Defining a Wireless Solution
5.4 Moving from Requirements to Design
With solution requirements in hand, you are ready to start your wireless architecture design. In keeping with the book's "Just Enough" concept, the steps described in this section will help you select the components for an initial high-level design. This design should be sufficient to roughly scope the project and provide a starting point for further research and more detailed discussions with your technical architects and consulting partners. The final, more detailed architecture and design can be a significant project and must be performed by the team that will be charged with its implementation.
The remaining chapters and appendices within this book provide a wealth of information to assist in solution selection. Figure 5.10 shows the relationship of the book's chapters to the layers and components of the Wireless Decision Process. Additional, up-to-date information can be found on the book's web site, www.just-enoughwireless.com, and the other web sites listed throughout.
The Wireless Decision Process with Chapter References
Use the following steps to guide your selections for each of the four wireless architecture component categories. Once choices have been made in these categories, the same process can be used to support an initial design for the Implementation and Support Infrastructure component.
- Review the Technical Requirements Make sure you have a good understanding of the technical requirements for the component category that you are selecting. If you have used the forms provided in Appendix A, these requirements will be organized by the same parameters used in the descriptive chapter.
- Gain an Overview of Component Features and Selection Considerations Each component chapter contains a wealth of information; however, many details may be outside your areas of interest. To focus your efforts, concentrate on the chapter introduction, considerations, and features and function sections.
- Identify the Options Best Suited for Your Situation Using the constraints imposed by your technical requirements, you should be able to identify quickly a narrower range of options. For example, if your desired level of wireless coverage is confined to an office environment, you can focus on short- or medium-range, "Do It Yourself" networks.
- Read the More Detailed Descriptions on Your Candidate Options Refer to chapter comparison tables and read the detailed descriptions on the remaining options. This information should further refine your options and may identify the specific one that best suits your needs. Note any issues or constraints that may conflict with choices made in other architectural categories.
- Perform High-Level Research When a preferred option or set of options has been identified, perform some additional research to ensure you have the latest available information to guide your decisions. Wireless technology is evolving so quickly that getting current information is essential. Identify the vendors offering the desired solution. Visit industry and vendor web sites, read analyst reports, and contact peer organizations. Check for newly announced standards, evolving features and functions, current pricing, and new, competing options. Again, note any issues or constraints that may cause conflicts.
- Finalize High-Level Selection The information from the previous steps should be sufficient to select the candidates for your initial, high-level design and provide cost estimates for cost justification efforts.
- Conduct Detailed Research For many wireless solutions more research will be required to support the detailed design and final selection of the components to be implemented. This research can include product and vendor evaluations, technical feasibility pilot projects, and visits to corporate users of the desired technology.
5.5 Working Around Wireless Constraints
As you translate your business requirements into technical specifications, you will undoubtedly discover that the wireless environment is rife with constraints, incompatibilities, and compromises. You may discover that your original solution cannot be deployed as envisioned as limitations in areas such as wireless network bandwidth and device displays reintroduce constraints that have long been eliminated in the world of wired workstations. Don't let these issues push you into abandoning or unnecessarily delaying your foray into wireless technology. Although wireless technology has yet to reach the levels of maturity, standardization, and support found in other information technologies, corporations such as FedEx and UPS have used wireless solutions productively for years. Current wireless capabilities are sufficient to handle many practical applications, and wireless constraints can often be overcome through creative design. There are two principle categories of wireless constraints.
- Evolving Constraints Some wireless constraints are temporary. Over time, the rapid evolution of wireless capabilities will reduce constraints in areas such as standards, bandwidth, coverage, security, and support tools. For example, the throughput of short and wide area wireless networks continues to improve, and the arrival of 2.5G and 3G networks will provide high-speed data exchange across a wide geographic area. Similarly, coverage is improving as wireless network operators continue to add infrastructure.
- Inherent Constraints Other constraints such as device size, display limitations, and data entry capabilities, result from the demand for small, portable devices and are a permanent part of the wireless landscape. A typical mobile device will never support the robust applications found on a desktop. Display size and resolution determine the volume and type of information that can be presented effectively. Keyboard size or handwriting recognition schemes direct the types of interactions possible. Memory and processing power affect the architecture of the application. Size, weight, and useful battery life affect the portability and convenience of the device. These inherent constraints must be overcome by designing around them. For example, applications can use numbered menus or forms to minimize data entry, and intelligent partitioning of functionality between the device and an application server can circumvent processing and memory constraints.
There are many possible paths to take when designing a wireless solution. If the original solution is blocked by limitations, another approach or combination of approaches may give you the capabilities you need.
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