The Performance of Successive Interference Cancellation in Random Wireless Networks

We present a successive interference cancellation (SIC) scheme for a multicarrier (MC) DS CDMA system. In every subband, the SIC receiver successively detects the interferers' signals and substracts them from the user-of-interest. A comparison is made among SIC, matched filter detection with an equal gain combiner (MF-EGC), matched filter followed by maximal-ratio combining (MF-MRC) and minimum mean-squared error (MMSE) receivers with optimal tap coefficients. For this latter receiver, we determine the performance both when the number of taps equals the processing gain, denoted by N, and when the number of taps is roughly one-half of the processing gain. By analysis and simulation, it is shown that the SIC has better ability to suppress multiple-access interference (MAI) than do MF and [N/2]-tap MMSE in single carrier (SC) CDMA, and MF-EGC, MF-MRC and [N/2]-tap MMSE in MC CDMA, and this translates to increased capacity and better fading resistance. Further, SIC and N-tap MMSE yield approximately the same performance in SC CDMA, but SIC has a poorer performance than does an N-tap MMSE in MC CDMA. In addition, we derive results for the performance degradation that a SIC scheme experiences in MC CDMA due to both phase and timing tracking errors. It is shown that with small tracking errors, SIC can still retain a performance advantage over MF-EGC and MF-MRC, although the advantage of SIC decreases with increasing tracking errors.

In DS/CDMA systems, overcoming near/far effects and fading is imperative for satisfactory performance. One way to combat the near/far effect is to use stringent power control, as is done in most of the commercial systems. Another approach is Multi-User Detection (MUD). In addition to mitigating the near/far effect, MUD has the more fundamental potential of raising capacity by canceling Multiple Access Interference (MAI). This paper analyses the convergence behavior and performance of successive interference cancellation (SIC) for CDMA systems. This analysis will be generalized for Parallel Interference Cancellation (PIC) also. In this paper a Hybrid Interference Cancellation (HIC) receiver is designed by combining the successive and Parallel Interference Cancellation algorithms, so that the advantages of both the schemes are utilized effectively. The Hybrid Interference Cancellation scheme results in a simple, faster and reliable receiver. With the help of simulations, it is shown that this hybrid approach outperforms the other Multi-User Detection schemes.

This research aims to optimize the performance of Successive Interference Cancellation (SIC) in Power Domain Non-Orthogonal Multiple Access (PD-NOMA) technology by applying spatial concepts through the use of beamforming techniques. User clustering is a key element in achieving this goal, and this research applies various supervised machine learning classification algorithms including Decision Tree, K-Nearest Neighbors (K-NN), Support Vector Machine (SVM), Random Forest, Logistic Regression, and Naive Bayes. The experimental results show that Random Forest achieves the highest accuracy in classifying users, followed by Decision Tree. In addition, in measuring performance using ROC (Receiver Operating Characteristic) and AUC (Area Under the Curve) curves, Decision Tree and Random Forest achieved the best results as well. While in terms of experimentation process time, decision tree has a faster time than random forest. Overall, Random Forest and Decision Tree algorithms are suitable for the task of user clustering in the context of PD-NOMA which utilizes the spatial concept of user to Base Station (BS).

In this paper, we present mathematical frameworks for error performance analysis in interference limited networks such as cellular networks. Due to the increasing irregularity in the spatial deployment of nodes in the emerging heterogeneous cellular networks (HCNs), we employ stochastic geometry approach by abstracting the node locations as a homogeneous Poisson point process (PPP). First, we characterize the average error probability of an intended communication link with a given transmitter-receiver separation, which is subject to interference from these Poisson distributed nodes. More specifically, we develop uniform approximation (UA), which is highly accurate over the whole range of signal-to-interference ratio (SIR) and hence, serve as an alternative to existing complex analytical results. Error probability UAs for both single-antenna and maximal ratio combining (MRC) receivers are derived in this paper. Next, we evaluate the average error probability of any typical user in the network, which is served by the node providing the maximum received power. Mellin-transform based method is proposed in this case, which often yield closed-form solution. An example of BPSK modulation is given in the paper.

