The present invention generally relates to allocating power of a pilot channel and more particularly to a method for allocating the power of a pilot channel in consideration of the difference between the loads of the first cell and the second cell.
Generally, the forward channel in CDMA system is comprised of an Overhead Channel (pilot, paging, sync) and a Traffic Channel. Among the total power of the forward channel the power of the Overhead Channel is fixed and the power of the Traffic Channel is variable by the traffic load and Power Control.
The power allocated to a pilot channel of the Overhead Channel generally corresponds to 15˜20% of the maximum power of the forward link. For example, if 20W is available for the power of the forward link, then the power located to a pilot channel is approximately 4W (which is about 20% of the total power of the forward link).
As described above, in the existing CDMA system, the power allocated to a pilot channel is fixed. Accordingly, if too much power is allocated to a pilot channel then the power for the traffic channel decreases while the capacity for the forward link also decreases. On the other hand if not enough power is allocated to a pilot channel then the forward coverage and the field for the handoff, which depend on the amplitude of the pilot channel decrease.
Furthermore, the mobile communication system is essentially a multi-cell structure. Therefore, if a load of one cell is too high and that of the other is too low, a fixed power for a pilot channel cannot be allocated to the other channel. Thus, the efficiency of CDMA system cannot be improved.
Technical Problem
It is an object of the present invention to provide a method for dynamically allocating the power of a pilot channel. The present method allocates the power of a pilot channel on the basis of the loads of one cell and the other cell. According to the present invention, if the load of the first cell is lower than the second cell, then the first cell is enlarged and a portion of the load of the second cell is transferred to the first cell. If the load of the first cell is higher than the load of the second cell, then the first cell is reduced and a portion of the load of the first cell is transferred to the second cell. In this respect, as the power of a pilot channel varies on the basis of the load of the forward traffic channel the performance in handoff and the capacity can be improved.
Technical Solution
To accomplish the above object, the method according to the present invention comprises the following steps: reporting current power of the pilot channel for each sector and total traffic power to a Base Station Controller (BSC) in a Base Station Transceiver Subsystem (BTS); referring to a Neighbor Set List for each sector of the BTS; comparing a load of a first cell with a load of a second cell based on a report of a traffic load by referring to the list; if the load of the first cell is lower than the load of the second cell enlarging the first cell and transferring a portion of the load of the second cell to the first cell; if the load of the first cell is higher than the load of the second cell, reducing the first cell and transferring a portion of the load of the first cell to the second cell; calculating new power of the pilot channel based on the traffic load; after calculating the power of the pilot channel informing the BTSs of the calculated power of the plot channel; and at the BTSs having received the calculated power, setting the calculated power as the power of their pilot channels.
It is another object of the present invention to provide an equation for allocating the power of a pilot channel. The resulting power allocated to a pilot channel is calculated using the load L1 of the first cell and the load L2 of the second cell as below:
the power allocated to a pilot channel (Ppilot)=Pp
The above object and features of the present invention will become more apparent from the following description of the preferred embodiments provided in conjunction with the accompanying drawings.
Now, the preferred embodiment of the present invention entitled “Method for Dynamicaly Allocating Power of a Pilot Channel” will be described referring to the accompanying drawings.
In
The allocated power for each sector is represented by the following equation. First, when the second cell has the M neighbor cells in the Neighbor Set List and the total traffic power of the i-th neighbor set is referred to Ti, the load of the second cell is caculated as below:
where, L2 is the load of the second cell, Tmax is the maximum value of the total traffic power, Wi is a weighing factor of i-th neighbor set, and where
Then, the total traffic power of the first cell T1 is represented as below:
Next, when using the loads of the first cell and the second cell as calculated above, the resulting power Ppilot allocated to the pilot channel is determined by the following equation:
Ppilot=Pp
where, Pp
Although the specific embodiment of the method for dynamically allocating the power of a pilot channel according to the load in the forward-traffic channel is described, the present invention has many variations without departing from the scope of the present invention. Therefore, the scope of the present invention is not to be limited to the above embodiment, and it is defined by the following claims and the equivalence thereof.
As described above, the method for dynamically allocating the power of a pilot channel according to a load in a forward-traffic channel is employed. If the load of the first cell is lower than the load of the second cell then the first cell will be enlarged and a portion of the load of the second cell will be transferred to the first cell. If the load of the second cell is lower than the load of the first cell then the first cell will be reduced and a portion of the load of the first cell will be transferred to the second cell. Therefore, the pilot power varies on the basis of the forward-traffic load so that the performance in handoff and the capacity can be improved.
Further, the dynamic allocation of the pilot power may change the cell coverage based on the traffic load and allocate the traffic load efficiently. As such, the capacity of the forward link can be improved.
In addition, by properly controlling the ratio of the pilot power, the interference, which occurs when the pilot power becomes fixed too high, can be decreased.
Number | Date | Country | Kind |
---|---|---|---|
10-2003-0067735 | Sep 2003 | KR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/KR04/02468 | 9/24/2004 | WO | 11/7/2006 |