What are the rf front-end methods for implementing 1gbps download speed on smartphones?

Some people may ask, "Why do we need 1 Gbps download speed? Is the current download speed not fast enough?"

Let's face it: we all hate to see the buffering symbols on the phone, and we always want more data. Operators also want users to have faster download speeds—the faster they get data, the faster they can transfer these valuable spectrum resources to another user.

In the March 2017 report, Cisco noted that the current average mobile network connection speed is about 6.8 Mbps, which is a far cry from 1 Gbps. No wonder we will see the buffer symbol rotation on the phone when downloading.

So how do you achieve 1 Gbps download speed and upload speed on your smartphone? Once you understand the 1 Gbps enabling technology and the available RF components, you'll find a simple incremental path to achieve the Gigabit data rate of your phone.

Steps to achieve 1 Gbps: What is needed

First, let's be clear: the road to 1Gbps is not a one-off. Instead, it consists of many small steps that go in the right direction.

Here is some background information. The RF Front End (RFFE) is still one of the most critical aspects of mobile handset design. Extended carrier aggregation (CA) capabilities, more complex antenna architectures, antenna tuning, higher-order modulation schemes, and increased spatial streams all make the RFFE design more complex. In addition, the transition from LTE-Advanced to LTE-Advanced Pro to 5G New Radio (NR) has greatly increased the complexity of RFFE. In the past few years, advanced smartphones have evolved from a small portion of the RF band in a cell phone to include up to 34 bands.

More topics but what do you need most to reach 1 Gbps? Here are some basic drivers:

1

High-order modulation On the downlink, switching from 64 QAM to 256 QAM increases the speed of a single 10 MHz channel from 75 Mbps to 100 Mbps.

2

Carrier aggregation. Multiply 100 Mbps by the number of aggregated component carriers. 3-5 Downlink (DL) CA is now available, thus allowing up to 500 Mbps.

3

4x4 MIMO (multiple input/multiple output). With 4-antenna spatial diversity in LTE, the DL component carrier (CC) can be effectively extended to 4 channels.

real

The most straightforward approach to 1 Gbps is to use a 3DL CA with 4x4 MIMO on 2 of the 3 component carriers. This is equivalent to 10 data streams in 3 frequency bands. In the case of 256 QAM, it is 10 x 100 Mbps - equal to 1 Gbps. With a high-performance chipset, 3CA with 4x4 MIMO and 256 QAM capabilities can be enabled in the phone, but the RFFE must be usable.

Due to antenna size limitations, the low band is not optimal for 4x4 MIMO, and the band supporting 4x4 MIMO needs to be in one of the following frequency ranges:

1

Medium frequency band (MB)

2

High frequency band (HB)

3

Ultra high frequency band (UHB, about 3.5 GHz)

4

5 GHz range using Licensed Access (LAA)

If we start with the network and RFFE architecture available in our current handsets, it will be difficult to make UHB or LAA a ready-to-use option, so we will focus on adding 4x4 MIMO to the mid to high band.

Benchmark RFFE in today's smartphones

LTE telephony has moved a step toward this 1 Gbps target, primarily by using multiplexers to increase the number of CA transmit (Tx) and receive (Rx) paths and/or add more to support multiple bands. antenna. Many mobile phones now have four radio antennas that do not include Wi-Fi antennas, but do not necessarily support 4x4 MIMO.

The following is a simple front-end design using 4 antennas (2 main antennas and 2 diversity/MIMO antennas). This design is a good benchmark for several smartphone options on the market today. It is a simple high/medium/low band module design that allows for at least 3 CAs and covers the high, medium and low frequency LTE frequency ranges. The low and mid band frequencies are duplex supported by two antennas while the other two antennas support the high band. Antenna separation/isolation also allows CA to be performed between the high and mid bands and/or the low band.

Incremental steps to achieve giga data rate

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When using 4 antennas, we will first request 4x4 MIMO, but these 4 antennas need to be routed to 4 unique radio paths for each spatial stream. Simply put, a configuration with 2 dedicated antennas in the high band and 2 dedicated antennas in the mid band will not support 4 medium/high antennas. This also means that we can't simply rely on antenna isolation to multiplex mid-range and high-band frequencies, at least without reducing the antenna.

If we follow the plan for 2 CCs supporting 4x4 MIMO, then we should look at whether there are 8 spatial streams in the mid-high band. We need a way to separate the various bands on all four antennas - fundamentally, we need a way to reuse the mid-high band. We can assemble the incremental architecture by adding mid/high duplexing to the mid-band antenna and the high-band antenna.

But adding a fixed multiplexer to an existing lineup is not always easy. Demultiplexers that separate the mid-range and high-band frequencies are typically very lossy, which reduces the Rx sensitivity and leads to an increase in the Tx power demand of the power amplifier. It also has an impact on current consumption and the durability of the PA + filter.

Another option is to include components with multiple mid/high multiplexers (such as six or seven) to support all band combinations, but this approach can be costly and compared to validated designs. Great deviation.

Qorvo implements 1 Gbps method: switch multiplexer

So what is the simple step for Qorvo RFFE to achieve 1 Gbps? Flexible mid/high duplex, using switch multiplexers such as the Qorvo QM17001.

With the QM17001, a 1 Gbps front end can be implemented in three configurations without adding too much space and having little impact on currently mature components. These three configurations are:

1

Low loss bypass. To reduce the impact when not using 4x4 MIMO

2

Medium/high duplex path 1. Standard medium/high duplex, covering most bands

3

Medium/high duplex path 2. Enable mid-range or high-band in difficult conditions for multiplexing B30/B40

The radio supports the following modes using the above configuration:

1

Single band LTE (Configuration 1). Low insertion loss bypassing means little impact on current architectural specifications.

2

DL CA (Configuration 1). Medium/high duplex without MIMO can still be supported by antenna isolation.

3

4x4 MIMO, single band (configuration 1, 2 or 3). For high bands, the QM17001 can be enabled on the mid-band path to create routes for other receivers. A similar configuration can be performed for the mid-band using the QM17001 on the high-band path. The main Tx path is still in bypass mode, so the impact is small.

4

4x4 MIMO, medium/high duplex (1 Gbps) (configuration 2 or 3). The QM17001 is fully enabled and the mid/high diplexer introduces losses.

In summary, you can implement 1 Gbps RFFE by incrementally changing existing architectures, and Qorvo will help you achieve this.