Overview of the 802.11n Standard
802.11n is the next generation of Wi-Fi technology. While the final specification is expected to be ratified in the fall of 2008, the Wi-Fi Alliance will start certifying interoperability for 802.11n Draft 2.0 standard products this summer. Draft 2.0 laptops are shipping in volume now and are expected to be software upgradeable to the standard when it is finally ratified.
The IEEE 802.11n standard was conceived with the goal of increasing wireless local area network (WLAN) data throughput to a theoretical level of 540Mbps, or 10 times the speed of 802.11g. Built on OFDM technology used in the 802.11g standard, 802.11n achieves its higher throughput, in part, by increasing channel spectrum from 20MHz to 40MHz. In addition to increasing channel utilization through MAC aggregation techniques, 802.11n also incorporates multiple antennas using a scheme called multiple-input multiple-output antenna technology, or MIMO. MIMO provides spatial diversity and spatial multiplexing for increased range and throughput, respectively.
| Description | 802.11a | 802.11b | 802.11g | 802.11n |
|---|---|---|---|---|
| Data Rate Maximum (Mbps) | 54 | 11 | 54 | 600 |
| Modulation Technique | OFDM | CCK | CCK or OFDM | Spatial OFDM |
| Frequency Band | 5GHz | 2.4GHz | 2.4GHz | 2.4 or 5GHz |
| Spatial Streams | 1 | 1 | 1 | 4 |
| Channel Width | 20MHz | 20MHz | 20MHz | 20MHz or 40MHz |
Summary of the IEEE 802.11 standard features
Considerations for Deploying an Enterprise 802.11n Network
As a leading enterprise organization, you appreciate the importance of a high-performance wireless network that can meet the ever growing needs of your users. Today’s Wi-Fi standards are pushed to the limits by enterprise-class applications such as ERP, CRM, and workgroup applications. With the transition from 802.11abg to 802.11n, however, your organization can take advantage of higher throughput, longer range, and greater reliability to finally experience true enterprise mobility.
This is not a trivial step for the industry and marks potentially the most powerful shift in the enterprise since the transition from the hub to the switch. The adoption of 802.11n encompasses not only a change in the wireless network, but quite possibly the wired network, network architecture, wirelessly enabled applications, and eventually, end user behavior.
As your organization progresses toward the vision of the all-wireless enterprise with 802.11n, consider the following:
- Capacity: Using 40MHz mode allows enterprises to get maximum predictable capacity from 802.11n, However the use of doublewide channels exacerbates the backwards compatibility that already exist with legacy 802.11a/b/g devices and reduces the number of available channels. Will your 802.11n migration strategy protect your investment in your current Wi-Fi clients?
- Scalability: An 802.11n access point (AP) provides upward of six times higher throughput than an 802.11a/b/g AP, placing significant demands on centralized wireless controllers as well as the wired switching infrastructure between these controllers and the APs. Will your network be able to handle the concentration of all 802.11n traffic without requiring upgrades to the existing wired Ethernet switching backbone?
- Deployment: While range is improved with 802.11n, predictable coverage plans are significantly harder to construct using predictive models, because the range improvement leverages multi-path, which is highly time and location sensitive, and almost impossible to predict accurately. Will your current 802.11 deployment & operations strategy be able to stand up to the test of 802.11n?