Cost 231 Hata Model        

 

First generation GSM systems operate at 900 MHz band. As the demand on the service increased, allocation of new channels to the service has been provided by assigning 1800 MHz band to the system. Hence, first system can use Hata Model for prediction since Hata Model covers frequency range of 100 to 1500 MHz. However, second system cannot. Cost 231 have addressed this problem and a new model which covers frequency range of 1500 MHz to 2000 MHz has been brought forward by Cost 231 [1].

(1)
 
            Cost 231 Hata Model can be written as follow:


 

 where a(hm) is defined as in equation (2).

 

 

(2)
 
           0 dB for medium sized city and suburban centers with moderate city centers.

Cm=

           3 dB for metropolitan centers

 

 

Restrictions of the model are as in table 1.

 

Parameters

Range of Validity

Frequency f, MHz

1500-2000

Base Station Effective Height hb, m

30-200

Mobile Antenna Height hm, m

1-10

Distance R, km

1-20

                                Table 1 Restrictions of the Cost 231 Hata Model  

           

 Application of this model is limited to cases in which base station antenna is above the rooftops of the adjacent buildings.

 

Although Modified Hata could be used in the same ranges above, use of this model is more popular as representative of Okumura’s curves in given ranges since model is very simple with respect to Modified Hata Model. A comparison of two models is given in figure 1 taken by using Wireless Simulator Program. In the figure, it is shown that Cost 231 Hata Model shows similar manner with Modified Hata Model in Urban area. They have 3 dB differences and one reason for this difference could be building percentage correction in Modified Hata Model. If used terrain had different building percentage the difference would be increasing or decreasing depending on the terrain. However, when study is done for open area and Suburban area, Modified Hata model deviates much more from Cost 231 Hata Model. All these results mean that Cost 231 Hata Model agree well with Okumura Curves in Urban Area.

Terrain Parameters:

Average Width: 73.8 m

Average Building Height: 17.49m

Percentage of Buildings: 37%
 

Study Parameters:

Frequency: 1800 MHz,

TX Height (hb)=50m

Mobile Height (hm)=1.5m

TX Gain:  13 dBi

City Size: Large

Area Type:

Modified Hata Path Loss: Open Area

Modified Hata Path Loss (1): Suburban

Modified Hata Path Loss (2): Urban

 
 
 


 

 


Figure 1 Comparison of Modified Hata and Cost Hata Model

 

            The application of the model is limited to large and small macro cells, and this model must not be used for micro cell coverage area prediction.

 

[1]  Blaustein Matha. , “Radio Propagation in Cellular Networks” ,Artech House, Boston-London,1999