Recently, lattice-reduction (LR) has been proposed to improve the performance of linear and successive interference cancellation (SIC) detectors and precoders in MIMO systems. It is proved that LR-aided linear detectors collect the same diversity order as that exploited by the ML detector but with much lower complexity when perfect channel state information (CSI) is assumed to be available. However, in practice, CSI is always contaminated by channel estimation error and feedback quantization error. In this paper, we proposed MMSE based LR-aided robust linear and SIC detectors and MMSE based LR-aided (robust) linear precoder and (robust) Tomlinson-Harashima precoder (THP) which are capable of improving the BER performance in the context of imperfect CSI. Furthermore, we find that the performance improvement of LR-aided nonlinear method in SIC detectors at receiver is more pronounced than that in THP at transmitter.

To increase the rate of transmission, it is natural to consider the multilevel modulations. However, in non-orthogonal multiple access (NOMA), the straight application of multilevel modulations can be hardly made due to the severe effect of the superposition. Recently, to mitigate the destructive impact of the superposition, polar on-off keying (POOK) and quadrature POOK (QPOOK) have been proposed in [1-2]. This paper expands such concept to multilevel modulations, e.g., polar 4-ary on-off keying (P4OOK), which is compared to the 4-ary pulse amplitude modulation (4PAM). It is shown that first, for the strong channel user with binary phase shift keying (BPSK), the BPSK/P4OOK NOMA performance is better than the perfect successive interference cancellation (SIC) performance of BPSK/4PAM NOMA, and second, for the weak channel user, the BPSK/P4OOK NOMA performance is comparable to the perfect SIC BPSK/4PAM NOMA. In result, P4OOK could be considered for NOMA.

The full-duplex (FD) cooperative nonorthogonal multiple access (NOMA) achieves a superior throughput over the conventional half-duplex (HD) cooperative NOMA, wherein the strong users (SUs) with good channel conditions can act as an FD relay node for the weak users with poor channel conditions. However, the energy efficiency (EE) of a cooperative NOMA may be degraded due to the additional power consumption incurred at the SUs. We are, therefore, motivated to investigate the EE maximization problem of an FD cooperative NOMA system. More importantly, we investigate the “signal-to-inference-noise ratio gap reversal” problem of cooperative NOMA systems, which imposes successive interference cancellation (SIC) performance degradation at the SUs. This problem has not been documented in the existing cooperative NOMA literature. A low-complexity algorithm is proposed for maximizing the system's EE while guaranteeing a successful SIC operation. Our numerical results show that the proposed algorithm achieves both a higher EE and throughput over the existing HD cooperative NOMA and nonadaptive FD cooperative NOMA. More importantly, the proposed scheme guarantees a successful SIC operation at the SUs.

In this paper, we describe amplitude estimation algorithms for the Walsh traffic channels in the downlink of Interim Standard 95 (IS-95). The parameter estimate is designed to improve the performance of a successive interference canceller (SIC) by providing greater reconstruction accuracy. A feature of the IS-95 downlink that makes amplitude estimation difficult is that during lowered voice activity levels, bit repetition occurs with a corresponding drop in the symbol energy for a frame of data. As a result, the amplitude level cannot be assumed to remain constant and should be taken into account during signal reconstruction in the SIC. We explore various algorithms for estimating the nominal Walsh traffic channel amplitude level. The distinguishing characteristic of the different techniques is the type of a priori knowledge employed in the estimation. For example, one parameter that may need to be estimated is the bit repetition multiple using a rate determination algorithm.

The growing demand for high-speed data, quality of service (QoS) assurance and energy efficiency has triggered the evolution of 4G LTE-A networks to 5G and beyond. Interference is still a major performance bottleneck. This paper studies the application of physical-layer network coding (PNC), a technique that exploits interference, in heterogeneous cellular networks. In particular, we propose a rate-maximising relay selection algorithm for a single cell with multiple relays based on the decode-and-forward strategy. With nodes transmitting at different powers, the proposed algorithm adapts the resource allocation according to the differing link rates and we prove theoretically that the optimisation problem is log-concave. The proposed technique is shown to perform significantly better than the widely studied selection-cooperation technique. We then undertake an experimental study on a software radio platform of the decoding performance of PNC with unbalanced SNRs in the multiple-access transmissions. This problem is inherent in cellular networks and it is shown that with channel coding and decoders based on multiuser detection and successive interference cancellation, the performance is better with power imbalance. This paper paves the way for further research in multi-cell PNC, resource allocation, and the implementation of PNC with higher-order modulations and advanced coding techniques.

