Electronics

How BAW addresses spectrum coexistence challenges in Wi-Fi 7


The transition from Wi-Fi 6 to Wi-Fi 7 has been a game changer, more than doubling the available frequency for wireless network. Traditionally, Wi-Fi has used the 2.4 GHz or 5 GHz super high frequency (SHF) radio bands. But Wi-Fi 7 introduces a new swath of spectrum at 6 GHz frequency, which enables faster connection and greater capacity for applications like video conferencing, 8K gaming, and AR/VR.

Furthermore, this spectrum offers an added advantage to its predecessors: the ability to leverage 320-MHz wide channels (rather than 160 MHz). While consumers may rejoice at the vast amount of increased bandwidth and improved speeds that they will eventually experience, technology developers must first overcome the coexistence challenges that Wi-Fi 7’s additional spectrum will bring.

Figure 1 The 6-GHz spectrum in Wi-Fi 7 brings new opportunities for consumers and new challenges for design engineers. Source: Infinity Business Insights

Challenges of Wi-Fi 7’s additional spectrum

The 6 GHz spectrum essentially doubles Wi-Fi capacity overnight. However, it also requires more power amplification, precision-switching, low-noise amplification, matching and packaging—resulting in added design complexity, router board space, and cost.

Figure 2 Here is how Wi-Fi 6 IEEE 802.11ax operation looks like with 2.4 GHz and 5 GHz bands. Source: Skyworks

Figure 3 Wi-Fi 7 IEEE 802.11be operation is shown with simultaneous use of 2.4 GHz, 5 GHz and 6 GHz bands. Source: Skyworks

Wi-Fi 7’s 6 GHz band can deliver over 40 Gbps of peak throughput, which is significant when considering the amount of quadrature amplitude modulation (QAM) it supports. QAM, used to translate digital packets into analog signals for seamless data transfer and to provide more spectrum usage efficiency, has been a part of Wi-Fi for more than a decade. However, while Wi-Fi 6/6E capped out at 1K QAM, Wi-Fi 7 supports up to 4K QAM. The challenge with higher-order modulation formats like 4K QAM is increased difficulty in transmitting and receiving data error-free. Thus, it requires higher RF performance.

Figure 4 A comparison is shown between Wi-Fi 6 and Wi-Fi 7 relating to 1024 vs 4096 QAM support. Source: Skyworks

Because the 6 GHz spectrum is traditionally unused in Wi-Fi devices today, it creates coexistence complexity in filtering and antenna management because it lies around the sub-7 GHz 5G band. Common filter technologies like low temperature co-fired ceramic (LTCC) and lumped element LC unfortunately fall short as they are too coarse and can block a significant amount of 6 GHz channels.

Moreover, this new band of spectrum will not support the operations of legacy devices that are based on the 2.4 GHz and 5 GHz spectrums. Given only routers with Wi-Fi 7 or Wi-Fi 6E support can operate on this band, it leads to limited device availability and interoperability issues with current Wi-Fi devices using the previous spectrums. This means that equipment and device providers will need to invest in new technologies for routers, laptops, and smartphones with Wi-Fi 7 capabilities, incurring more costs.

How BAW addresses Wi-Fi 7’s coexistence challenges

Wi-Fi 7 will bring great benefits, but its difficulties and complexities cannot be understated. To overcome these coexistence challenges, bulk acoustic wave (BAW) technology has arisen as a solution. BAW, an advanced filtering solution for mobile, radar and other communications systems, is a type of compact, cost-efficient RF filter that can be applied to several applications up to 6 GHz.

The frequency gap between 5 GHz and 6 GHz bands is minuscule, only about 50 MHz wide. Although traditional bandpass filters require a gap of about 200 MHz between channels to operate optimally, BAW filters can bypass this gap easily by enabling 110 MHz separation between 5 GHz and 6 GHz.

BAW filter technology can boost Wi-Fi 7 performance and reduce the impact of interference from other systems by providing high selectivity and low insertion loss necessary to operate on higher and more crowded frequency ranges. Then there is insertion loss, which is directly impacted by the device and a room’s temperature, making the device prone to fluctuation. Here, BAW filters come into play as they have temperature stability and can thus sustain performance.

Lastly, a growing trend among communications service providers (CSPs) is the emergence of connectivity-as-a-service (CaaS), an integrated solution that provides network connectivity across connectivity types. CaaS aims to streamline and simplify how operators deliver their services and new capabilities to customers. As part of this, more CSPs are looking to integrate solutions like 5G, IoT, edge and Wi-Fi 6 into a holistic service to improve customer outcomes. And with Wi-Fi 7 already on the horizon—and 6G anticipated to arrive within the next decade—the ability to integrate Wi-Fi 7 into this service will be critical.

Wi-Fi 7, 5G and 6G networks tout similar benefits: faster speeds, reduced latency, and more efficient spectrum use. At first glance, the choice between Wi-Fi and cellular for consumers and enterprises might seem black and white, with Wi-Fi being the clear winner for “untethered” connectivity needs. However, the pandemic has drastically shifted the connectivity needs of consumers, resulting in a demand for cellular connectivity outside the home to enable applications like telehealth and eLearning. So, ensuring the ability to use Wi-Fi and private network technology in a hybrid environment is critical.

BAW technology is uniquely situated to address the needs of 5G and 6G coexistence with Wi-Fi 7 because it manages the use of 6-GHz bands, which is frequently shared by all three networks. And it can isolate specific frequency bands used by wireless technologies to allow them to exist harmoniously within the same frequency while reducing interference between them. As a result, it delivers the enhanced and efficient performance needed for service providers to seamlessly deliver CaaS to stay competitive in the market.

Figure 5 Wi-Fi 7 calls for investment in new devices like routers, laptops, and smartphones. Source: Skyworks

Time is now for BAW and Wi-Fi 7

As Wi-Fi 7 products started shipping in 2023, it is anticipated many will transition directly from Wi-Fi 6 to Wi-Fi 7 to make the most out of its significantly increased transfer speeds, reduced latency, and increased network capacity. This mass upgrade to Wi-Fi 7, including by smartphone providers, will be a strong catalyst for the rest of the market to make the full transition to ensure their routers, security cameras, endpoint applications, PCs, and TVs are compatible with the latest smartphone devices.

To ensure providers are well equipped for this transition, they should look at investing in the latest BAW technology that has the capability to support 6GHz spectrum and below, and the ability to go higher as well.

Chung Liang Lee is global product marketing director at Skyworks Solutions Inc.

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