Cell Phones Evolution: From Dyna-TAC 8000X to iphone 5

Summary:  

In this article, we highlight the development of the cellular phone from 1973 to 2012. The purpose of this article is to highlight the advancement in many elements of technology which enabled today’s smartphones.

Abstract

Neither D.H. Ring and W.R. young who articulated a true cellular radio system for mobile telephony in an internal company memorandum in bell laboratories in 1947, nor Martin Cooper who invented the first cell phone in 1973 (often called the father of the mobile phone) could have imagined the impact of the technology they envisioned on our today’s lives. Cellular communications have become an essential component of our lives. The new generations have reached a point where they cannot even imagine life without a cell phone. The mobile phone (or cell phone) transformed from being a means of voice communications only (which is what it was invented for) into a companion device that connects one person with the whole word via text messaging, internet access, and social networking. This tremendous development in cellular phone technology and in users’ demands had great impact on major engineering decisions in its development. In this article, we highlight the development of the cellular phone from 1973 to 2012. The purpose of this article is to highlight the advancement in many elements of technology which enabled today’s smartphones.

A brief history of cell phones

In December of 1947 Bell Laboratories’* D.H. Ring, with help from W.R. Young, articulated a true cellular radio system for mobile telephony in an internal company memorandum [1][2]. Young said later that all the cellular radio elements were known: a network of small geographical areas called cells, a base station transmitter in each, cell traffic controlled by a central switch, frequencies reused by different cells and so on. He stated that 1947 Bell teams had faith that the means for administering and connecting too many small cells would evolve by the time they were needed [1][3]. These concepts did not come into practice until the 1980’s when cellular phones were developed. Despite the earlier attempts by the Nordic Telephone Group (in Sweden, Denmark, and Norway) in the 1960’s and 1970’s, Motorola was the first to succeed in implementing an automated handheld cell phone [1]. Cell phones were available before in vehicles and trains but not handheld [1]. On October 17 in 1973, Motorola filed a patent for its own cellular radio system [4]. Martin Cooper, the father of mobile phone, and his team which included Motorola’s industrial design director, Rudy Krolopp, completed Motorola’s first prototype cellular phone and its base station and they called their competitors at Bell Laboratories for a demo to demonstrate in a very practical manner who had won [5]. Figure 1 shows Dr. Martin Cooper holding the 1973 prototype phone in a forum in Taiwan in 2007. That prototype was a “brick like” phone that weighed about 30 ounces (about 850.5 grams). It took 10 more years for this phone to be introduced to the market as the first commercial cell phone under the name Dyna-TAC 8000X in March of 1983. Dyna-TAC was an abbreviation for “Dynamic Adaptive Total Area Coverage.” It was 330.2 x 44.45 x 88.9 millimeters in dimensions (length x width x thickness) and weighed about 794 grams. It featured a 9-digit LED display and had memory to store 30 dialing numbers. It offered 30 minutes of talk time, eight hours of stand-by time, and took 10 hours to recharge. It was offered for about $3995. It operated on the 800MHz FM analog mobile cellular service (AMPS) technology. Figure 2 shows a photo for the Dyna-TAC 8000X. Since 1983, cell phones went through tremendous evolution from a voice calling device to a smartphone with features such as internet browsing and self-positioning using GPS technology. In the next section we quickly review this transition.

*Bell Laboratories is the research arm of the telecommunications giant AT&T

Figure 1: Dr. Martin Cooper of Motorola made the first private handheld mobile phone call on a larger prototype model in 1973. This is a reenactment in 2007. (Photo by Wikimedia Commons/Rico Shen. Photograh taken in a forum in Taipei International Convention Center)

 

