Chapter 15

1. Radio Frequency Site Survey Fundamentals Chapter 15

2. Outline • WLAN Site Survey Interview • Documentation and Reports • Vertical Market Considerations

3. WLAN Site Survey Interview • Customer Briefing • If a wireless network is being planned for your company or for a prospective client, it is highly recommended that you sit management down and give them a quick overview of 802.11wireless networking and talk with them about how and why site surveys are conducted • Just as important is a discussion about the bandwidth and throughput limitations of current 802.11a/b/g technology • A very brief explanation on how RF signals propagate and attenuate will provide management with a better understanding of why an RF site survey is needed to ensure the proper coverage and enhance performance

4. WLAN Site Survey Interview • Business Requirements • What applications will be used over the WLAN? • Who will be using the WLAN? • What types of devices will be connecting to the WLAN?

5. WLAN Site Survey Interview • Capacity and Coverage Requirements • Some preliminary design based on the capacity and coverage needs of the customer is recommended • Wi-Fi VoIP phones will need mobility and connectivity throughout the building • If you can determine that certain areas of the facility do not require coverage, you will save the customer money and yourself time when conducting the physical survey. • Depending on the layout and the materials used inside the building, some preplanning might need to be done as to what type of antennas to use in certain areas of the facility • Cell sizing and/or co-location might be necessary to properly address your capacity requirements. • In order for the wireless end user to experience acceptable performance, a ratio of average amount of users per access point must be established

6. WLAN Site Survey Interview • Capacity and Coverage Requirements • Data applications The applications that are used will have a direct impact on how many users should be communicating on average through an access point. • User density Three important questions need to be asked with regard to users. • First, how many users currently will need wireless access? • Second, how many users may need wireless access in the future? • Third, Where are the users?

7. WLAN Site Survey Interview • Capacity and Coverage Requirements • Peak on/off use • Be sure to ask what the peak times are, that is, when access to the WLAN is heaviest. • Existing transmitters • It is referring to interfering devices such as microwaves, cordless headsets, cordless phones, wireless machinery mechanisms, and so on. • However, if you don’t know that they are using 2.4 GHz cordless headsets or Bluetooth keyboard and mouse, then you may be designing a network destined for failure.

8. WLAN Site Survey Interview • Capacity and Coverage Requirements • Mobile vs. mobility • There are two types of mobility. • The first is related to being mobile and the other is true mobility. • 802.11g protection mechanism • It should be understood in advance that if there is any requirement for backward compatibility with 802.11b HR-DSSS clients, the 802.11g protection mechanism will always adversely affect throughput.

9. WLAN Site Survey Interview • Existing Wireless Network • What are the current problems with the existing WLAN? • Are there any known sources of RF interference? • Are there any known coverage dead zones? • Does prior site survey data exist? • What equipment is currently installed?

10. WLAN Site Survey Interview • Infrastructure Connectivity • Asking for a copy of the wired network topology map is highly recommended • Roaming • Is roaming required? • Wiring closets • Where are the wiring closets located? • Will the locations that are being considered for AP installation be within a 100-meter (328-foot) cable drop from the wiring closets? • Antenna structure • Hubs/switches • Will the access points be connected by CAT5 cabling to hubs or managed switches? • Are there enough switch ports? • Who will be responsible for programming the VLANs? • PoE • How will the access points be powered?

11. WLAN Site Survey Interview • Infrastructure Connectivity • Segmentation • How will the WLAN and/or users of the WLAN be segmented from the wired network? • Will the entire wireless network be on a separate IP subnet? • Will VLANs be used and is a guest VLAN necessary? • Will firewalls or VPNs be used for segmentation? • Or will the wireless be a natural extension to the wired network and follow the same wiring, numbering, and design schemes as the wired infrastructure? • Naming convention Does the customer already have a naming convention for cabling and network infrastructure equipment and will one need to be created for the WLAN? • User management Considerations regarding role-based access control (RBAC), bandwidth throttling, and load balancing should be discussed. • Infrastructure management How will the WLAN remote access points be managed? Is a central management solution a requirement? Will devices be managed using SSH2, SNMP, HTTP/HTTPS, and so on?

12. WLAN Site Survey Interview • Security Expectations • Network management should absolutely be interviewed about security expectations. • All segmentation and encryption needs should be discussed. • All authorization, authentication, and accounting (AAA) requirements must also be documented. • It should also be determined whether the customer has plans to implement a wireless intrusion detection system (WIDS) solution for protection against rogue APs and the many other types of wireless attacks. • Some security solutions, such as layer 3 VPNs, may put extra overhead on the WLAN because of the type of encryption that is used. • Overhead caused by encryption should be accounted for during the capacity planning stages. • Special considerations will have to be given to VoWiFidevices due to the latency issues that might result from EAP authentication.

13. Document and Report • Forms and Customer Documentation • Blueprints • A floor plan layout will be necessary in order to discuss coverage and capacity needs with network administration personnel. • Topography map • If an outdoor site survey is planned, a topographic map, also called a contour map, will be needed. • These contour maps display terrain information such as elevations, forest cover, and locations of streams and other bodies of water.

14. Document and Report • Forms and Customer Documentation • Network topology map • Understanding the layout of the customer’s current wired network infrastructure will speed up the site survey process and allow for better planning of the WLAN during the design phase. • Security credentials • Proper security authorization may be necessary to access facilities when conducting the site survey. • A meeting with security personal and/or the facilities manager will be necessary in order to meet all physical security requirements in advance of the survey.

