How to cram huge data streams into a compact smartphone? Qorvo experts offer advice

As global demand for mobile data continues to grow and user expectations for performance continue to rise, smartphone and other mobile device manufacturers are responding by delivering faster Wi-Fi performance.

整个行业正在迅速迁移到 IEEE 802.11ac Wi-Fi 标准，与上一代标准 802.11n 相比，该标准在性能上有着显著提升，其他改进功能包括更多的空间数据流（多达 8 个 MIMO）、更宽的通道（高达 160 MHz）和更高阶的调制（高达 256 QAM）。在手机领域，越来越多的制造商开始部署 2x2 MIMO，单个数据流性能因此提升多达两倍，采用 802.11ac 标准时最大数据速率在理论上可以达到 1.69 Gbps。

MIMO and 802.11ac present new challenges for engineers designing mobile devices. Designers must cram an additional Wi-Fi link into the already crowded space inside ultra-thin handsets while managing design complexity and supporting more demanding performance requirements.

Specifically, about 60% of a smartphone’s internal space is typically dedicated to the battery, ensuring the device has adequate battery life. All other components must be crowded into the remaining 40%, including processors, modems, sensors, and cellular and Wi-Fi front ends. As device complexity continues to rise, so does the difficulty of fitting all of these components into the available space. For example, each generation of flagship smartphones supports more LTE bands than the previous generation. Compared to 3G phones from a few years ago, today’s 4G smartphones may need to support up to 3 times more RF bands, while maintaining roughly the same form factor.

In addition to tight space constraints, engineers must also contend with the higher performance requirements imposed by the 802.11ac standard. Compared to previous Wi-Fi standards, 802.11ac front ends must provide higher linearity while maintaining low insertion loss and low power consumption. Throughput can be increased by 33% due to the increase in maximum modulation complexity from 64 QAM in 802.11n to 256 QAM in 802.11ac. However, it also requires higher linearity (lower constellation error), which means meeting tighter dynamic error vector magnitude (EVM) requirements. In 802.11ac, the maximum system EVM allowed for the transmit device is -32 dB (when using 5/6 coding rates), compared to only -28 dB in 802.11n. Because system requirements include the contribution of the Wi-Fi chipset, 802.11ac Wi-Fi front ends must achieve lower EVM.