Figure 2: Motorola Dyna TAC 8000X cellular Phone, known as the Cellular Brick

Evolution of Cell Phones

Since 1983, with the appearance of the first commercial cell phone, the main design trend for years was how to reduce the size, weight and price of the cell phone. In 2004, Nokia revealed the smallest cell phone ever, the 7280 shown in Figure 3. It weighed 85 grams and was as small as a lip stick, and that’s why it was also known as the lipstick phone. It had no keyboard and used a small LCD display that has 16 colors and 104 x 208 pixels resolution. It offered features such as text messaging and internet browsing via GPRS (General Packet Radio Service) technology that enabled packet communications (similar to internet protocols) on the circuit switching network of GSM. From a radio perspective, it supported four GSM bands and featured Bluetooth connectivity and FM radio. In addition, it had 50MB of internal memory (good for 1000 entries) and an integrated 0.3 MP (mega-pixel) digital camera with no zoom capabilities. The battery offered 3 hours of talk time and 240 hours of standby time [7]. It is interesting to observe the advancement in 20 years from the brick-like Dyna-TAC 8000X that supported only voice communications on a single 800MHz band and a single AMPS mode with a memory for 30 numbers only and 9 digits discrete LED display, to the 2004 Nokia 7280. After 8 years, today we have apple iphone 5, the thinnest smartphone in the world which is also shown in Figure 3. Interestingly, dimensions are bigger than Nokia 7280. Its dimensions are 123.8 x 58.6 x 7.6 mm, but weighs about 112 grams only. It supports 7 frequency bands ranging from 700MHz to 2100MHz in different modes, namely GSM (called 2G which stands for 2nd generation technology), CDMA, Wideband CDMA (W-CDMA or 3G), High-Speed Packet access (HSPA or 3.5G), and Long Term Evolution (LTE or 4G). In addition, it features WiFi and Bluetooth connectivity and GPS receiver. Regarding storage, it offers from 16GB up to 64GB Flash memory. It employs a dual-core 1.2GHz processor and 1GB RAM. It has a 4 inch LED-backlit display (10cm in diagonals) with 640 x 1136 pixels of resolution (about 326 ppi or pixels per inch). With no keypad, the user input is via the capacitive touchscreen. The integrated camera is 8MP with auto-focus and LED flash. The battery offers 8 hours of talk time and up to 225 hours of standby time. In addition to all that, the iphone, like many other smartphones, has the following sensors: Accelerometer, gyro-meter, proximity, and compass [8]. One thing to notice is: the trend is no more to reduce size only. Since for some users, the smartphone is a media hub, the screen has to be large enough. In addition, with all this functionality the battery has to be large enough. The challenge now is how thin the phone can be with all the possible integrated functionality.

Figure 3: Evolution of Cellular phones from Motorola Dyna-TAC 8000x to Apple iphone 5 passing by the smallest cell phone ever (Nokia 7280)

Technology Advances: enabling a cell phone evolution

The evolution of cell phones involved many technological advances in different domains. In the following we highlight some of these advances.

Antenna design

Antenna design transformed from the long (about 200mm) conventional monopole antenna in the Motorola Dyna-TAC to internal patch microstrip antennas implemented on printed circuit boards [9] which were first introduced by Nokia in their 8810 model that appeared in 1998. Figure 4 shows an example of such an antenna on a Nokia 8260 phone that appeared in 1999. Motorola engineers had a mindset that “Antennas do not follow Moore’s law** and they got stuck with exterior long antennas. Nokia engineers understood that antennas don’t shrink in size but they were innovative in finding a way to fold it inside the phone [10].

**Moore’s Law is an empirical law that states that number of transistors on an integrated circuit doubles every two years because the transistors shrink in size. Motorola engineers meant that antennas do not shrink

Figure 4: Example of an on-board microstrip antenna used on Nokia 8260 phone that appeared in 1999 (Courtesy of http://www.ifixit.com)Thermal design

From a mechanical design perspective, the thermal energy dissipation of the dense components that operate at relatively high power (like the power amplifier in the transmitter) required innovation in the phone thermodynamics to develop efficient and miniature cooling (or heat dissipating) techniques [11].

Battery technology

Advances in battery technology were essential to enable smaller light-weight batteries that have longer lifetime. In the 1980’s, cell phones used Nickel-Cadmium (NiCad) batteries which were very bulky and required long time to recharge. They needed special casing because of the toxic nature of Cadmium. They heated up and due to that they changed shape by time. The worst of its disadvantages is the memory effect which meant that it had to be fully used up before recharge, otherwise it remembers the last shortened charge cycle and last for less time [12]. In 1998, Nickel metal hydride (NiMH) batteries became commercial. They were thinner and lighter, got rid of the toxic cadmium, and took less time to recharge [12]. On the other hand, they still suffered from the memory effect. Lithium ion technology (introduced in 2000s) revolutionized the battery performance and enabled pocket-sized phones. They offered 30% longer talk time than NiMH batteries and got rid of the memory effect [12] [13]. Therefore it did not need a full discharge before recharging. Since 2008, Lithium Poly ion technology is widely used in smartphones because of their better capacity (40% better than NiMH of same size) [12][13]. More importantly, it doesn’t need a cell casing which makes it very light [12]. Despite the great advances in battery technology, batteries in today’s smartphones are bigger than those used in earlier cell phones. This is because smartphones offer a lot more features that require more battery capacity. Figure 5 compares Nokia8260 Li Ion battery to apple iphone 5 Li Polymer Ion battery which is thinner but quite longer. One may argue that battery technology will still work on shrinking battery size. From a physical design perspective, there may be no need for that given that the phone size is now set by the minimum display size that satisfies a smartphone user. The challenge will probably be increasing the battery capacity in mAh (milliamperes per hour) for the same size.

