R&D Route Shift: China's WiMAX Development Unfolds
As a frontier area of wireless mobile technology, WiMAX R&D progress has drawn continuous attention, and some domestic communication companies have invested substantial resources in the formulation of the 802.16e standard. According to reporters, as 802.16e-related products are maturing, China's WiMAX R&D route has shifted from the original "revolutionary change" to a gradual evolution from 802.16e to 802.16m.
Currently, the 802.16 protocol still has numerous technical challenges to overcome, which will have a significant impact on the commercialization process of WiMAX products.
Shift in the 802.16 Pre-research Route
To date, no operator has deployed the 802.16e mobile WiMAX specification formally defined in December 2005. IEEE launched the development of the 802.16m standard this year to further enhance WiMAX performance.
According to reporters, some domestic communication companies have invested substantial resources in the pre-research of the 802.16m standard. A major communication company, one of the key participants in the WiMAX Forum, has formed multiple WiMAX R&D teams. One WiMAX pre-research group consists of twenty core technical R&D personnel. According to one of the R&D staff members, they are currently actively participating in the formulation of the 802.16m protocol framework, namely the design discussions for the physical layer and MAC layer of the wireless link.
He told reporters: "IEEE previously believed that 802.16m would be a revolutionary change to 802.16e, but after multiple research discussions, the R&D route has been changed to gradual evolution. The reason is that 802.16e-related products are currently maturing, and 802.16m should fully leverage these existing resources."
Taking Huawei as an example, its full line of WiMAX products based on 802.16e has already been launched, including RF, base stations, indoor access equipment, etc., and the WiMAX business model is also gradually maturing. "Therefore, improving performance indicators on the basis of 802.16e to form a complete 802.16m can accelerate the R&D pace. Although the 802.16m solution has not yet been finalized, its performance indicators have been basically determined," the source said.
Competing with 3G LTE
In fact, 802.16m is a new wireless standard currently under development by IEEE, with 1-2 years remaining before its official release. Its goal is to increase downlink transmission speeds to 1Gbps in "roaming" mode or high-efficiency/strong-signal mode. The standard also requires a "high mobility" mode, with transmission speeds reaching 100Mbps.
According to the draft standard, 802.16m achieves high-speed transmission through the adoption of MIMO technology. Although 802.16m is not part of WiMAX, IEEE has committed to making 802.16m compatible with WiMAX, as well as with OFDMA-based 4G standard networks. However, the uplink rate of 802.16m has not yet been determined.
The aforementioned R&D staff member told reporters: "The completed 802.16m will compete with 3G LTE in performance." In fact, LTE is still in the standardization stage, while WiMAX has already entered the commercialization stage. Of course, the possibility of some vendors integrating LTE and WiMAX when promoting their solutions cannot be ruled out.
Three Major Technical Challenges in Product R&D
In addition to the pre-research work on WiMAX-related standards, the WiMAX product line production of many domestic communication companies has reached scale. However, the biggest obstacle to WiMAX development in China at this stage is not frequency, but the maturity of 16e products.
Reporters interviewed an R&D engineer from the WiMAX base station project team of a communication company that is also a key member of the WiMAX Forum. The project team is primarily focused on scientific research on the baseband physical layer and MAC layer data downlink encoding and modulation of WiMAX base station products.
He told reporters: "The 802.16 protocol is constantly changing. Although this gives designers considerable room for development, the expectation of network-wide compatibility also creates inconvenience in system design. Currently, there are three main technical challenges in R&D: the protocol framing method, mobility performance, and networking mode."
The R&D engineer pointed out: "The data frame structure of the 802.16 protocol currently lacks a unified fixed format. While this makes implementation very flexible, it also creates inconvenience in practical applications." This means that "the interface for control messages and the packetization/transmission format are not yet clearly defined, so a fixed frame format configuration needs to be determined."
In addition, the mobility performance of current WiMAX products has not yet met requirements. WiMAX is a broadband data service that emphasizes mobility, requiring continuous calls to be maintained at vehicle speeds of up to 120 km/h. "However, at the current stage, products can achieve designed performance in fixed access scenarios but have not yet met requirements under mobile conditions," he said.
The third challenge is that "in networking mode, multi-user co-channel interference in WiMAX products is relatively severe, failing to meet the requirement of clearly distinguishing users." The project team is currently intensifying efforts to overcome these technical challenges.
The R&D engineer also told reporters: "It is expected that the WiMAX system will be further improved by the end of this year, with key technical areas requiring improvement including data framing mode, MIMO technology, STC (Space-Time Coding) technology, and HARQ (Hybrid Automatic Repeat Request) technology. Among these, MIMO and HARQ are the focus of R&D."