Impact of direct release stations on Wireless Networks

We are already familiar with wireless networks, but what are the impacts of direct release stations on wireless networks? This article analyzes this issue and hopes to help you.

Blocking interference: When a receiver receives a weak and useful signal, it is blocked by saturation distortion caused by a strong out-of-band signal. The generation of blocking interference is related to the out-of-band suppression capability of the GSM receiver, the carrier transmit power of CDMA, and the filter characteristics of the receiver. Blocking interference will cause the GSM receiver to fail to work due to saturation.

1.1 ways to reduce interference

Method To reduce stray interference: A filter can be added to the transmitter of the interference system to eliminate stray interference, the transmitter filter eliminates stray levels in the signal band range of the system receiver from interference to the maximum isolation required by the system (3 ).

Methods To reduce Intermodulation Interference and blocking interference: In the CDMA system, the Intermodulation Interference and blocking interference of the repeater to the GSM network can be eliminated in the Receiver Filter of the GSM system, the Receiver Filter eliminates interference from the signal level in the frequency range of the system transmitter to the maximum isolation required by the system. The document provides several specific measures to solve Intermodulation Interference (4 ).

1.2 impact of interference on Network Services

The interference of the direct station on the network directly affects the service quality of the network. The main impact of the interference of the direct station on the network is: within the coverage area, the user's disconnection rate is high; for users with fast moving speeds, the cut-in success rate between cells is reduced; for direct playback stations, the uplink quality is poor, the switching ratio is large, and the switching frequency is high.

2. Influence on coverage radius and capacity of cells

Coverage radius of 2.1 base stations in intensive urban areas

When a direct station introduces a wireless network, it will have some impact on the coverage of the base station. Taking Guangzhou as an example, the formula available for the propagation model of an outdoor base station is as follows:

Lp indicates path loss, hm indicates the height of the mobile station antenna, heff indicates the base station antenna, K1 indicates the attenuation constant, K2 indicates the distance attenuation coefficient, and K3 and K4 indicates the height correction coefficient of the mobile station antenna; k5, K6 is the base station antenna height correction coefficient, K7 is the diffraction correction coefficient, and Kclutter is the correction coefficient determined by different features.

For intensive urban areas, the residential radius of CS and PS businesses is shown in table 1. Among them, CS (Circuit Service) includes Circuit-based voice and data services; PS is the Packet Service business, that is, the grouped data business.

When a direct station introduces a wireless network, the uplink noise of the base station is increased, which reduces the sensitivity of the base station receiver. The decrease in sensitivity will directly affect the capacity of the residential area and the coverage radius of the base station. The following uses the propagation model of an outdoor base station in Guangzhou to calculate the coverage radius of the residential area and the relative ratio of the coverage radius to the coverage radius without the direct station. As shown in table 2, dense urban areas are used as an example.

Table 2 lists the coverage radius under different △fbts-rise. The relative ratio (A) in table 2 is derived from the coverage radius of tables 1 and 2, that is, A = (R2/R1) × 100%. As can be seen from tables 1 and 2, the introduction of the direct station has a great impact on the coverage radius.

Influence of 2.2 on cell capacity

The wireless network capacity is determined by the number of base stations and base station capacity. The capacity of the base station is related to the following factors: the number of carrier frequencies, service types, and service quality.

The cell capacity is restricted by the interference caused by the transmit power of the base station, adjacent base stations, and all the mobile stations in the cell.

The introduction of the direct station increases the traffic volume, while a call with a new key increases the interference noise level. Every signal sent by the user is an interference signal for other signals, that is, each signal is drowned in the broadband interference signals produced by other transmitters. When new users no longer have enough power to overcome the interference of other mobile users, the system's upstream capacity limit is reached.

The ratio of the energy received by bits to the noise density of users directly affects the system capacity of cells. Eb/No, and the interference of neighboring areas caused by the introduction of the direct release station will also affect its ratio and the cell capacity.

3. Knot

With the promotion of 3G technology, the direct station will also play a huge role in 3G networks. It should also be noted that the direct station will still cause the above interference to 3G networks, therefore, in the process of network planning and optimization, it is of great significance to analyze the impact of the direct release station on the wireless network.