Will the requested investment generate an ROI, and if so, when?

If the ROI is more than 12 months out, why are you even considering it?

How will you measure and prove the ROI?

Should they expect to see you back again in 12-18 months from now when cellular data or other Wi-Fi advancements and alternatives have arrived on the scene?

If so, what happens to this investment and how much additional funding will you be likely to request then?

Can these costs be charged back to the respective departments on a per-user basis, and if so, what additional effort is needed to make this happen?

Have the business units agreed to take on this additional cost?

Your goal should be to make your request better prepared, more complete, and more compelling than other investment cases being presented by other parts of the business.

Where to Begin
To begin preparing your case for Wi-Fi, address and rationalize your responses to the following areas of assessment.

1. Wi-Fi Versus Wired LAN
If a wired LAN does not already exist where you would like to deploy Wi-Fi, you can get a general sense of the cost benefits resulting from Wi-Fi deployment by using the rule of thumb that approximately 10 computing devices can be supported on a Wi-Fi access point versus just one device on a hardwired connection. If you assume that the approximate cost to install each cable drop is $300 per hardwired connection, you would incur a cost of $3,000 to hardwire 10 devices, as opposed to a cost of $300 to hardwire a single access point that supports 10 devices. Assuming an additional cost of approximately $1,500 for the access point including installation, this equates to a total cost of roughly $1,800 or an approximate cost savings of $1,200 per every 10 devices on the network. (Note: this is subject to how many devices a single access point can effectively support, including factors such as the density of devices within the area covered by a single access point, whether access points are deployed to provide overlapping coverage, and the like.)
In assessing the desire for Wi-Fi versus wired LAN, justify whether deployment of Wi-Fi will significantly reduce the need for additional hardwired cable runs, therefore presenting a cost benefit when compared to traditional wired deployment. If you are in a scenario where a wired LAN does not already exist, consider providing wired connectivity to servers and other compute-intensive workstations and computing devices, while using Wi-Fi to support "standard" desktop use. If you are in a scenario where a wired LAN already exists, look to provide Wi-Fi in areas where ad hoc teams form and have a need to collaborate such as in conference rooms, break rooms, cafeterias, and "war rooms" (temporary team environments created to foster close collaboration on time-sensitive projects).

2. User Adoption
Is Wi-Fi something that will be easy to use, convenient, and desirable for your end users? If the answer lies somewhere between "not sure" and "no", it is unlikely that the introduction of Wi-Fi will get a much-anticipated welcome, much less continued use going forward. If there is pent-up demand, however, the chances of wide user adoption is much greater.
In assessing the demand for Wi-Fi from the user community and subsequently the likelihood of rousing user adoption, identify the various user groups, justify how they will benefit from Wi-Fi, determine whether they have business-critical or revenue-generating functions that will be better supported by Wi-Fi, and understand if these various groups of users are generally accepting of new technologies and changes to the workplace. If you can build consensus and anticipation for Wi-Fi among the user community, your chances of a successful adoption will be increased.

3. Convergence of Wi-Fi and Cellular Data
Assuming you have a need for real-time wireless connectivity, what are the environments in which your various user groups need connectivity? If wireless connectivity is predominantly needed within the "four walls" of your business, Wi-Fi is the leading consideration. However, if wireless connectivity is predominantly needed beyond the walls of your business (i.e., for field service personnel), then cellular data services such as GPRS or 1xRTT data services provided by mobile operators should be your leading consideration. Should you have user groups with a need for both forms of wireless connectivity (i.e., Wi-Fi and cellular data), you will then need to rationalize a wireless strategy that is broader than Wi-Fi alone.

In assessing the need for Wi-Fi versus cellular data services, determine when you are better served by investing in the initial capital expense and ongoing operational expense associated with Wi-Fi versus the recurring monthly fees incurred from the use of cellular data services.

4. Convergence of Wi-Fi and Cellular Voice
Will the investment in a Voice over Wi-Fi (VoWLAN) capability drive down the usage and cost of cellular voice plans and/or will it provide additional capabilities that will have a quantifiable benefit within your business? If you have a relatively large employee population that generates and receives a significant percentage of their cellular calls within the "four walls" of your business, VoWLAN should be a consideration. This should be an even stronger consideration if you have either an existing VoIP deployment or VoIP-enabled PBXs.
In assessing the viability of VoWLAN within your business, first identify what percentage of cellular voice activity occurs within the walls of your business and then assess the cost of implementing and operating a Wi-Fi network that is capable of supporting a VoWLAN capability. You can then assess the feasibility of this investment versus "business as usual" with your existing cellular service. In making this assessment, it is important to note that VoWLAN will require a Wi-Fi infrastructure that supports fast authentication in order to support seamless roaming both between Wi-Fi access points and in the handoff between cellular and Wi-Fi networks. A VoWLAN standard, however, is not expected until later this year.

