In conjunction with National Youth Day, the Ministry of Youth & Sport organized the "One Million Youth Gathering Putrajaya 2011" on May 27-29 in Malaysia to encourage various beneficial activities and to promote unity among youth in the nation.


The "One Million Youth Gathering" was held in open areas with many attendees including government officials, media and visitors. Therefore they foresaw the demand on wireless broadband access would be substantial. In view of this, the event organizer appointed DG Kom, the leading system integrator in Malaysia, to build the wireless broadband network in the area using the Altai A8 series Super WiFi Base Station to provide free internet access to all visitors.


The organizer had tested many types of equipment from different WiFi vendors without success until they tried Altai's Super WiFi solution. Owing to the large area coverage (around 3 square kilometers) and high user capacity, DG Kom installed 19xA8 series base stations around the venue. The event was a great success with hundreds of thousands of youth participating in over 200 activities during the 3 day celebration.

Altai's participation at the IT Expo West in the US and Futurecom in Brazil was a great success. Altai highlighted its newly-launched U1 Super WiFi USB Client and a full series of Super WiFi products as well as the end-to-end bundled solutions at the shows. The visitors showed strong interest in the Altai U1 due to its portable design and extraordinary performance. Besides, many of them thought the Altai end-to-end bundled solution was very positive as it enables the service providers to deploy their wireless networks rapidly and generate immediate revenue.


Altai will continue its effort in promoting the latest Super WiFi technology to industry players and potential partners all over the world via different communication mediums.

Altai is going to showcase its advanced wireless technologies and the latest Super WiFi products at GITEX in Dubai, please come and visit us!


GITEX 2011
Date: Oct 9-13, 2011
Venue: Booth#A6-23&25
Dubai International Convention & Exhibition Center
Dubai, UAE

Altai Technologies unveiled its low cost, pocket size and high performance Altai U1 Super WiFi USB Client, the latest addition to its Super WiFi solution. The Altai U1 is 802.11n capable and is designed as an essential component in the Altai Super WiFi system to extend outdoor WiFi coverage to indoor areas for broadband connectivity.


The Altai U1 employs patented smart signal processing algorithms and antenna design to increase WiFi signal strength as well as the client's throughput in areas covered by the A8 series Super WiFi Base Station or A2 series Super WiFi Access Point. With powerful built-in antennas, the Altai U1 can be used to improve the link budget as much as 15 dB.


Key features of the Altai U1 include:


- Increase signal strength for both non-line-of-sight and line-of-sight coverage areas by A8 series Super WiFi Base Station, it achieves a line-of-sight range of up to 4km
- Modern and compact design provides increased mobility for the end-user, allowing the user to reach the wireless signal anywhere from the indoor area
- Simply plug & play and it can be powered from a laptop using a USB connection


The U1 is specifically designed for service operators to provide high performance wireless broadband services at an affordable price.

To provide omni WiFi coverage for large area coverage, 3 x A8-Ei are usually installed at the same site, with each A8-Ei providing coverage for 120 degrees. In this article, we are going to explore ways to optimize the performance of the co-located A8-Ei.



To optimize the co-location performance, we have to ensure that each A8-Ei pair has enough isolation between them. Firstly, we use the channel scanning to find out the RSSI of the other co-located A8-Ei.

 
To ensure optimal performance, RSSI of other co-located A8-Ei should be less than or equal to 55.

Follow the tips below to achieve the above RSSI value:

• Install A8-Ei with vertical or horizontal separation Generally speaking, vertical separation provides better isolation than horizontal separation, and vertical + horizontal separation provides the best isolation.
• Increase physical separation. The larger the physical separation, the better the isolation is. 1m vertical + 1m horizontal separation, or 3m horizontal separation is recommended as a minimum.
• Increase channel separation. The larger the channel separation, the better the isolation. For 2 x A8-Ei co-location, use channels 1 and 11 or 1 and 13. For 3 x A8-Ei co-location, use channels 1, 6, and 11 or 1, 7, and 13. Avoid using the same channel at all cost.
• Reduce TX power. The lower the TX power, the better the isolation. 21dBm or lower TX power is recommended.

In determining whether a WiFi base station is suitable to co-locate with 3G base station, there are two factors that must be considered. They are spurious emissions and interference mitigation. The spurious emissions represent how much interference a WiFi base station introduces to nearby cellular (2G/3G/4G) base stations. The interference mitigation capability represents how good a WiFi base station mitigates the interference from the nearby cellular base stations.

The carrier-grade Altai A8 Super WiFi base station is designed to very high standards in these two areas. The spurious emission levels of the A8 is designed to meet and exceed 3GPP's requirements, it meets -100 dBm / 100 KHz in GSM, TD-SCDMA (F, A) and TD-LTE (D) spectrums and meets -90 dBm /100 KHz in TD-SCDMA (E) spectrum. The interference mitigation level of the A8 is greater than +10 dBm CW for most frequency bands. Smart antenna technologies are used to combat with in-band interferences.

In this paper, we show that an A8 can be co-located with a GSM or 3G base station at a minimum antenna separation of only 0.2 or 0.5 m respectively! This is feasibly short enough for any practical deployments. Comparatively speaking, other AP may require an antenna separation of 15 to 60 m, which may not be available for many site co-location scenarios.

Spurious Emissions

The following table compares the A8 spurious emission standards against 3GPP spurious emission requirements for co-existence with systems operating in other frequency bands and co-location with another BS.

1. The co-existence spurious requirements are referenced from 3GPP for co-existence with systems operating in other frequency bands, and also referenced from a typical WLAN operator in China.
2. The co-location requirements are referenced from 3GPP for wide area BS co-located with another BS.
3. 30 dB coupling loss assumed.
4. For local BS, not wide area BS.

Minimum Antenna Separation

We use an example of an A8 co-locating with a GSM 1800 base station to see what minimum antenna separation is required. The maximum acceptable interference level at a BS receiver is

The minimum antenna separation can be calculated using the isolation loss formula below.

    or    

Substituting the A8's spurious emission design standards of -100 dBm into the above formula, the minimum antenna separation between an A8 and a GSM 1800 base station can be as close as 0.2 m, assuming antennas are side-by-side facing the same direction and 0 dBi gain at +/-90° direction. Such a close distance will be available for most of the rooftop co-location scenarios.

However, the result will be completely different if the spurious emission levels design is different, as seen from the calculation below. Using an AP that designed up to 3GPP co-existence standard of -61 dBm as an example, we arrive at a minimum antenna separation R = 60 m! This separation requirement is most likely not available for most the deployment scenarios.

The minimum antenna separations for various AP spurious emission standards co-located with GSM 1800 base station is compared in the figure below.


Interference Mitigation Level

The A8 Super WiFi base station is designed from the outset to be located outdoor among other high power radio systems, such as GSM, CDMA, 3G and PHS etc. It has multiple high quality RF filters on each receive and transmit path. It has been extensively tested and proven to work efficiently in high interference and dense-urban areas, with different kinds of cellular systems operating nearby, even within a few meters. The A8 is able to co-locate with PHS systems, 3G, GSM and CDMA systems without having any degradation in performance.

The A8 is designed with high interference mitigation requirement. Under the test condition where all desired signals are higher than the receive sensitivity by 6 dB and the interfering power is adjusted to a level such that the PER is > 8%, the interference mitigation specifications are as follows.