Abstract-In this paper, the performance and system complexity of the candidate multiple access (MA) techniques for the next generation of cellular systems, namely, non-orthogonal multiple access (NOMA) (in this paper, we consider power domain MA as NOMA) and sparse code multiple access (SCMA), are investigated. To this end, for each MA technique, a resource allocation problem considering heterogeneous cellular networks (HetNet) is formulated. We apply successive convex approximation (SCA) method to each problem and obtain their solutions. The simulation results show that SCMA-based system achieves better performance than NOMA-based one at the cost of more complexity.

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In this paper, we consider a decode-and-forward (DF) relay-assisted diffusion-based molecular communication system inside one of the blood vessels of a human body with positive drift from transmitter to receiver. We use the normal approximation to the distribution of the number of received molecules and derive a closed-form expression for the end-to-end bit error probability of the system. We then propose an optimization problem that aims at minimizing the bit error probability of the system and solve it at the receiver nanomachine by an algorithm based on the bisection method to determine the optimal detection threshold. Furthermore, we study the impact of the system parameters, such as drift velocity, position of the relay node and number of allocated molecules on the performance of the system. The numerical results show that with a constant molecular budget, DF relying strategy can considerably improve the system performance.

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Designing energy-efficient delay-aware communication networks has become an inevitable trend in 5G wireless networks. In this letter, we present an energy-efficient and delayaware cross-layer resource allocation in SISO wireless systems. To achieve this goal, we apply the notion of effective energy efficiency (EEE), defined as the ratio of the system effective capacity (EC) over the total power consumption. Unlike previous works, we introduce a new average power consumption model which accounts for the data link layer, allowing for the probability of emptying the buffer during the transmission timeframe. This leads to a new definition of EEE, which results in better performance in terms of both EEE and EC.

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