Completely Enhanced Cell Phone Keypad
Rezwana Sharmeen, Md. Abul Kalam Azad, Shabbir Ahmad, S. M. Kamruzzaman
CCompletely Enhanced Cell Phone Keypad
Md. Abul Kalam Azad, Rezwana Sharmeen, Shabbir Ahmad and S. M. Kamruzzaman Department of Computer Science & Engineering,International Islamic University Chittagong, Chittagong, Bangladesh. Department of Computer Science & Engineering, Manarat International University,Dhaka, Bangladesh. Email: {azadarif, r_sharmin_79, bappi_51, smk_iiuc}@yahoo.com
Abstract
The enhanced frequency based keypad is designed to speedup the typing process. This paper will show that theproposed layout will increase the typing speed and be flexible for thumb. Traditional cell phone keypad is not ascientific keypad from the frequency point of view.Approaches have been explored to speed up the typingprocess. We found that no manufacturer has considered thefrequency of the alphabet. The current architecture does notprovide flexibility although the users are accustomed to thecurrently available multitapping keypad. Since the currentlyavailable keypad layouts are not best suited for users, thispaper will suggest a keypad for cell phone and othercellular device based on the frequency of the alphabet inEnglish language and also with the view of structure ofhuman finger movements to provide a flexible and fast cellphone keypad. It also takes into consideration the keyjamming problem that was available in typewriter. At firstwe identified those keys of cell phone, which are easilyreachable and create less pressure on the thumb. Thus the key frequency order is calculated from anatomical point ofview. In our proposed layout we arranged the alphabet inthe frequent keys based on the frequency of the alphabet.
Key words
Cell phone, Unitap, Multitap, keypad.
1. Introduction
WAP, chatting and messaging are considered to be thedriving force of the next generation of mobile devices.New compact and extended function oriented cell phones from leading manufacturers are providing full pocketcommunication functionality. These cell phones allow users to browse the Internet, send and receive email,chatting and SMS, and handle personal data and information. All these services are closely related to textinput or typing. However, one of the most importantissues that could slow down or even prevent such devicesfrom being widely used is the awkward user interface fortext input. When SMS has become popular the 12-buttonalphanumeric keypad with traditional arrangement ofalphanumeric characters was considered to be a majordrawback. Many companies explored differentapproaches to solve this problem. We are proposing an approach to increase the typing speed thereby presentinga new mobile keypad layout taking into consideration theimportance of mobile functionality in current world and making it more flexible to the users.With the increase in the usability of cell phone, themanufacturers have designed different types of keypadlayouts. Currently there are mainly two types of keypadlayout one is Unitap and the other is Multitap. Unitaprequires single tapping of a key for any character eithernumeric or alphabetic [4]. Manufacturers (Delta II,Blackberry) have designed micro sized QWERTY keypad,which is flexible for two hand operation [1,5]. Somecompany has developed Fastap architecture by arrangingthe numeric keys surrounded by the alphabetic keys.Multitap technology is the currently available mostfrequently used keypad layout. It requires multipletapping for each character. It arranges the characters in alphabetic order. Each key has three or four characters.This type of layout is used by the leading manufacturerslike Nokia, Samsung, Motorola, Erricson etc. Anothertype of keypad layout is designed known as MessagEase[13] based on Multitap technology but yet notimplemented.
The 1st International Conference on Information Management and Business (IMB2005) aking into account the problems and the need of thecell phone user, we provide a new keypad layout withcompletely new arrangement of the alphabet which willmake a radical change in the way text input to cell phone.
2. Proposed approach
We are proposing a new approach to speed up thetyping and thereby eliminating the problem of key jammingby providing a new keypad layout, which will be flexiblefor user thumb. We have taken into consideration theconcept of flexibility of thumb movement according tomedical science and alphabetic frequency viewpoint withpaying high consideration to jam protecting [2,3,5,6].
We calculated the frequency of the appearance ofalphabet in WAP, chatting and SMS purpose by usingfrequency-calculating algorithm. The most frequentlyused alphabet are shown in Table 1. In Table 1Percentage refers to the percentage of occurrence of eachalphabet in our sample inputs. In the below table "Alp"stands for Alphabet and "Per" stands for Percentage.
