Skip to main content

Uplink matters! 5G-Advanced holds the answer

Uplink matters! 5G-Advanced holds the answer

The way we use our mobile devices is dramatically changing. We are already livestreaming content, creating high bit-rate videos and regularly participating in video conferencing. We will soon be entering the era of XR services, and as the Internet of Things (IoT) becomes more pervasive, it exchange data in real time. This means that many devices will be uploading data far more than downloading – reversing a historic trend.

Within 3GPP, multiple innovative solutions have been specified in previous 5G releases to cope with the need for an ever-increasing uplink. UL Carrier aggregation (CA) and EUTRA-NR Dual Connection (EN-DC) were some of the most notable enhancements which were specified to boost the uplink significantly. And as a result, Nokia has shown recently world-record 5G uplink speeds with Elisa and TPG Telecom

But there are still some uplink challenges. Two of the most notable remaining issues are limited uplink capacity at the cell edge and limited capacity for specific 5G segments: Fixed Wireless Access (FWA) customers and industrial IoT devices. The arrival of 5G FWA has given communication service providers (CSPs) a viable way of delivering high-speed broadband to customers and small and medium enterprises (SMEs) in both rural and urban environments where it is too costly or time consuming to draw fiber. However, multiple users in a single location that are gaming, working or running other data-intensive applications could create a bottleneck in the uplink. In the industrial space, growth of devices like surveillance cameras, XR glasses and robots is driving higher demand for upload. 

According to a Nokia and TechInsights 5G-Advanced research study, CSPs indicate that performance and throughput tops their list of factors triggering 5G-Advanced deployments. Nokia has been a major contributor to the specification of Release 18 that will solve outstanding uplink challenges. With improved uplink, 5G-Advanced will evolve the 5G system to its fullest potential.

But how will it be done?

The two most important factors for improving uplink are coverage and MIMO enhancements for FWA. In this blog we will explain how each will facilitate this shift.

Improving uplink coverage

5G-Advanced will extend the reach of the network for better coverage, which is often limited by uplink direction especially in time division duplexing (TDD) configurations that generally prioritize downlink over uplink. Improved uplink coverage will facilitate seamless user experience in challenging cell-edge conditions and for services requiring higher uplink data rates like FWA.

Different techniques will be used by 5G-Advanced to improve uplink coverage. First, 5G-Advanced will improve uplink coverage with the initial connection setup by using better random-access-channel coverage. This is achieved by enabling multiple transmissions for the first signal the device transmits when it is switched on. Next, 5G-Advanced will optimize the uplink data rate within the given link budget by dynamically changing the uplink waveform. The network will prioritize coverage-enhancing waveforms dynamically when the user is close to the cell edge and deprioritize them as the user moves toward the cell center. 

5G-Advanced is also expected to improve the device’s power efficiency in the scenario of coverage-enhancing waveform and Quadrature Phase Shift Keying modulation. These improvements target a reduction of the power variation of the transmitted signal. This enables operating closer to the device amplifier’s saturation point and reducing spurious emissions. Based on these factors, higher transmission power can be used for the uplink transmission while fulfilling the existing requirements defined for the transmitted signal quality.

The considered solutions allow additional power to be used by the user device while maintaining adequate reception performance at the base station. This will yield up to 1dB of link budget gain, corresponding either to a coverage gain for a given target uplink data rate or to an achievable uplink data rate increase for a given target coverage condition (e.g., the cell edge). 

New uplink enhancements will also impact non-terrestrial network (NTN) extending areas where consumers will be able to communicate.

Uplink MIMO improvements

Massive multi-input multiple-output (MIMO) systems are powering the next iterations of 5G networks. MIMO systems allow for the simultaneous transmission of multiple data streams over the same frequency, creating more capacity, reducing interference and significantly improving user experience. 

Massive MIMO techniques currently support data transmissions on both the downlink and the uplink. However, from a system coverage and capacity point of view, the uplink is the more challenging direction given how user devices have much lower transmission power and far fewer numbers of antennas compared to base stations. The overall result is a significant imbalance in system performance between the downlink and the uplink in both previous LTE networks as well as current 5G networks.  

In FWA deployments, the Customer-Premises Equipment (CPE) will have more flexible form factor constraints compared to smartphones, and as such we have standardized dedicated innovations for these deployments.

First, 5G-Advanced will support FWA CPEs that can simultaneously transmit with up to eight antennas rather than the current limit of four. Such a boost in antennas creates up to a 24 percent increase in uplink system capacity due to the improvements in range and received signal strength. 

Figure 1

Second, 5G-Advanced will support up to eight simultaneous data streams on the uplink, which will provide additional gains of up to 40 percent in the system capacity. The combination of supporting both eight transmit antennas and up to eight transmission streams will enable 5G-Advanced to provide overall system uplink performance capacity gains of up to 60 percent over current 5G networks with single user uplink MIMO transmission. This promises to significantly improve the user experience for data transfers from the user device via the FWA to the network. It also comes closer to truly matching multi-gigabit fiber in the downlink and the uplink.

Ready for more symmetrical traffic

Together uplink coverage and uplink MIMO will provide significantly higher uplink capabilities through 5G-Advanced with Release 18. Everyone will be able to enjoy a higher uplink experience with 5G-Advanced, but the biggest improvements will be felt by fixed wireless access customers that live or work near the cell edge.

For more details on 5G-Advanced, check out our Standardization page.

Esa Tiirola

About Esa Tiirola

Esa Tiirola is a Bell Labs Fellow who has worked with radio research and standardization for more than 20 years. Currently his work is focused on 5G evolution and 6G.

Fred Vook

About Fred Vook

Fred Vook is a Distinguished Member of the Technical Staff and has worked on radio research and standardization for over 30 years. Currently his work is focused on MIMO and Beamforming solutions for 5G evolution and 6G. 

Article tags