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The current mobile communications could not satisfy the explosive data requirement of users. This paper reviews the frontier technology of software definition networks (SDN) of 5G and 6G, including system architecture, resource management, mobility management, interference management, challenges, and open issues. First of all, the system architectures of 5G and 6G mobile networks are introduced based on SDN technologies. Then typical SDN-5G/6G application scenarios and key issues are discussed. We also focus on mobility management approaches in mobile networks. Besides, three types of mobility management mechanism in software defined 5G/6G are described and compared. We then summarize the current interference management techniques in wireless cellular networks. Next, we provide a brief survey of interference management method in SDN-5G/6G. Additionally, considering the challenges, we discuss mm-Wave spectrum, un-availability of popular channel model, massive MIMO, low latency and QoE, energy efficiency, scalability, mobility and routing, inter operability, standardization and security for software defined 5G/6G networks. [ABSTRACT FROM AUTHOR]

A 3-phase Golay complementary triad (GCT) is a set of three sequences over the 3-phase alphabet {1, ω, ω2}, where ω = e 2 π − 1 3 is a 3rd root of unity, whose aperiodic autocorrelations sum up to zero for each out-of-phase non-zero time-shifts. Recent results by Avis and Jedwab proved the non-existence of 3-phase GCTs of length N ≡ 4 (mod 6). In this paper, we introduce 3-phase Z-complementary triads (ZCTs) and almost-complementary triads (ACTs). We present systematic constructions of 3-phase ZCTs for various lengths including the case when N ≡ 4 (mod 6). We also analyse the peak-to-mean envelope power ratio (PMEPR) upper-bounds of the proposed ZCTs and ACTs. [ABSTRACT FROM AUTHOR]

In this work, we investigate a massive multi-input multi-output two-way relaying system, where K pairs single-antenna users exchange information through a relay station equipped with N ( N ≥ 2 K ) antennas, employing the amplify-and-forward protocol and maximum ratio combining/maximum ratio transmission beamforming. Considering Rician fading channel with imperfect channel state information (CSI), we study the achievable sum rate and energy efficiency (EE) performance of the considered system. Firstly, we obtain the asymptotic results of the achievable sum rate and the EE, assuming a general power scaling scheme. It is shown that when N → ∞ , the pilot sequences' power, i.e., P P , each user's transmit power, i.e., P U , and the relay station's transmit power P R can be scaled down proportionally to 1 / N a , 1 / N a and 1 / N b , respectively, where a ≥ 0 and b ≥ 0 . Specifically, when perfect CSI is known and Rician factor κ = 0 , our derived results reduce to the existing results in Rayleigh fading channel. Furthermore, the closed-form expressions of the achievable sum rate and EE are obtained approximately. Finally, simulation results are provided to confirm the validity of our analysis. [ABSTRACT FROM AUTHOR]