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Contents1. Frequency Plannings2. Normal Frequency Reuse Technology 3. Tight Frequency Reuse4. Multiple Reuse Pattern Technology 5. Concentric Cell Technology 6. Frequency Hopping
The spectrum utilization ratio can be expressed by frequency reuse density (freuse), which reveals the tightness of the frequency reuse and can be expressed by the following equation
NARFCN is the total number of the available channel numbers, NTRX is the number of TRXs configured for the cell.
Contents1. Frequency Planning2. Normal Frequency Reuse Technology 3. Tight Frequency Reuse4. Concentric Cell Technology 5. Multiple Reuse Pattern Technology 6. Frequency Hopping
Contents1. Frequency Planning2. Normal Frequency Reuse Technology 3. Tight Frequency Reuse4. Concentric Cell Technology 5. Multiple Reuse Pattern Technology 6. Frequency Hopping
1 x 3 Frequency Reuse Pattern 1 x 3 frequency reuse pattern is also called
fractional reuse. For 1 x 3 or 1 x 1 frequency reuse pattern,
the reuse distance is quite small, so the interference in the network is quite great. Therefore, to avoid frequency collision, you must use RF hopping technology and set the parameters, including MA (mobile allocation), HSN (hopping sequence number), and MAIO (mobile allocation index offset). The ratio of number of the TRXs to that of the available frequency hopping is FR LOAD (generally, it is smaller than 50%).
Example of 1 x 3 Frequency Reuse If the available bandwidth is 10MHz ,the channel numbers are 45~94
For BCCH carriers, channel numbers is 81~94, frequency reuse pattern is 4×3 For TCH carriers, channel numbers is 45~80, frequency reuse pattern is 1×3
Because FR LOAD 1 to 2, if the bandwidth is 10MHz, the maximum base station type can be configured as S7/7/7. In this case, the frequency reuse degree is 7.14
The Characteristics of the 1 x 3 The frequencies are more tightly reused, so the network capacity is great. When planning a network, only need to plan BCCH, while it’s unnecessary
to re-plan frequencies. So the efficiency for network planning is high. Wideband combiner must be used, but the cavity combiner with frequency
selectivity is inapplicable. Co-channel and neighbor channel interference increases as the frequency
reuse distance decreases. RF hopping must be used, and the channel numbers participating frequency
hopping is twice that of the number of carriers at least. In actual conditions, BCCH cannot take measures, such as RF hopping, DTX,
and power control, therefore, in order to ensure network quality, BCCH can only use the looser 4 x 3 frequency reuse pattern.
Example of 1 x 1 Frequency Reuse One cell of one base station forms a frequency reuse cluster If the available bandwidth is 6MHz ,the channel numbers are 96~124
For BCCH carriers, channel numbers is 111~124, frequency reuse pattern is 4×3 For TCH carriers, channel numbers is 96~110, frequency reuse pattern is 1×1
the maximum base station type can be configured as S4/3/3 under 1 x 1 frequency reuse pattern. In this case, the frequency reuse degree is 7.25/9.67/9.67, so the average value is 8.86.
Therefore, the maximum base station configuration under 1 x 1 frequency reuse pattern is the same as that under 1 x 3 frequency reuse space grouping pattern, so is the network capacity.
Frequency group number Channel number MAIO
A 96,97,98,99,100,101,102,103,104,105,106,107,108,109,110 0,2,4
B 96,97,98,99,100,101,102,103,104,105,106,107,108,109,110 6,8
C 96,97,98,99,100,101,102,103,104,105,106,107,108,109,110 10,12
Contents1. Frequency Planning2. Normal Frequency Reuse Technology 3. Tight Frequency Reuse4. Concentric Cell Technology 5. Multiple Reuse Pattern Technology 6. Frequency Hopping
Contents1. Frequency Planning2. Normal Frequency Reuse Technology 3. Tight Frequency Reuse4. Concentric Cell Technology 5. Multiple Reuse Pattern Technology 6. Frequency Hopping
Conception of Concentric Cell Technology In the GSM network, concentric cell technology is used to divide
the service area into two parts: overlaid and underlaid. Essentially, the concentric cell technology concerns channel
allocation and handover, but when combining this technology with various frequency planning technologies, both expand network capacity can be improved network quality.
Conception of Concentric Cell Technology Generally, 4 x 3 frequency reuse pattern is used for the
underlaid. For overlaid, the frequency reuse patterns, such as 3 x 3, 2 x 3, or 1 x 3, are used. Therefore, all carriers can be divided into two groups, one for underlaid, and the other one for overlaid.
Contents1. Frequency Planning2. Normal Frequency Reuse Technology 3. Tight Frequency Reuse4. Concentric Cell Technology 5. Multiple Reuse Pattern Technology 6. Frequency Hopping
MA is the set of available RF bands when hopping, containing at most 64 frequency carriers. The frequency being used must be those of the available frequency
MAIO (Mobile Allocation Index Offset) MAIO is used to define the initial frequency of the hopping. Be careful to configure the MAIO of same timeslot in all channels, otherwise
interference occurs. MAI (Mobile Allocation Index)
At the air interface, the frequency used on a specific burst is an element in MA set. MAI is used for indication, referring to a specific element in the MA set.