WiFi Solutions
A8 can provide a NLOS coverage radius of 350 to 500 m across the sub-urban areas where the buildings are relatively low-raised. For dense-urban areas with high-raised buildings, the coverage is highly dependable on the building and street structure, a 250 m NLOS coverage radius along a street (i.e. 500 m span) can be used as a rule-of-thumb. For outdoor open areas such as park, A8 can provide a near LOS radius of up to 1 km or more.
The number of A8 per km2 varies with the coverage radius which depends on the environment. Figure 3 summarized the number of A8 required per km2 for various coverage radii.
In general, for an area of 1 km2 in sub-urban environment, it would require 2 to 4 A8 base stations. Proof-of-concept (POC) field trials at representative environments can be conducted to verify the actual coverage radius at different scenarios and a budgetary plan mainly based on number of base stations can be prepared.
In order to save up the backhaul and site rental costs, the A8 base stations can be interconnected via the 5 GHz backhaul, the central A8 acts as a master which can connect up to 4 A8 base stations, which act as slave. If each A8 provides an average local coverage area of 0.5 km2, then a cluster can provide a total coverage of 2.5 km2.
Backhaul Architecture
The A2 will be used for point-to-point (PTP) wireless bridge which connects an A8 to a remote wired Internet outlet. The wireless bridge can be formed by either a pair of A2s (802.11a/n possible) or by an A2 and A8’s 11a radio (only 802.11a) as shown in Figure 4 below. Two pairs of A2 can also be coupled together in back-to-back manner if the target distance is more than one A2 to A2 hop. Each A2 bridge has built-in 16 dBi flat panel antenna and supports both 802.11a and 802.11n standards. When it operates at 802.11a, it supports a throughput of up to 25 Mbps, or up to 40 Mbps at 11a Turbo mode and up to 120 Mbps when operate at 11n.
Multiple A2-A8 PTP pairs can be grouped together to form an A8 cluster as shown in Figure 5 below. In the figure below, three dedicated 802.11a paths are formed with total throughput of 3 x 20 Mbps available.
However, if smaller throughput is enough, the three dedicated A2s at the master site can be replaced by the 11a backhaul radio of A8 equipped with a 9 dBi external omni antenna, forming PTMP connection as shown in Figure 6 below.
In areas where Internet outlet is very expensive to build, several master sites can be further aggregated together using pairs of A2 to be connected to a larger wired Internet outlet. In this way, a 2-tier backhaul structure is formed. Larger aggregated throughput transmission is possible by using Turbo mode or 11n mode.
The distances between various combination of A2 and A8, using different panel or omni antennas can be seen in Figure 7 below. The actual distances may be less than these values depending on the actual environment such as LOS clearance and interference conditions.
The throughput capability of the bridge pairs will change with the distances apart. The longer the distance, the lower will be the throughput. Figure 8 below shows the distances support for various throughput requirements. These figures are for reference only, which may vary according to actual environment and conditions.
Coverage, Throughput and Capacity Enhancement
In between A8s there may exist some blind spot areas that cannot receive any signal from A8s. It is more cost effective to use smaller A2 WiFi access point or A3 smart WiFi access point to cover these blind spots. In NLOS environment, where A8 cannot be seen from the blind spot area, the A2 or A3 can be set at Repeater mode as shown in Figure 14 below. In this case, it receives signal from A8, boosts it up and repeats it to nearby areas. The signal strength can be boosted up by 4 to 12 dB depends on which device and antenna is used.
The user capacity can be increased at the same time because each A2 can support extra 64 concurrent users. A3 can be used if an even larger user capacity is required. A3 supports up to extra 768 concurrent users (300 concurrent users are used in calculation). Please note that no matter A2 or A3 is used, the total throughput drawn from A8 will be increased because the signal strength can be increased allowing them to transmit at higher data rate. However, the total access throughput from A8 will still be limited to the 802.11b/g standards of 20 to 22 Mbps.
When LOS conditions can be provided, the A2 or A3 can be set at AP mode, as shown in Figure 11. This allows direct wireless backhaul connection to A8’s 11a radio, and provide additional throughput of up to 40 Mbps (turbo mode). Access throughput will be provided by using independent 11b/g radio and thus a higher throughput and user capacity can be attained.
The coverage, throughput and capacity of A8, A3, A2 and C1 are shown in Figure 12. Appropriate equipment can be chosen according to the requirements.
Indoor Coverage
There are two methods of indoor coverage.
The first is outdoor to indoor wireless method, the outdoor is covered by A8 and the signals are extended to indoor using the Altai C1 CPE. There are a few arrangements possible as shown in Figure 13 below.
The C1 CPE will receive signal from A8 and convert to standard Ethernet outlet for desktop/laptop connection. This is the standard wireless DSL application. Fixed broadband service is offered to home users using wireless local loop method. When indoor wireless coverage is required, another C1 can be connected in back-to-back manner and the second C1 is best to set at different frequency channel to minimize the interference to the A8. The C1 CPE is outdoor weather proof and therefore can be installed at the rooftop and can be shared for a few users inside the building. Independent billing is possible with the WDS function enabled.
Outdoor to indoor coverage method is recommended to use as the first priority whenever possible. This is more cost effective and time saving especially for large area low user density situation, where laying fibers are cost prohibitive.
The coverage distances of A8 and A8-E/A8-Ei can be extended substantially with the use of C1 CPE. Figure 14 below shows the estimated distances.
The second method of indoor coverage is wired method as shown in Figure 15 below. This method is complement to the outdoor to indoor method. When discrete buildings are not covered by A8 or when wired Internet outlet is already available, or when the interior areas are large enough, then indoor wired method can be used. All the A3, A2 and C1 can be used as indoor AP. The A3 is for high throughput and user capacity and the A2 is for standard omni directional coverage. The C1 is for directional coverage, when omni coverage is required, a few sets of C1 can be used. A8 can be used for indoor coverage if there is a huge hollow area inside a building, such as shopping mall or hotel.
