Implementing 802.11ac – revolution or evolution?: Page 2 of 4

April 14, 2014 //By Stephane Persyn, Fluke Networks
The 802.11ac standard is due to be ratified in early 2014. This article explains what it offers and provides tips on planning implementation.
provided they are spatially separated. In theory 802.11ac can handle up to four spatial streams per client, and each device continuously receives the full bandwidth on offer (Figure 1).


Figure 1 — Multi-user MIMO.

GCMP security protocol

The security protocols used with 802.11ac will in most respects be the same as those used with 802.11n, so devices will largely use AES-CCMP. However, 802.11ac also permits use of GCMP – the Galois/Counter Mode Protocol - which reduces latency and is also computationally faster.

Phased introduction

The first wave of 802.11ac will include 80MHz channels and 3x3 APs. The next wave will bring 160 MHz channels, MIMO configurations greater than 3x3 and multi-user MIMO. Physical layer connection rates will eventually reach 6.9 GHz.
In theory, most initial implementations should enable speeds of up to 1.3 Gbps as well as better coverage than 802.11n. In practice, 802.11ac can only reach Gigabit-per-second speeds in laboratory conditions. Its range is also likely to be more limited than 2.4 GHz 802.11n and 802.11g, and it can only deliver as much broadband as the slowest link in the network. However, user throughput (in bits per second) will increase, increasing AP capacity. Table 2 shows a comparison between 802.11n and 802.11ac protocols.


Table 2 — Comparison of 802.11n and 802.11ac protocols.

Planning 802.11ac introduction

We believe most people will have a hybrid network for some time. This will require design and planning capability to cover 802.11ac and 802.11n to ensure users obtain the best performance with both.

Network engineers should also consider upgrading the capacity of their Ethernet access and uplink networks. For example, if the AP links are currently 100MB, they will need to be upgraded to 1GB; if 1GB, consider upgrading them to 2GB. Aggregation links need to be sized to allow for all the 802.11ac APs they will have to accommodate.

There are five key factors to consider when planning implementation.

1) Throughput - 802.11ac should give better

Design category: