Презентации / 1-2 Wireless Intro
.pdf
IEEE 802.11ax
• В Wi-Fi 6 был заложен механизм, который позволяет сократить
энергопотребление устройств и уменьшить количество конкурентов за среду передачи в каждый конкретный момент времени. Этот механизм получил название TWT (target wake time). Он
подразумевает пробуждение устройств интернета вещей по таймеру только тогда, когда требуется собрать данные. В остальное время устройство «спит» и не претендует на среду передачи.
RF related deployment
guidelines
Повторение
•Виды интерфернеции
•Проект – номатический WiFi ( с роумингом)
Survey
•Ноутбук
•WiFi свисток
•Точка (с учетом вертикальной поляризации и правильным подвесом)
Принцип чем больше, тем лучше ???
Почему?
Чем определяется размер ячейки?
Повторение
Проект
•Greenfield
•Brownfield
•Учесть – рекомендации вендора:
•рекомендованный уровень 60% для Coveredge Hole Detection
•Определить тип трафика (уровень на границе, перекрытие)
•Учесть необходимость и режим работы контроллеров
802.11n/ac Wireless Deployment Guidelines
Capacity and Performance from Wireless
Data Only Applications
•Casual wireless access (not primary access)
•Low bandwidth data applications
(email, web, file access)
•Access Point installed every 25 meter
•Always use dual radio Access Points (2.4GHz and 5GHz)
•Location accuracy will be reduced
Data and Voice
•High density wireless access (primary access)
•Simultaneous VoIP and data usage
•Access Point installed every 18 meter
•Always use dual radio Access Points (2.4GHz and 5GHz)
•Location accuracy will be increased depending on placement
Building example with few floors (capacity)
• 4 floors building
• 45m x 40m per floor
• 1800 m2 per floor or a 7200 m2 building
§Assuming 1.6 wireless devices per user soon to be the norm (voice and data) in Enterprise and SMB
•Accepted metrics for employee density in an office building is
•10 m² per employee (including all shared areas like lobby, restrooms, kitchen …) according to ILO estimates
• Calculations:
•For 7200m2, we have 720 employees
•720 employees means 1152 wireless devices
Enterprise WLAN Design — Data
Generic guidelines for only data application - Coverage
§465 m2 per AP (1 AP every 25 m)
§7200 m2 of carpeted area may require 16 APs
§10% overlap of coverage cells for roaming support
§AP at 60% power for coverage redundancy
§In case of AP failure
§Average -75dBm at the edge of each cell
§Can only be confirmed by site survey
Needs to be validated for capacity:
1152 devices on 16 APs = 72 devices per AP: too much! Max recommended value is around 50 devices per AP
Coverage vs capacity… 16 APs vs 24 APs (6 per floor) à evolution!
Число одновременных сессий
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Серия |
3600 |
3702 |
3800 |
4800 |
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Число |
50 |
200 |
400 |
480 |
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клиентов |
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Enterprise WLAN Design — Data and Voice
Generic guidelines for voice and data applications - Coverage
§270 m2 per AP (1 AP every 18 m)
§7200 m2 of carpeted area may require 26 APs
§15% overlap of coverage cells for roaming support
§AP at 60% power for coverage redundancy in case of single AP failure
§Average -67dBm at the edge of each cell
§Can only be confirmed by site survey
§Implement Cisco Centralized Key Management, 802.11r, OKC/PKC
§Reduces latency associated with roaming
§Do not implement Cisco Aggressive Load Balancing
Needs to be validated for capacity:
1152 devices on 26 APs = 44 devices per AP: better!
Enterprise WLAN Design — Multicast Video
ØGeneric guidelines for voice and data applications still apply.
ØMaximum of 20 clients per AP on regular Access Points
§Each multicast will be sent as a unicast to subscribed clients.
§Each unicast will be sent to each device at their connected data rate
§Changes dynamic of multicast being sent at lowest common denominator data rate.
§Must implement Cisco VideoStream technology.
ØConfirm that LAN can support multicast traffic loads prior to allowing application on
WLAN.
§Implement IGMP snooping to prevent LAN from being overwhelmed with
multicast traffic.
Ø20 clients per regular AP for 1152 clients means 58 APs
Ø58 APs on 4 floors means around 15 APs per floor (1 AP every 7m): unreasonable… except if you choose Cisco 3600!
ØCisco 3600 allows for 44 VideoStream clients per AP à 27 Aps
(still TBD for the 3700 AP)
VIDEO
NOT
AVAILABLE