Browse Prior Art Database

WLAN Device with Narrow Band Radio Subsystem for Channel Measurement Support

IP.com Disclosure Number: IPCOM000198264D
Original Publication Date: 2010-Aug-23
Included in the Prior Art Database: 2010-Aug-23
Document File: 2 page(s) / 79K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

WLAN devices provide usually means to select system parameters such as modulation and coding scheme, packet size or transmit power (WLAN: Wireless Local Area Network). With the latest development of the IEEE802.11n standard the numerous configuration options make it difficult for the user or the system integrator to find the optimum parameter setting for a given application and environment. In this case, intelligent algorithms are used to dynamically adapt the critical parameters to the current operating conditions. For some parameters, e.g. for the decision between single stream or multiple stream transmission in 802.11n, the optimum setting depends mostly on the channel characteristics. Although all WLAN chip sets can perform channel estimation for each data packet as part of the detection process, the results, i.e. the channel transfer function, is not available to entities outside the chip sets. Parameter selection schemes, which are typically part of a device driver running on a separate Central Processing Unit (CPU), can therefore not receive the correct channel information except the Received Signal Strength Indicator (RSSI). Parameter adaptation schemes such as MCS selection are usually based on the rate-fallback concept (MCS: Modulation Coding Scheme). The rate-fallback concept is a trial and error scheme where the MCS is adjusted towards higher data rates if the frequency of packet errors is low and towards lower data rates if frequent packet errors occur. The scheme is not particularly suitable for mobile applications with fast varying channels. Furthermore, in 802.11n systems the set of available MCS provides in some cases several alternatives for obtaining the same data rate, i.e. in some cases the same data rate can be achieved with a single spatial stream or with multiple spatial streams. Therefore, the fallback mechanism based on simple either up or down decisions can not be applied straightforward. Current 802.11n devices avoid the described problem by using only a subset of the available MCS in their adaptation schemes, i.e. a pre-selected adaptation scheme is used which has a reasonable performance in most applications.

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Support

Idea: Dr. Mattias Lampe, CN-Peking; Jifeng Tian, Ph.D., CN-Peking; Zhijun Li,

WLAN devices provide usually means to select system parameters such as modulation a scheme, packet size or transmit power (WLAN: Wireless Local Area Network). Wit development of the IEEE80
user or the system integrator to find the optimum parameter setting for a given applicatio environment. In this case, intelligent algorithms are used to dynamically adapt the c
to the current operating conditions.

For some parameters, e.g. for the decision between single stream or multiple str 802.11n, the optimum setting depends mostly on the channel characteristics. Altho sets can perform channel estimation for each data packet as part of the detection pr
i.e. the channel transfer function, is not available to entities outside the chip sets. Pa schemes, which are typically part of a device driver running on a separate Central Proce (CPU), can therefore not receive the correct channel information except the
Indicator (RSSI). Parameter adaptation schemes such as MCS selection are usually based o rate-fallback concept (MCS: Modulation Coding Scheme). The rate-fallback conce
scheme where the MCS is adjusted towards higher data rates if the frequency of p
and towards lower data rates if frequent packet errors occur. The scheme is not par
for mobile applications with fast varying ch
available MCS provides in some cases several alternatives for obtaining the same d
some cases the same data rate can be achieved with a single spatial stream or with streams. Therefore, the fallback mechanism based on simple either up or down deci applied straightforward. Current 802.11n devices avoid the described problem by us
of the available MCS in their adaptation schemes, i.e. a pre-selected adaptation scheme i has a reasonable performance in most applications.

A novel solution is proposed which provides a simple and cost-efficient method characteristics. These characteristics allow assessing the degree of multipath effec and Access Point (AP) as well as the time variance of the channel. The proposed s a cost-efficient narrowband radio module integrated into the WLAN device. The radi in the same freq
WLAN operation.

The narrowband radio can either share the antennas of the WLAN device through a Radi (RF) switch, a power splitter or another type of RF multiplexing. A separate antenna WLAN antenna can also be used. In Figure 1 the proposed hardware architecture depicted architecture is typical for an AP. The architecture of the client side, e.g.
for PCs or Notebooks, allows usually tasks of the CPU which are performed by However, in this case the basic architecture remains the same only that the CPU
of the WLAN device.

The CPU controls the execution of measurements. The used narrowband radio chip
internal microcontroller core. Thus, some measurement algorithms may have b
implemented on the chip. The CPU ensures that the transmissions of the narrowba
during the measurements interfere only slightly w...