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802.11AC常见问题解答 | Airmagnet

802.11AC常见问题解答

Question Guidance AirMagnet Solution
Should I transition to 802.11ac or does 802.11n provide sufficient coverage and performance? The key benefit of 802.11ac is user capacity increases, and with the proliferation of Wi-Fi devices, capacity upgrades are needed, especially if you have an 802.11a/b/g network.Considering the costs of an upgrade, going to 802.11ac now may make sense even if 802.11n provides the needed rates and capacity, looking out for the next 2 years.If you have an 802.11n network, consider that a 1:1 swap of AP’s to 802.11ac can increase your user capacity.Also consider that a brand new 802.11ac AP may provide performance improvements even for 802.11a/n clients, considering the latest electronics that come with it. AirMagnet Survey PRO can accurately calculate the performance delivered on your current network (signal strength, measured physical layer (PHY) data rates, iPerf throughput, etc.) and whether it meets your current and future WLAN design/application requirements.
If I must move to 802.11ac, should I do a complete “rip and replace” or a slow transition? Consider these factors:

  • Immediate expectations and needs of the users, especially with regard to user capacity (many users now have 3 WLAN devices).802.11ac will improve user capacity.
  • Client population among 802.11a/b/g/n/ac. If you have few 802.11ac clients, then a transition may make more sense.
  • If you phase in 802.11ac alongside 802.11a/n in a roaming zone, 802.11ac clients may roam from an 80MHz channel to a 20MHz channel and experience notable performance disruptions.

If upgrading from 802.11n, you may benefit from upgrading an area or floor at a time.If upgrading from 802.11a/b/g, you may benefit from upgrading an entire building at a time.Having a greenfield deployment of 802.11ac only for a newly covered area is a great way to start and learn.

AirMagnet Wi-Fi Analyzer PRO will characterize your current 802.11a/b/g/n WLAN environment in terms of client type and utilization of the network, as well as throughput performance, and help determine if a complete upgrade or a phased transition is needed.During a transition, AirMagnet Survey PRO will help optimize your 802.11ac network to ensure performance for all clients.
Will I need more 802.11ac APs as compared to 802.11n? 802.11ac will support more users per AP radio, and hence a 1:1 swap will provide an upgrade in capacity.However, many environments are seeing an exponential increase in WLAN devices.A denser WLAN environment calls for smaller cells and sometimes a dual-channel 5GHz network.You need to plan and deploy according to your client base requirements, including client density, technology type, and bit rate needs.But in many cases an increase in APs is justified. AirMagnet Survey PRO provides a single-click assessment to determine if user capacity requirements are met.It also provides specific visualizations of key performance factors like channel width, channel overlap, and MCS, to guide you in adjusting channel assignments and AP placement for maximum performance.

 

Channel selection FAQs
Question Guidance AirMagnet Solution
What channel setting should I use for my 802.11ac APs? Channel assignments are one of the most critical aspects of an 802.11ac deployment.Although the simplest method is to let APs automatically set their own channels, optimal performance can be achieved by developing a channel allocation plan and assigning channels to APs per this plan.To maximize network performance, this plan should enable use of wider channels while minimizing primary channel overlap. A pre-deployment AirMagnet survey will reveal where interference affects channel availability.A post-deployment AirMagnet survey will validate channel assignment by revealing any co-channel interference and AP coverage issues.It will also specifically indicate where primary and secondary channels overlap on wider channels.
Will I have to change my channel settings on 802.11n as I transition in 802.11ac with wider channel widths? 802.11ac is backward compatible with 802.11n and 11a, and operates in a mixed mode supporting 802.11a/n/ac clients in the 5GHz band.So your 802.11ac APs can transmit to 802.11ac clients on 80MHz channels, 802.11n clients on 20/40MHz channels, and 802.11a clients on 20MHz channels.However, falling back to 20/40MHz channels will impact performance for 802.11ac clients, so it is important to assign channels in your environment to balance performance among your specific client base. AirMagnet Survey PRO will validate your channel assignment plan and help you optimize it with graphic visualizations of where different channel widths are supported, and where channels overlap.It will also validate whether your deployment meets the ultimate requirement – user performance – with a throughput survey.
Should I use Dynamic Frequency Selection (DFS) Channels? Consider first if your client base can support DFS channels.If so, does your environment allow you to reliably keep a DFS channel?If you are near an airport, for example, this may be problematic.The best way to determine this is with spectrum analysis. AirMagnet provides the only survey solution with integrated spectrum analysis.While performing a site survey, you can detect and measure any RF signal on each channel, and determine if DFS channels are available or occupied.
What services should I offer on 2.4GHz, as 802.11ac is a 5GHz only standard?How can I separate out my network between these 2 bands? Both bands provide valuable spectrum that can be used to maximize capacity of a WLAN network.One can offer high bit rate / high QoS services like video on 5GHz and best effort services like web browsing on 2.4GHz. Another model is to reserve 2.4GHz for legacy 802.11b/g clients, and serve 802.11n/ac clients at 5GHz.Most APs will support both bands simultaneously. AirMagnet Survey PRO enables a single walk-through survey to collect all relevant data in both bands.The results will determine if coverage and performance in each band meets your design requirements.

AirMagnet Wi-Fi Analyzer PRO shows you how much the current 802.11a/b/g/n network in each band is utilized, to help you determine the best way to allocate clients and services to each band.