Mobile Phone Keyboard Layout Optimization

The article deals with the mobile phone character set layout optimization. We try to find the layout which on the average minimizes the number of presses of the keys on the phone keyboard within writing a short message service (SMS). MS Access database was used for all the simulations which we programmed and STATGRAPHICS Centurion XV for statistical calculations. The experiment was devided into three phases. At first, we generated random layouts and compared them. We found among them significant differencies from our point of view. At the second part we introduced relative frequencies of all the considered alphabetic characters into the model (they were calculated from the samples) and tried to improve the best found layout. At the third part we added also single-step transition probabilities of the characters to eliminate setting of the character pairs with the highest transition probabilities on the same key. To simplify the problem, the SMS samples used within this article are Czech texts without diacritical signs just like it is usual in SMS communication in present.