5. Alphabet Soup
It is essential to know the meanings of current Wi-Fi standards such as 802.11b, 802.11g, 802.11a, 802.11i, and the like in terms of their present and future roles within your business. It is also advisable that you have an awareness of future standards that have yet to be ratified and brought to market, such as 802.11e for quality of service (QoS) and the yet-to-be-designated standard for VoWLAN.
In assessing the alphabet soup of Wi-Fi standards, if you don't already have access to the necessary experts, you must be prepared to seek expert assistance to help you wade through the various competing standards and technologies and rationalize that which is best suited to your requirements.

6. Technology Approach
There are two prevailing considerations for technology selection. The first is whether you plan for a heterogeneous or homogeneous environment of vendor technologies. The second is whether you plan for enterprise-grade or lesser-grade technology.

Identify whether you will be opting for technology that is standards-based, thereby allowing you to "mix and match" technologies that are based on the same standards (heterogeneous approach) or if you will be relying on a single vendor's technology in order to take advantage of their advanced proprietary capabilities (homogeneous approach). Will you rely on full-featured enterprise technology that comes with all the bells and whistles that make it practical to centrally monitor and manage this equipment? Or, will you rely on fewer-featured technology that may potentially make deployment or management more difficult?

7. Security
Security continues to be the black cloud hanging over Wi-Fi. How will you convince management that, in addition to the creation and enforcement of underlying policies, you have addressed all aspects of security, including those associated with the technology, the physical security of the premises and equipment, and the tools and methods to ensure the continued security of the Wi-Fi deployments in addition to the creation and enforcement of underlying policies?

Establish guidelines for what you believe to be a reasonable level of security for your instance, how you will achieve that level of security, and the benefits and risks of the approach you are taking. In short, you must be able to dissuade concerns of undue risk to the business while demonstrating the merit of your proposal to address the holistic requirements around security, both in the initial Wi-Fi deployments and as an ongoing process. Within this assessment you must also be prepared to identify if/how you will monitor for unauthorized Wi-Fi technology (i.e., rogue access points).

8. Bluetooth
What relevance does Bluetooth have when considering the deployment of Wi-Fi? Bluetooth is a personal area network (versus a local area network) that has been largely used to date as a point-to-point interconnect method between Bluetooth-enabled devices such as cellular handsets, PDAs, and printers. You need to be able to sufficiently differentiate it from Wi-Fi.

9. WiMAX
What relevance does WiMAX (802.16) have when considering the deployment of Wi-Fi? Recognizing that WiMAX will be a backhaul solution or a so-called "last mile" technology for the foreseeable future, it will complement rather than compete with Wi-Fi.

10. Centralized Management
How do you manage your WAN and LAN environments today? Do you have centralized or distributed management? Identify how you will monitor and manage your Wi-Fi infrastructure, including what additional investments are required in tools and training or third-party services and if/how you can leverage your existing network support capabilities. Due to the need to have tighter control of your Wi-Fi deployments, it will be advisable to have a centralized Wi-Fi management capability.

11. Total Cost of Ownership
Do you have a grasp on what the total cost of ownership (TCO) is for a single Wi-Fi deployment? A national Wi-Fi rollout? A global rollout? Address all aspects of TCO, including the costs required to establish policies and procedures, a baseline architecture, technical standards, site surveys, purchasing, integration and configuration, shipping and logistics, installation, validation, site-specific installation documentation, operations procedures, site monitoring and management, support, and project management.

12. Change Management
Have you considered or perhaps already developed those policies that will be required to determine which users across your business will be allowed to use Wi-Fi? What are the minimum standards for hardware, OS, and the Wi-Fi client card? If upgrades are required, how will this be achieved and at whose expense? How will users be trained? Identify how the Wi-Fi user community will be properly equipped, prepared, and engaged in using the new Wi-Fi capabilities.

13. Basis for Your Business Case
Are you basing your business case for Wi-Fi on increasing revenue, decreasing cost, or increasing productivity? Be sure to clearly identify the basis for the investment. If you are building a business case for Wi-Fi within an office environment where the benefits are based on soft productivity increases that may not be sufficiently compelling in their own right, consider associating Wi-Fi with facilities improvement, where Wi-Fi is proposed as a means to improve the work environment.

Peace, Love, and Wi-Fi
While few will question the merits of Wi-Fi, those who authorize the funding for it will certainly feel compelled to question the ROI aspects of your business case, especially if there is any hint of soft benefits included in the justification. Your course of action will be to first recognize that you are in fact competing for a finite amount of internal funding. Then set out to make your case for Wi-Fi more compelling than requests to upgrade desktops, introduce a new operating system, or roll in a new copy machine that will alert the service organization via your Wi-Fi network when it is running low on toner.