Key Points of mobile broadband Product Design Based on 4G Technology

Mobile WiMAX has become the preferred technology for 4G cellular technology and can now meet the requirements of new smart phones, mobile internet devices (MID) and laptops. It can provide efficient broadband connections for data, VoIP, video streams with operational QoS, and other services to support mobile broadband demands for the present and future years.

Adding WiMAX connections to mobile products can provide broadband speeds of more than 1 Mbps for all these services, while keeping the size and battery life of 3G devices unchanged. Broadband speed is opening the market for many emerging mobile computing devices. The WiMAX subsystem encapsulated in an independent module simplifies the integration of this wireless technology.

As the construction and cost of WiMAX networks continue to decline, more and more possibilities are becoming reality. All products from automobiles to electrical appliances can benefit from WiMAX (see figure 1 ). The following WiMAX products are available: Laptop, mobile phone, netbook, UMPC, and MID. The earliest mobile WiMAX products were USB adapters and PC cards, mainly used for laptop users. In big cities and urban areas, these products work well with the first generation of WiMAX base stations. Mobile users in these areas hope to have a wider access mode than Wi-Fi hotspot bandwidth.

Figure 1: the mobile WiMAX module must contain WiMAX baseband PHY devices, MAC chips, RF devices, and power amplifiers.

Since the launch of the first-generation USB adapter and PC card products, the focus of the mobile wireless market began to shift to mobile phones and other devices smaller than laptops. Although there are no standard definitions for various mobile phones, several terms have been accepted by the industry, namely smartphones and VoIP phones. In addition to basic mobile phone functions, smartphones also support email and Internet access. With the integration of multimode functions and the increasing popularity of WiMAX networks, these mobile phones can provide users with seamless voice and data services. The other is low-cost VoIP mobile phones. Traditional voice communication is the main application of such mobile phones. WiMAX is only an optional wireless technology for WAN connection. In some cases, these mobile phones may contain some other basic functions, such as short messages and very simple data transmission. The main market for VoIP mobile phones is in emerging countries and regions where wired infrastructure is weak. Most people need voice services before they need other applications.

Netbook with 7 ~ 10 inch LCD screen, small notebook that provides mobile Internet and email access. Typical internet users use Windows or Linux operating systems and support applications similar to those on laptops, but the performance level is low. Wi-Fi and other connection technologies are now standard configurations, and WiMAX will be added to the netbook in the future. UMPC is a mini tablet developed by Microsoft and Intel ~ 8 inch touch screen. Most umpcs run Windows XP Tablet at less than $1000. UMPC is common in vertical specialized markets, such as medical and catering industries. MID is Intel's first small portable device, slightly larger than a smartphone, but smaller than a netbook or UMPC. MID is used to provide the best mobile platform. It not only supports Internet access and email access, but also supports multimedia applications. Although technically appealing, it remains to be observed whether consumers are willing to carry a third device after carrying their smartphones and laptops.

Technical Requirements

Because consumers want mobile products to provide a wide range of features, wireless phone design is becoming increasingly complex. The device must support many wireless options, such as Bluetooth for headset connection, Wi-Fi for home or hotspot connection, and 3g wan connection for mobile networks. At the same time, consumers want to achieve a longer battery life without increasing the weight or volume.

As WiMAX is the first 4G technology in the market, mobile phone manufacturers are actively adding this new feature. The product designer's Integrated WiMAX approach will help determine whether a specific device meets multiple features and prove to "indeed meet" market requirements.

Select an appropriate WiMAX Module

One of the ways to ensure that mobile products provide the maximum functionality is to leave room for wireless modules that meet market requirements. By designing devices as modules, mobile device suppliers can support a wide range of wireless technologies.

An independent module of approximately 20mm x supports all requirements of mobile WiMAX authentication and can be added to new products. This module must meet a wide range of technical requirements, including suitable shape sizes, low power consumption, support for multiple frequencies and high throughput. In addition, the module must not affect the performance of other wireless devices in mobile products.

As shown in figure 1, the mobile WiMAX module must contain a WiMAX baseband PHY device, MAC chip, RF device, and power amplifier. The main processor of mobile products is generally connected to the WiMAX module through standard interfaces such as SDIO, SPI and/or USB. Using modules can simplify the design requirements put forward by mobile product suppliers. They can ignore the implementation details of some WiMAX products and focus on the core advantages to develop the best products.

Power consumption requirements

Generally, technologies that support higher data rates consume more power consumption. Consumers like higher performance, but do not want to sacrifice battery life or increase battery weight. Therefore, in order to ensure that consumers can quickly adapt to WiMAX products, the power consumption requirement of devices must be the same as that of existing technologies, although WiMAX has a higher data rate.

