With the introduction of 5G, more spectrum can be utilized for different applications, such as sub-6G spectrum and high-band mmWave. Operators need to make the best use of each band to fulfil their business strategy while allowing coexistence with all technologies of legacy spectrum deployed in the network. 5G can greatly benefit from leveraging much higher frequency bands than 4G, like mmWave, but high-band mmWave is not always the fastest or most cost-efficient way to deploy 5G on a large scale. 5G will also use sub-3G bands that may be unfortunately used by 4G. Therefore, spectrum re-farming from FDD to 5G is obviously easy, but not the best option as the light load in the 5G initial stage will increase TCO. It is quite difficult to launch a 5G network with the highest ROI and an optimized TCO in the shortest time. This is a challenge posed to global operators and also the reason why dynamic spectrum sharing(DSS) becomes important. DSS enables 5G signals to share 4G lanes without introducing extra lanes, which is no doubt the best choice.
Even though there is no extra application or best user experience comparing with 4G, the first 5G launch is still attractive to operators because it means the market share of first 5G users and higher user stickiness. When 5G is widely deployed, its cost and performance are key to operators.
In the Asian market, spectrum is very limited, and the introduction of new bands such as n78 and n79 are costly. Operators expect to launch 5G based on legacy FDD spectrum with the least cost. With 4G/5G DSS, 5G can be enabled on legacy FDD spectrum without introducing additional spectrum. 5G network coverage is a common concern of European operators as it is hard for them to provide a continuous coverage at the initial stage of 5G deployment. 4G/5G DSS can bring 5G users a continuous experience based on the legacy FDD network.
Without DSS, an operator that has 20 MHz of low-band spectrum would have to split that spectrum in two. In other words, they would have to allocate 10 MHz of spectrum to FDD LTE and another 10 MHz of spectrum to 5G, even though initially there would only be a minimal number of 5G users.
With DSS, an operator doesn't have to split the spectrum or have dedicated spectrum for either FDD LTE or 5G. Instead, they can share that 20 MHz of spectrum between these two technologies. This helps operators deploy 5G in a fast and agile way. 4G and 5G can be implemented on the same spectrum as required by traffic needs in each millisecond, that is, 4G and 5G are running on the same lane with delicate scheduling algorithm to avoid hitting each other. In each millisecond, based on the understanding and analysis of 4G and 5G control channel characteristics, these control channels can be scheduled in such a smart way with minimum interference to each other, whereas 4G and 5G service channels are allocated based on frequency division method. As a result, resources required by 4G and 5G can be adjusted to adapt to an optimal performance with less spectrum waste, higher ROI and better 5G experience.
Before the 4G and 5G spectrum sharing, ZTE has observed dynamic traffic trend in field networks for many years and gained rich experience in GSM/LTE, GSM/UMTS and UMTS/LTE DSS, which gives rise to the Magic Radio solution. With the development of 5G, ZTE has further explored the spectrum sharing possibilities and rolled out Magic Radio Pro that enables spectrum sharing among GSM, UMTS, LTE, 5G and even NB-IoT. With global success in spectrum sharing among FDD modes, ZTE can offer operators a faster transition from 4G to 5G with a guaranteed coverage and an optimized TCO.
In a FDD multi-band multi-mode mode, Magic Radio Pro also addresses the issue of better LTE performance and stable GSM performance. In general, spectrum is statically allocated to GSM, UMTS and LTE, while traffic load changes dynamically. Since voice and data traffic in busy hours do not completely overlap, it is obvious that static spectrum allocation is unable to deliver on-demand allocation or make efficient use of the available spectrum in a dynamic traffic scenario. Magic Radio Pro enables dynamic spectrum sharing between GSM, UMTS and LTE, which maximizes spectrum efficiency by adapting to dynamic traffic load, and implements flexible scheduling of GSM, UMTS and LTE on the same band. Magic Radio Pro is a powerful solution for operators with multi-mode networks, as it greatly enhances spectrum utilization and ultimately improves user experience.
To date, ZTE has widely deployed its Magic Radio Pro solution in the global market with more than 40,000 sites, especially in Asian market. In Europe's market, ZTE has cooperated with operators in developing LTE/NR DSS and has reached agreement on commercial application in the near future.
Case1: Helping Operator Secure No.1 with Better User Experience
GSM and LTE are traditionally two separate systems in any given network, which now becomes an increasingly serious issue in terms of spectrum utilization and monetization when spectrum resources are becoming limited against rapidly growing data demands. When Magic Radio Pro comes into play to offer dynamic and flexible coordination between not-so-efficient GSM and data-hungry LTE, LTE can enjoy more bandwidth and attract more user without affecting GSM users. This can greatly improve user experience and enhance brand image.
In Nepal, with the Magic Radio Pro solution, the operator’s LTE bandwidth can be extended from 5 to 10 MHz using GSM real-time dynamic sharing within the 10 MHz LTE bandwidth. As a result, LTE user experience is significantly improved, and available downlink PRB resource is almost doubled in GSM low-traffic scenario. While keeping stable GSM key KPIs, the downlink throughput of LTE users is improved by 100% and the cell downlink throughput has 43% improvement. Based on the performance improvement of LTE users, Magic Radio Pro solution helps the operator strengthen market position and improve its brand image.
Case2: Reducing User Churn Rate for Better Competence
GSM traffic reduces, but a large amount of low-end GSM users are still in the network and contribute little to revenue with low ARPU. LTE users still increase while its user experience is limited due to static spectrum allocation. The contribution of revenue from data usage to total ARPU continues to increase. Therefore, it will be reasonable to transfer GSM bandwidth to LTE dynamically to maximize the spectrum ROI.
In India, GSM/LTE static sharing is used for an operator at the first stage where there are a large amount of GSM service needs. The 10 MHz LTE band is shared with GSM (8 MHz LTE plus 2 MHz GSM). In the second stage, GSM/LTE dynamic sharing is applied for better LTE user experience, where 10 MHz LTE is shared with GSM in real time. The dynamic sharing solution enables LTE to have more available PRB usage compared with static sharing. Since June 2019, even if LTE bandwidth has not been extended before and after dynamic sharing, LTE downlink PRB resource still has been increased by 4 PRBs, and LTE user downlink throughput has been improved by 15%. GSM key KPIs keep stable throughout the process. In this way, Magic Radio Pro improves LTE user experience and thus helps the operator reduce user churn rate.
Case3: Improving User Experience to Boost Brand Image
GSM still dominates voice service while LTE service keeps increasing. Compared with LTE user experience improvement, GSM user experience can be squeezed a bit based on user behavior. So determining the period when GSM bandwidth can be occupied by LTE without user complaint is a delicate and important technique for operators.
In Pakistan, through the Magic Radio Pro solution, ZTE carefully studied GSM and LTE traffic distribution based on big data analysis and defined the available time for LTE bandwidth extension or GSM bandwidth reduction. When GSM traffic was low, a small bandwidth would be occupied; then LTE could be extended to a larger bandwidth. The larger the LTE bandwidth, the better the user experience. Since September 2017, LTE bandwidth has been extended from 3 to 5 MHz in a given time. LTE users have increased by around 80% after the throughput improvement. Consequently, the operator can prolong the defined time for LTE and gain better feedback from the market to improve brand image.
ZTE's Magic Radio Pro has found favor among operators for it can not only allow smooth phase out of the legacy mode and smooth transition to the new mode, but also greatly improve user experience and protect legacy investment. As the AI technology develops, AI-based spectrum sharing solution will further boost network performance and user experience in the future scenario of 4G and 5G dynamic spectrum sharing.