Tips and Trends: Small Cell 5G Systems

The role of small cells is increasing with each “G”. The appetite for more data speeds and capacity is driven by consumers and businesses. These tiny base stations are the carriers’ go-to solution to ensure quality of service in the outer edge of the network is met. Today’s growth is also attributed to LTE-A Pro and 5G services. In this post, we provide the latest insights on the small cell market trends, RF front-end challenges and practical solutions to meet user and manufacturer needs.

Small Cells Market Update 2019

小型电池部署已转向大规模致密化，这增加了一系列位置的运营商网络的容量，并解决了消费者和企业移动宽带需求的上升。由于有效地满足所有5G用例所需的小型电池部署数，5G将使致密化挑战更加令人生畏。

在一个小型电池论坛市场更新中，78个全球移动运营商被要求列出他们致密的所有原因。最重要的司机与增加的能力和成本有关。

• 40％的运营商放置了密集的能力，以支持提高经验质量作为最大原因，因为这会影响减少衰退和客户满意度。
• 3.8% said reducing overall cost of capacity as the reason to invest in small cells.

移动的network operators (MNOs) are looking to support higher levels of data usage and rising customer expectations of a high-quality experience. They must do this profitably while servicing many markets. Small cell densification helps achieve this goal while keeping cost of ownership at a manageable level.

根据这一点小细胞论坛，到2025年的小型电池部署和升级将达到1025万无线电，不含840万。企业，550万台将是最大的，其次是城市部署。（见图1）

Figure 1. (source: Small Cells Forum)

2017年至2019年的同比增长40％，可归因于中国市场的能力致密化。2020年及以后，由于许多企业用例，市场保持稳定的20％增长率（即制造自动化，物联网，航运港等）。虽然北美的小细胞的致密化已经缓慢，但前进我们将看到与公民乐队无线电服务的部署增加（CBRS 3.5 GHz）。

The majority of non-residential indoor small cells are public-facing in the enterprise environment supporting private enterprise activities. Outdoor small cells are servicing MNO public networks in urban, suburban or rural environments. Most of these indoor small cells are driven by 2.4 GHz and below frequencies, while the China market drives the outdoor small cell growth. In the 5G era, much of the small cell market growth will be related to industrial and Internet of Things services.

Figure 2. (source: Small Cells Forum)

5G网络的小电池

小细胞的目的是通过增强网络容量来减轻宏观小区上的负载并提供扩展的覆盖范围。使用小细胞仅限于致密区域和室内（即体育场，商场等），其中宏观信号渗透不足。为此效果，小细胞一直非常受到4G LTE覆盖和容量增强的欢迎。现在，随着市场转换到5G，全新的频谱是在2.6到5 GHz范围内的超过100MHz的连续带宽开口。此额外频谱将支持高数据率和新的市场机会。此外，高阶多输入多输出（MIMO）是标准宏体系结构，实现更高的吞吐量和数据速率。小细胞将继续为5G容量增强与室内覆盖范围发挥关键作用。

Traditionally small cells have been deployed in a 2-transmit/2-receive (2T/2R) MIMO configuration but with 5G, that architecture will be expanded to 4T/4R for increased throughput. These small cells are networked with 5G macro cells that use massive MIMO leveraging AAS (active antenna systems) in configurations of 32T/32R and 64T/64R. This maximizes spectral efficiency (more bits per Hz) for operators by providing the optimal balance between user coverage and capacity.

Massive MIMO自4G LTE-A PRO和5G标准版本以来一直是网络的组成部分（参见图3）。对于5G，MNOS将以比前几代更快的速率部署小单元，因为致密化是最重要的。

Figure 3

作为显示在图3中,网络容量跳跃with LTE-A due to massive MIMO and small cell integration. The capacity jumps even more with 5G. Beamforming and advanced antenna array architecture also helps reduce co-cell interference. This new architecture design increases bandwidth, provides a more focused energy, reduces interference and provides a capacity lift via small cells.