To reduce power consumption, mobile WiMAX devices have two modes to save power consumption: sleep mode and idle mode. When the WiMAX device does not send or receive data, some parts of the mobile device can be closed to save power consumption.

In sleep mode, mobile devices are periodically disabled, and the closing time is defined by the base station. This mode supports base station switching because mobile devices can scan other base stations. Idle mode saves more power consumption than sleep mode because mobile devices are completely disabled.

The implementation of these two modes has a great impact on the overall power consumption. Specifically, the conversion speed and actual time sequence between modes affect power consumption. In addition to these modes, SoC designers can also take full advantage of a variety of technologies to reduce power consumption in working and sleeping/Idle modes.

Since all these technologies are interrelated and depend on the time sequence and throughput requirements of data services, it is difficult to summarize the specific power consumption levels that users can expect. You can see real performance tests when running specific applications. The average call time of 3G smartphones is 3 to 6 hours, and the average Internet access time is 5 to 6 hours. To speed up the popularization, WiMAX devices must use the same type of battery to provide similar performance.

It is not very difficult to achieve this, because if the device performs idle/sleep mode conversion speed is fast enough, a higher data rate will actually reduce the overall power consumption. By transmitting more data in a shorter period of time, the WiMAX device can run for less time in the working mode, and run for a longer time in the power-down mode, the latter consumes only a small part of the former. As long as you do not run applications that always require full throughput, the WiMAX device can work properly during the life cycle of the existing battery.

Multi-band devices

Many radio spectrum rules make licensed technologies like WiMAX very frequently available. As mobile WiMAX develops today, three different frequencies seem to be the most popular. Ideally, to support seamless global roaming, mobile WiMAX devices need to support all these frequencies. The most popular mobile WiMAX frequencies are 2.3 ~ 2.4 GHz, 2.5 ~ 2.7GHz and 3.4 ~ 3.6 GHz.

Products designed for only one of the frequencies can only work in a specific country, which is suitable for mobile phones with the lowest cost. However, for users who require free roaming, there are already high-integration wireless modules on the market. They can cover all three frequencies at a reasonable price.

Interference Problems

As more and more mobile devices integrate a variety of wireless technologies, designers must ensure that they do not interfere with each other. Bluetooth provides short-distance communication for headphones, while Wi-Fi is used to connect hotspots and home networks. Both technologies work in the GHz band and work at the same time because semiconductor vendors have provided coexistence methods to reduce interference. As mentioned above, the operating frequency of WiMAX devices generally does not overlap the 2.4-GHz band of Bluetooth and Wi-Fi devices. However, because the frequencies of all three technologies are very close and the output power of WiMAX is high, such combinations can easily cause interference.

The standard organization of wireless technology has not solved the interference problem, so this task falls into the specific implementation of developers. Since Wi-Fi and Bluetooth are mature wireless technologies, it is wise that WiMAX Semiconductor manufacturers should develop and support technologies that can prevent interference from WiMAX products. In this way, * the ability of a supplier to work with other wireless technologies will be an important factor in the selection of WiMAX chipset.

Operating System Support

A wide range of mobile devices lead to a wide range of operating systems. To support these platforms and help promote the popularization of WiMAX, semiconductor suppliers need to provide device drivers suitable for the widest range of operating systems. These drivers must be tailored to the interfaces created by each Operating System Company.

For PC, Microsoft's Windows Vista and previous generation products are the effortless choices. Linux, but it has made great progress in small devices such as netbooks. For Mobile phones, the main options include Symbina, iPhone OS, RIM Blackberry, and Windows Mobile.

These operating systems account for more than 90% of the mobile phone market. Other promising new operating systems include Google's Android and Palm Web OS. In addition to obtaining the widest range of operating system support, it is also important to carefully test or even verify the support so as to ensure that the product works on schedule.

Second generation mobile WiMAX chipset

The second generation of mobile WiMAX chipset has been released successfully after the mobile WiMAX module fully complies with the IEEE 802.16 standard and WiMAX Forum certification specifications. These modules adopt a scalable ofdma phy and work in time division multiplexing mode. They support 3.5, 5, 7, 10, and 20 MHz frequencies, it also supports multiple frequencies in the range of 2.3, 2.5, and/or GHz.

The second-generation mobile WiMAX chipset is specially optimized for smartphones and PDAs and can be configured for all module-based solutions. This chipset is mainly used for various low-power operations. Because the Baseband Chip is implemented using 65nm low-leakage technology, and the extended power supply selection technology and other low-power design strategies are realized, the chip consumes extremely low power in idle/sleep mode. This chipset contains a dedicated power management IC for system-level efficient power control.