BER are given by closed-form expressions, by which the transmission performance could be evaluated efficiently. We also show an approximate SER/BER when the transmitter could employ Gray-coding. Additionally, associating with the derived closed-form expressions, we show that there exists no error propagation/error accumulation phenomenon when the successive interference cancellation (SIC) is adopted in signal demodulation, which is treated as a major drawback of SIC demodulation in the NOMA systems. Furthermore, by analyzing the encoding/decoding processes in the current NOMA works, a joint Gray-coding scheme is introduced to reduce the SER and BER in the downlink transmission effectively. Through simulations, we validate the correctness of the derived expressions of SER and BER from different aspects.

Broadcast and multi-cast communications are two important applications in quantum information science. Such applications guarantee the implementation of quantum information theory. In this paper, we propose two general schemes for the quantum broadcast and multi-cast communications to ensure that the central party (sender) can broadcast arbitrary single-qubit state to multiple receivers synchronously. Moreover, it is guaranteed that the information among the multiple receivers is different to satisfy the requirement in multi-cast communications. In particular, the proposed schemes indicate the probabilities, of which the multiple receivers obtain the quantum states successfully, could reach 1. We expect this works will shed some light for the prospective research on multi-party quantum communications and quantum cryptography.

Multicast-based quantum teleportation (QT) is extensively used in quantum information transmission where a sender sends different information to multiple receivers at the large distance through the quantum entangled channel. In this paper, we introduce the multi-output QT scheme, which deals with the situation that the synchronous transfer of the arbitrary m - and ( m +1)-qubit GHZ-class states from one sender to two receivers. Notably, the requirement about synchronous diverse information transmission is satisfied in our scheme with high efficiency. Moreover, we demonstrate the implementation of the special case of above quantum multi-output teleportation scheme on a sixteen-qubit quantum computer and a 32-qubit simulator provided by IBM quantum platform, then discuss it in four types of noisy environments, and calculate the fidelities of the output states.