Table 1:
Frequency of the single alphabetic character
Alp Per Alp Per Alp Per e 11.90% l 4.16% p 1.82%t 9.12% d 3.53% b 1.61%o 8.43% u 3.02% v 1.15%a 7.85% m 2.74% k 0.87%i 7.52% y 2.57% j 0.36%s 6.45% c 2.35% x 0.14%n 6.85% w 2.27% q 0.09%r 5.62% f 2.13% z 0.07%h 5.29% g 2.08%
We proposed a new one-handed one fingered cellphone keypad layout. Our keypad layout is designed byarranging the most frequently used alphabet in the mostfrequently used keys. Frequent keys are those, which areflexible to the user. A key is flexible when it is reachableby the finger (thumb) without much pressurizing thephysical structure and the internal joints of the thumb. Aphysical structure of the thumb is shown in Figure 1.
Figure 1:
Physical structure of thumb joint
Figure 2:
Physical structures of thumb joints in respect of angle
There are mainly two joints in a thumb (1) interphalangeal (2) metacarpophalangeal. Basically twotypes of thumb movements are required for pressing anykey (1) Flexion (2) Extension. In case of Flexionmovement the metacarpophalengeal joint is moved to forward direction whereas in case of extensionmetacarpophalengeal joint is moved to lateral direction,which is more painful and pressure creating. According to medical science, pressure on interphalangeal jointincreases with the decrease in the joint angles. If thethumb movement pressurize the metacarpophalengealjoint to lateral direction then this movement pressurizethe thumb and there by inconvenient and also a bit painful.The extension of the thumb is more painful and pressurecreating than the decrease of angle in the interphalangealjoint [13,14,15]. Position of interphalangeal joint andmetacarpophalangeal joint is shown in the following threefigures: Figure 3, Figure 4 and Figure 5. In Figure 3 forpressing key 1 the interphalangeal joint is slightly bentand this angle of joint decreases as we proceed to presskey 5 and key 9. While pressing key 9 there is extensionof metacarpophalengeal to later direction.
The 1st International Conference on Information Management and Business (IMB2005) igure 3:
Pressing key 1
Figure 4:
Pressing key 5
Figure 5:
Pressing key 9
The pressure on the joints for thumb movements topress the cell phone keys are shown in Table 2. Where"IPJ" stands for Interphalangeal Joint, "MCJ" stands for Metacarpophalengeal Joint, "Flex" stands for Flexion and"Ext" stands for Extension.
Table 2:
Statistical analysis of thumb movement for each key press
Key IPJ MCJ Flex Ext
Key IPJ MCJ Flex Ext
Firstly we placed the most frequently used charactersin the frequent keys in circular order from the mostfrequent key to least, then we again arranged the keys ofnext frequency from the least frequent key to most inreversed manner. Finally it was done again from mostfrequent key to least. In this way we designed ourproposed keypad layout. The following table will showhow the alphabet are arranged:
Table 3:
Arrangement of single alphabet
Key 1 2 4 5 7 3 6 8
Forward e t o a i s n rBackward w c y m u d l hForward f g p b n k jq xzIn our proposed new keypad layout the cell phoneusers will find the frequently used alphabet arranged inthose keys, which are convenient to press and does notneed to pay much pressure on the fingers. We have usedkey number 0 for blank space, which will also beconvenient one. As the user will find out most of thefrequent alphabet in easily reachable keys, thisarrangement will speed up the typing process. In our proposed keypad layout the most inconvenient key is 9,which we have used for inserting symbols. The functionsof the key 1 of traditional keypads will be shifted to key 9.It will lessen the finger works and will decrease the extratime and pressure required to move the position of thefinger from the most frequently used key to the least frequent one. Hence these frequency based keypad will be
The 1st International Conference on Information Management and Business (IMB2005) ery much flexible to the cell phone users in comparisonto Unitap technology.Our proposed keypad layout after arranging thealphabet is shown in the following, Figure 6.