RF前端设计挑战和解决方案

典型的小单元由用于许可蜂窝和LTE未许可（LTE-U）带的无线电组成。此外，在网络边缘的小小区中有一个推动IOT实现 - 用于家庭，业务和汽车通信。

那么，制造商和供应商在开发小型电池系统时造成哪些挑战？低资本支出，产品差异化，持续最佳的性能，以及市场快速上市的挑战厂家面临。它们还面临频谱加法与致密化以提升能力之间的最大权衡。看看图4的高级视图，了解如何用各种RF前端解决方案解决设计挑战。

Figure 4

Increase in number of bands.Just like the mobile device has increased in complexity, the small cell must also become more multifaceted. There has also been an increase in the number of bands, now up to 52. Frequency bands are also moving above 3 GHz with new 5G NR bands such as n77, n78 and n79. The incorporation of additional bands in the small cell and the adoption of 4T4R MIMO radio configuration help enable carrier aggregation (CA) to further increase network capacity and data speed. Having a large portfolio of RF front-end components offering multi-band solutions from one source is optimal. This can decrease design time and vendor qualification for the small cell manufacturer.

Larger bandwidth requirements.如前所述，对能力扩展的需要对更多频谱至关重要。无线电容量必须增加以满足5G的高数据速率预期。为了满足5G中的无线电容量，小型电池前端需要使用宽带放大，因为窄带装置不再足够。拥有包括LTE-A PRO和5G频段的RF产品组合非常重要，因为它为小型电池制造商提供了设计和库存保持单元（SKU）灵活性。此外，提供更宽的带宽RF组件有助于满足具有较少分立组件的带宽要求，减少设计时间和上市时间。

乐队和标准之间的共存。Carriers must meet the capacity and data rate requirements for 4G LTE, 5G and unlicensed bands. Small cell manufacturers must design units that mitigate interference between all these bands and standards (i.e. LTE, 5G, Wi-Fi, etc.). These interferences can occur inside small cell units and around the unit. Using BAW filters is the best defense in mitigating interference, as these provide steep band edge skirts, are small in size and can meet high power requirements without damage.

输出功率正在增加。Recently there has been a push to increase average PA output power levels. Small cell manufacturers are requesting the higher RF PA output power levels to add design flexibility. This helps them scale the design to different market segments requiring better coverage vs. capacity. But, this requirement does add a level of complexity for PA designers, as they need to increase the PA output power while maintaining a high level of linearity and efficiency. Recently, PA output power requirements have risen approximately 3 dB. The increased power level limit raises the possibility of out-of-band distortion, making it difficult for manufacturers to meet spectral emissions mask requirements. Finding RF vendors with PA products that meet these high-power requirements helps reduce design time and can reduce components in the RF chain.

Figure 5

A PA is most efficient near saturation. However, as seen in Figure 5, near saturation a PA can generate out-of-band distortion components. Using a design technique known as digital pre-distortion (DPD) the PA can run nearer to saturation with out-of-band distortion minimized. DPD is a software-based design method for removing distortion using digital signal processing techniques. It allows a PA to be optimally designed for lower power dissipation but achieve similar output power and still maintain the required spectral mask requirements as a linear PA. This technique has been around for several years and is widely used in wireless infrastructure applications. Many RF component suppliers offer both DPD and non-DPD components to allow small cell manufacturers design and SKU flexibility.

尺寸，重量和功耗（交换）需要更有效的设备。由于小型细胞成为景观的一部分（即在灯柱，City Bechches，在人孔盖等），需要更小的高效部件。如上所述，保持检查和线性度的失真优化有助于获得更高的输出功率并实现交换。

通常，小型电池制造需要最小的RF PA的功率增加35％的功率增加效率（PAE），因为这提供了低功耗和低运营成本。单位大小由最终用户放置驱动，如公园长凳或签名。为满足客户的表格因素预期，RF组件制造商必须创建更多的线性和功率有效的设备。通过这样做，他们可以满足尺寸限制，功率输出和较低的功耗要求。

一起建立未来

小型电池演进有许多驱动因素，包括5G致密化卷展栏。小型电池变得越来越多程度，集成更多的频带，带宽，更高的线性度和效率，以帮助MNO获得急需的投资回报率。Qorvo通过提供广泛的PAS，LNA，滤波器，双工器，开关和前端模块来帮助指导小型电池供应链设计者和载体通过这一进化。有关我们小型电池组合的完整列表点击这里。

Below is a non-exhaustive list of Qorvo RF front-end components and block diagrams for FDD and TDD small cell applications.

图6.小型电池FDD和TDD框图

Table 1

学习用小细胞解决网络拥塞和效率

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