GSM

When using close frequency reuse technique, system interference is the most important factor for frequency reuse ratio. Usually, power control and discontinuous transmission technologies are adopted to lower system interference. To prevent interference and improve system communication quality under the same interference condition, frequency hopping technology is used. Therefore, frequency hopping is a very important … Read more

Multi-layer reuse pattern is a gradual process for TCH frequency planning. In other words, the reuse is rather loose in TCH1 layer and it is quite close in the last TCH layer .The reason for this pattern is that base band hopping is used in the Multi-layer reuse pattern. When there are rather few frequency … Read more

In TCH interval grouping, the three cells of the same BTS use the same HSN while different BTS use different HSN, and different MAIO are used by carriers in the same layer of the same BTS. The HSN of BTS A is 1, the MAIO of two carriers TCH1 and TCH2 in Group 1 cell … Read more

The actual frequency planning of certain areas is usually conducted with such areas divided into segments geographically, i.e., first divide a complex network into small networks. However, there should be some frequency carriers (when the frequency is enough) reserved at the boundary of the segments or the frequency carriers should be divided. Such boundary should … Read more

Isolated reuse technology refers to 1*3 or 1*1 reuse with short reuse distance and severe interferences, radio frequency hopping technology has to be adopted. The aggregate of hopping frequencies needs to be far more larger than the number of TRX (more than twice), MA, HSN and MAIO parameter are used to avoid frequency conflict. Let’s … Read more

GSM Underlaid Overlaid Frequency Allocation and Configuration Underlaid Overlaid  Frequency Allocation In the Overlaid/Underlaid technology, all frequency carriers in the cell are divided into two parts, of which the TRX power of some frequency carriers is lowered, then two Overlaid/Underlaid with different coverage appear, as shown in the below figure. The frequency carriers used by … Read more

Capacity increase when reuse density is multiplied: Supposing there are 300 cells Bandwidth: 8 MHz (40 frequency) Normal 4*3 reuse: reuse density=12 Network capacity = 40/12 * 300 = 1000 TRX Multiple reuse: “0” BCCH layer: re-use =14,  (14 frq.) “+” Normal TCH layer: re-use =10, (20 frq.) ” ^-“ Aggressive TCH layer: re-use = … Read more

Multi-layer reuse pattern technology means to divide the whole frequency resources into different subgroups according to specific principles. Each subgroup allocates frequency carriers to every cell by means of different reuse models, so the reuse density of each frequency carrier as well as the interference will be different in each cell. The frequency carrier with … Read more

The basic frequency reuse mode of GSM is 4*3 frequency reuse. It is the basic of other frequency reuse modes, we also call it regular frequency reuse model. “4” represents 4 sites, “3” represents 3 cells in each site. Totally 12 cells become a basic frequency reuse cluster. Different cells in the same cluster have … Read more

Requirement for Interference and Carrier to Interference Ratio in GSM GSM is an interference restricted system. Carrier-to-interference ratio (C/I), also called interference protection ratio, refers to the ratio of all useful signals to all useless signals. In GSM system, this ratio is relevant to the instantaneous location and time of MS due to irregular landform, … Read more