Figure 6:
The proposed frequency based keypad layout
As we know key jamming is a severe problem in anysorts of keyboard or keypad and obviously in cell phone.To figure out the degree of key jamming we calculatedthe front combination of the alphabet of each keyaccording two-alphabet combination and three-alphabetcombination. We found that the top most frequentcombination of two alphabet are shown in Table 3 wherewe found that the most frequent two-alphabetcombination is ‘am’ which has the percentage of occurrence is only 1.11% and rest others are tend to zero.That’s why it is apparent that this architecture is also keyjamming proof. In the table below, "Syl" stands forSyllable and "Per" stands for Percentage.
Table 4:
Frequency of the two character syllable
Syl Per Syl Per Syl Per am 1.11% oy 0.07% lj 0.00%op 0.78% yp 0.05% tg 0.00%iv 0.67% nj 0.03% dk 0.00%ab 0.57% rh 0.03% lq 0.00%ef 0.46% iu 0.02% kq 0.00%nl 0.33% uv 0.01% rx 0.00%ew 0.33% nq 0.01% rz 0.00%mb 0.31% sd 0.01% hz 0.00%tc 0.12% cg 0.01% hz 0.00%sk 0.11% wf 0.01% xz 0.00%
3. Experimental Result
Key jamming problem has significant impact on typing speed. A perfect arrangement of key with the aimof speeding up the typing process, can dangerouslyhamper the typing speed if the key jamming problem isnot taken into consideration. The early QWERTY keyboard is an eye opener; it had seriously taken intoconsideration the key-jamming problem, although twohands are simultaneously used. In case of cell phone wehad to take this problem of key jamming into accountseriously as only one hand and in most of the cases one finger are used. 'E' is the most frequently used alphabetand we placed it in key 1 the most frequently used key.Our next choice would have been 'T', the next frequentlyused alphabet. We placed it in key 2 rather than key 1 toprotect key jamming. We arranged the frequently usedalphabet in such a manner that the two consecutivealphabet will be low, such as 'ew' its frequency is 0.33%and the frequency of ‘ef’ is 0.46% and the frequency of‘wf’ is 0.00%. Our arrangement is ‘ewf', here the wcharacter is placed to eliminate key jamming. Hence afterpressing the alphabet of one key we have not to wait forthe cursor to set, as the next character to be pressed will not be of that same key. Rather the next character will bein the next frequent key. By using this technology wetried to eliminate the most possible key jamming andtherefore speeding up the typing process and not makingthe user to wait for the cursor to set. We have an experiment on the data "the quick brownfox jumps over the lazy dog", and have calculated thenumber of times the most frequent keys and least frequentkeys are used. This result is shown in Table 5:
Table 5:
Quality comparison
Technology Use of mostfrequentkeys Use of leastfrequentkeys
Traditionalmultitappingkeypad 10 24Proposedtechnology 18 16From the above table it is vivid that, in our proposedkeypad layout is far more optimal then the traditionalmultitap keyboards. The user’s thumb will be less pressurized as it will require the maximum use offrequent keys and the result will be significant increase inthe typing process with less error rate.We calculated the number of key pressing based onour test data. The result is shown in Table 6.
The 1st International Conference on Information Management and Business (IMB2005) able 6:
Statistical comparison of key pressing
Data Current keypad Proposed keypad148610 322780 218077228632 496586 335504The comparison of key pressing is shown in thefollowing chart.
Models in respect to data A m oun t o f key p r ess Amount of dataCurrently keypadProposed keypad
Chart 1:
Statistical comparison of key pressingFrom the above table it is vivid that the number of keypressing for the traditional Multitaping keypad is muchhigher than our proposed frequency based keypad layouts.As our keypad will require less key tapping hence it willbe less time consuming and thereby increase the typingspeed.
4. Conclusion
For speeding up the typing process the alphabeticarrangement are required to be changed to greater extent. Inour proposed keypad layout as we have identified the frequently used keys and arranged the frequently usedalphabet in those keys, it will be convenient and less pressure creating on the finger works. Although this process will require some learning time, the users will bebenefited to great extent as soon as they become extendedto it.