The paper introduces an analytical tool to find the large-system performance of a multistage linear partial parallel interference cancellation (PPIC) receiver using the moments of the eigenvalues of the covariance matrix for a code division multiple access (CDMA) system over a frequency-flat fading channel. The figure of merit to evaluate the performance is the signal-to-interference-plus-noise ratio (SINR) that is calculated under a large-system condition. In this case, the number of active users and the processing gain tend towards infinity while their ratio is a fixed value. It is shown that the large-system performance is a function of the system load, the partial cancellation factor (PCF), the number of interference cancellation stages, the signal-to-noise ratio (SNR), and the received powers of the interfering users. Furthermore, for practical applications, the physical meaning of the large system is described by numerical simulations.

The benefit of a Full-Duplex Single-Channel (FDSC) system is the double throughput because it can transmit and receive simultaneously at the same time and on the same frequency. However, the expense of FDSC system is on the very strong self-interference signals due to the leakage of transmitting signals that interfere the receiving signals. Moreover, for MIMO systems, the problem of interferences is severely considered due to multiple transmitting and receiving antennas. So far in literatures, there have not been any suitable techniques presented to reduce the self and mutual interferences for FDSC MIMO systems. This paper present the performance of self and mutual interference cancellation by utilizing the mutual coupling model. The interferences can be eliminated by using pre-known interferences that are the mutual coupling signals. The results indicate that the channel capacity performance of the proposed technique can significantly be improved due to the reduction of the interference power. The measurement results indicate that the proposed FDSC MIMO system can suppress the self and mutual interferences signals with the reduction of 29.84 dBm received power.

In this paper, the performance of parallel interference cancellation (PIC) multiuser detector in orthogonal frequency division multiple access (OFDMA) mobile communication systems is investigated. In multiuser systems, the multi-user interference (MUI) degraded the system performance, especially in near-far effect environments. The PIC scheme is proposed to reduce the MUIs and to improve the bit error rate (BER) performance for uplink OFDMA systems. Simulation results show that under the near far problems for both block sub carrier assignment scheme (BCAS) and block-interleaved sub carrier assignment scheme (ICAS), the PIC scheme can improve the BER performance for all users.

In this paper, the performance of parallel interference cancellation (PIC) multi-user detectors in orthogonal frequency division multiple access (OFDMA) mobile communication systems is investigated. In multi-user systems, the multi-user interference (MUI) degraded the system performance, especially in near-far effect environments. An adaptive weight partial PIC (AWPPIC) scheme is proposed to reduce the MUIs and to improve the bit error rate (BER) performance for uplink OFDMA systems. Simulation results show that under the near far problems for block sub carrier assignment (BCA) scheme, the AWPPIC scheme can improve the BER performance no matter what the system load is.

Device-to-Device (D2D) communications is expected to gain importance in future cellular networks for spectrum efficiency. However, dealing with the interference in simultaneous D2D and cellular transmissions is a significant challenge. In this paper, the problem of optimal pairing of D2D and CU transmissions is addressed in order to control interference from CU to D2D receiver and D2D transmitter to Base Station (BS). Different from the literature, the BS is able to perform Successive Interference Cancellation (SIC) in addition to Single User Detection (SUD). The performance of solutions based on mixed integer linear programming, Hungarian algorithm and simple matching algorithms are compared. Through the simulation results, the effectiveness of SIC is demonstrated in terms of the overall network throughput.

Coordinated multi-point (CoMP) transmission is an effective means of improving network throughput in heterogeneous cellular networks (HetNets). However, its performance is seriously weakened if imperfect coordination happens between base stations (BSs). Many prior CoMP works do not consider inter-cell overhead message delays such that a seemingly astonishing CoMP throughput gain is attained. In this paper, the quantization error and delay that actually exist in overhead messages was modeled and we developed a much tractable SIR model based on the stochastic geometry framework. We proposed adaptive CoMP that is applied to downlink zero-forcing beamforming (ZFBF) and it can mitigate the interference from the coordinated cells with delayed overhead messages. The bounds on the complementary cumulative distribution function (CCDF) of the SIR of a user are characterized such that the average throughput of a user is able to be analytically evaluated. Numerical results show that the proposed adaptive CoMP scheme can make the throughput gain very robust to the overhead delay and thus significantly increase the throughput even when BSs are not perfectly coordinated.