15. Document and Report • Forms and Customer Documentation • Interview checklist • A detailed checklist that contains all the questions asked during the site survey interview should be created in advance. • Installation checklist • Many site survey professionals prefer to record all installation details on the floor plan documents. • An installation checklist detailing hardware placement and mounting for each individual access point is also an option. Information about AP location, antenna type, antenna orientation, mounting devices, and power sources may be logged. • Equipment checklist • For organizational purposes, a checklist of all the hardware and software tools used during the survey might also be a good idea.

16. Document and Report • Deliverables • Purpose statement The final report should begin with a WLAN purpose statement that stipulates the customer requirements and business justification for the WLAN • Spectrum analysis Identifies potential sources of interference • RF coverage analysis Defines RF cell boundaries • Hardware placement and configuration Recommends AP placement, antenna orientation, channel reuse pattern, power settings, and so on • Application analysis Includes results from application throughput testing, which is often an optional analysis report included with the final survey report

17. Document and Report • Additional Reports • Vendor recommendations • Many enterprise wireless vendors exist in the marketplace. It is a highly recommended practice to conduct the site survey using equipment from the same vendor who will supply the equipment that will later be deployed on site. • Implementation diagrams • Based upon information collected during the site survey, a final design diagram will be presented to the customer. • The implementation diagram is basically a wireless topology map that illustrates where the access points will be installed and how the wireless network will be integrated into the existing wired infrastructure. • AP placement, segmentation, and layer 3 boundaries will all be clearly defined.

18. Document and Report • Additional Reports • Bill of materials • Along with the implementation diagrams will be a detailed bill of materials (BOM) that itemizes every hardware and software component necessary for the final installation of the wireless network. • The model number and quantity of each piece of equipment will be necessary. This includes access points, bridges, wireless switches, antennas, cabling, connectors, and lightning arrestors. • Project schedule and costs • A detailed deployment schedule should be drafted that outlines all timelines, equipment costs, and labor costs. • Security solution recommendations • Based upon the site survey interviewdiscussions, the surveying company will make comprehensive wireless security recommendations. • All aspects of authentication, authorization, accounting, encryption, and segmentation should be included in the security recommendations documentation.

19. Document and Report • Additional Reports • Wireless policy recommendations • An extra addendum to the security recommendations might be corporate wireless policy recommendations. • Training recommendations • It is highly recommended that wireless administration and security training sessions be scheduled with the customer’s network personnel. • Additionally, condensed training sessions should be scheduled with all end users.

20. Vertical Market Considerations • Outdoor Surveys • Outdoor site surveys are occasionally performed for the purpose of providing outdoor wireless access for users • Calculations necessary for outdoor surveys are numerous, including the Fresnel zone, earth bulge, free space path loss, link budget, and fade margin • If outdoor access is required, ruggedized access points may need to be deployed or APs may need to be protected in weatherproof enclosures

21. Vertical Market Considerations • Aesthetics • A very important aspect of installation of wireless equipment is the “pretty factor.” • The majority of businesses prefer that all wireless hardware remain completely out of sight • Government • The key concern during government wireless site surveys is security • Obtaining the proper security credentials will most likely be a requirement before conducting the government survey

22. Vertical Market Considerations • Education • Because of the high concentration of students, user density should be accounted for during capacity and coverage planning. • In campus environments, wireless access will be required in most buildings, and very often bridging solutions will be needed between buildings across the campus.

23. Vertical Market Considerations • Healthcare • Some hospitals have a person responsible for tracking and managing all RF devices in the facility. • A thorough spectrum analysis survey using a spectrum analyzer will be extremely important • Hospitals are usually large in scale and a site survey may take many weeks. Long hallways, multiple floors, fire safety doors, reflective materials, concrete construction, and wire mesh safety glass are some of the physical conditions that will be encountered during the survey • The applications used in the medical environment should all be considered during the interview and the survey. • Wi-Fi VoIP phone deployments are commonplace in hospitals because of the communication mobility that they provide to nurses. • Because of the presence of medical patients, proper security credentials and/or an escort will often be necessary.

24. Vertical Market Considerations • Hotspots • Hotspots continue to grow in popularity and many businesses are looking to provide wireless Internet access for their customers. • Security solutions at hotspots are usually limited to a captive portal solution for user authentication to a customer database.

25. Vertical Market Considerations • Retail • The inventory storage racks and bins and the inventory itself are all potential sources of multipath problems • Wireless applications that are used in retail stores include handheld scanners used for data collection and inventory control • Coverage is usually a greater concern than capacity because wireless data collection devices require very little bandwidth

26. Vertical Market Considerations • Warehouses • Coverage, not capacity, is the main objective when designing a wireless network in a warehouse • Warehouses are filled with metal racks and all sorts of inventory that can cause reflections and multipath. • The use of directional antennas in a warehouse environment is almost a requirement. • High ceilings often cause mounting problems as well as coverage issues • Seamless roaming is also mandatory because the handheld devices will be mobile • It is also important to keep stock levels in mind during the survey.

27. Vertical Market Considerations • Manufacturing • A manufacturing environment is often similar to a warehouse environment in terms of multipath interference and coverage design • Proper protection may need to worn and ruggedized access points may have to be installed • Not to mount access points where they may be damaged by other machines

28. Vertical Market Considerations • Multitenant Buildings • Office building environments are extremely cluttered with 802.11b/g wireless networks that operate at 2.4 GHz • If at all possible, strong consideration should be given to deploying an 802.11a WLAN using the 5 GHz UNII indoor and middle bands

29. The END Chapter 15