WLAN / Wi-Fi
IEEE 802.11 a, b, g, j, p and IEEE 802.11n
Technology Overview
WLAN is a wireless local area network technology that uses OFDM as the multiple access scheme (except 11b). Depending on the specification, the maximum communications distance ranges from a few meters up to 100 meters. WLAN communicates in the ISM bands (2.4 GHz and 5 GHz), available all over the world. WLAN is highly optimized for IP and Ethernet. Therefore, it is ideally suited for wireless Internet access.
The IEEE 802.11n standards proposals include MIMO technologies with up to four antennas and a higher bandwidth of 40 MHz for increasing throughput. In addition to higher throughput, handover capabilities are being developed to improve the quality of service (QoS). This includes media-independent handover (MIH), specified in IEEE 802.21, and unlicensed mobile access (UMA), which increases usability by providing roaming between a 3GPP cellular standard and IEEE 802.11.
The standard proposals IEEE 802.11j and 802.11p use the half clock rate as defined in IEEE 802.11. This increases robustness to achieve higher mobility, and reduces the required spectrum bandwidth to 10 MHz.
Applications
WLAN is widely deployed for computer networking in businesses and private homes. Wireless Internet access in the form of hotspots is commonly available in hotels, coffee shops, at airports and numerous other locations. An increasing number of mobile devices already provide both cellular radio access and WLAN technology. The complementary functionality to cellular systems ensures extensive penetration in the wireless market.
IEEE 802.11p is specifically defined for car to car (C2C), vehicle to vehicle (V2V) and vehicle to infrastructure communications.
Rohde & Schwarz Test Solutions
Rohde & Schwarz offers a broad range of test and measurement equipment for WLAN. Unique test instruments such as the R&S®SMU200A vector signal generator with integrated realtime fading are available. Solutions for realtime MIMO up to 4x2 and 2x4 are also supported. Optimized for speed and high data throughput, the R&S®FSV signal and spectrum analyzer offers a 40 MHz signal analysis bandwidth, which is particularly suited for the IEEE 802.11n wideband technology. The R&S®CMW500 wideband radio communication tester and R&S®CMW270 WiMAX communication tester are prepared for fast and accurate WLAN production testing.
Key Parameters
| WLAN IEEE 802.11 a/b/g/j/p | WLAN IEEE 802.11n | |
|---|---|---|
| Frequency Range |
Show / Hide
|
Show / Hide
|
| Modulation | BPSK, DQPSK, QPSK, 16QAM, 64QAM, CCK, PBCC | BPSK, QPSK, 16QAM, 64QAM |
| Multiple Access | OFDM, CSMA/CA | OFDM, CSMA/CA |
| Duplex (Uplink/Downlink) | TDD | TDD |
| Channel Bandwidth |
20 MHz (a, b, g) 10 MHz (j, p) | 20 MHz or 40 MHz |
| Number of Channels |
2.4 GHz: 14 (overlapping), 3 (non-overlapping) 5 GHz: 12 (non-overlapping) |
2.4 GHz: 14 (overlapping), 3 (non-overlapping) 5 GHz: 12 (non-overlapping) |
| Peak Data Rate | 54 Mbit/s
(a, b, g) 27 Mbit/s (j, p) | < 600 Mbit/s |
| Max. Speed | 10 km/h
> 200 km/h (p) | 10 km/h |
| Max. Distance | 100 m | 100 m |
Standardization
WLAN IEEE 802.11 a, b, g, j have already been released. For IEEE 802.11n, the proposal is defined with implementations of higher bandwidth and MIMO support. The release of IEEE 802.11n is planned for 2009. Standardization for IEEE 802.11p is in process. Interoperability tests and marketing are defined by the Wi-Fi Alliance.
