Multiple Input Multiple Output (MIMO) networks operating in millimeter wave frequency band bring promising solutions for the increased demand of future generation networks in terms of data rate, signal quality, power optimization and computational complexity. A joint beam-forming (JBF) system working concurrently on source–relay–destination nodes leads to faithful delivery of signals by mitigating the effect of interferences. The traditional JBF designs in MIMO networks yield power wastage due to undesirable participation of intermediate relay nodes for message forwarding. The computational delay in beam-forming (BF) matrix update is tedious in traditional systems. This paper proposes a novel design of power-optimized JBF that facilitates optimum relay selection for solving power wastage issues. The selected relays co-operate in BF with the power constraint, and all other relays are powered down and enter into sleeping mode. Modified Cuckoo-Search Optimization (MCSO) algorithm is used for relay selection and minimum mean square error algorithm is used for BF matrix calculation. The proposed JBF is able to maximize Achievable Sum Rate (ASR) for optimum value of transmission power. The maximum power efficiency is achieved for distant communication with the aid of selected relays contributing to maximizing the ASR value. The proposed work minimizes the sum of mean square error and concurrently computes optimum time slot for BF matrix update, and hence computational delay is reduced. Thus a hybrid optimization for power and time in JBF design is achieved with relay selection and it can be widely used in future generation networks for high-quality and interference-free communication.

在毫米波频段内运行的多输入多输出（MIMO）网络为数据速率，信号质量，功率优化和计算复杂性方面的下一代网络需求的增长带来了有希望的解决方案。在源－中继－目的地节点上同时工作的联合波束成形（JBF）系统通过减轻干扰的影响，可以忠实地传递信号。MIMO网络中的传统JBF设计由于中间中继节点不希望参与消息转发而产生功率浪费。在传统系统中，波束成形（BF）矩阵更新的计算延迟很繁琐。本文提出了一种针对功率优化的JBF的新颖设计，该设计有助于优化继电器的选择以解决功率浪费问题。选定的继电器在BF与功率限制下协同工作，所有其他继电器均断电并进入睡眠模式。改进的布谷鸟搜索优化（MCSO）算法用于继电器选择，最小均方误差算法用于BF矩阵计算。提出的JBF能够最大化可实现的总速率（ASR），以获得最佳的发射功率值。借助有助于最大程度提高ASR值的所选继电器，可以实现远距离通信的最大功率效率。所提出的工作最小化了均方误差之和，并同时计算了用于BF矩阵更新的最佳时隙，因此减少了计算延迟。