Figure 5: Comparison of cell phone batteries: (Left) Nokia Lithium ion BLB-2 890mAh battery used in 8260 phone (Right) Lithium Polymer ion 3.8V – 1440mAh battery used in Apple iphone 5 (Courtesy of http://www.ifixit.com)

Integrated circuit (IC) Design Technology

The electronic communications section of a cell phone has gone from almost entirely discrete implementations to a few chip solutions today. These chips include the radio transceiver (still needs some external components), the power amplifier, the baseband modem, and the application processor. This would have not happened if it were not for the great advances in the low-cost CMOS technology. The tremendous increase in transistor speeds and shrinking sizes enable multi-million transistor ICs that can perform hundreds of thousands of operations every second. Today, smartphones carry multicore processors that can handle operations as complicated and as powerful as personal computers. In fact, CMOS technology revolutionized radio design in the last decade [14] and enabled circuit architectures that led to today’s integrated on-chip solutions. One of the main advances in radio design was integrating multi-band functionality on the same transceiver chip. In the early days, phones used to operate on a single frequency band and support a single system. For example the Motorola Dyna-TAC supported only the 800MHz band for AMPS systems. In the 1990s, different mobile systems were deployed around the globe. In addition to 800MHz AMPS, North America adopted GSM (Global System for mobile Communications) and CDMA (Code Division Multiple Access) technologies both in the 800MHz and 1900MHz bands. Europe had a wide deployment of GSM already in the 900MHz and 1800MHz, and Japan used their digital PDC standard starting 1994 in the 800MHz and 1.5GHz bands [1]. Accordingly, a cell phone purchased in North America would probably not work in Europe and Middle East and vice versa. This variety of frequency bands and systems generated the need for a multi-band and multimode phone. The first multi-band phone was a quad-band GSM phone that can operate in the 4 GSM bands 800MHz (called cellular), 900MHz (called E-GSM), 1800MHz (called DCS) and 1900MHz (called PCS). Today, transceiver chips have to support 20 bands or even more in different modes (2G, 3G, and 4G) in order to cover cellular services over the globe. Figure 6 compares the printed circuit boards for the 1999 Nokia 8260 quad-band Dual-mode (2G/3G) phone and the 2012 multiband multimode iphone 5 (both sides are shown). A quick look on the two phones concludes that the number of chips on the iphone 5 is more. This is because it supports new functions such as WiFi and Bluetooth connectivity which come on a separate transceiver chip. This chip is usually a combo chip that also has FM radio and GPS receiver. The touchscreen requires a controller chip, and the same for all the sensors. Without today’s integration capabilities of CMOS technology, the iphone 5 may not be there or may has been as big as the 1983 Motorola Dyna-TAC. Another thing to notice in Figure 6 is that some chips on iphone 5 are quite bigger in size than the ones in Nokia 8260. That’s a design trend we find today: integrating more functions on a larger single chip is cheaper than having divided functionality between many smaller chips and external components. This is because board area is more expensive than on-chip area, and from IC manufacturing and testing perspective one larger chip is cheaper than many smaller chips. This tells us that in the future, we expect many of the separate controllers on the board to be integrated on single chips. Also, we expect integration of the baseband processor*** and the application processor****. Although there are still many discrete components on the iphone 5 board, they seem much less in numbers than the ones on the Nokia 8260 board. This is thanks to advances in CMOS technology that enabled new circuit architectures that avoid the use of many external components. This is also due to the advances in discrete component technology which led to the integration of many external components into modules. For example, radio transceivers require off-chip radio frequency (RF) filters for every supported band. Today, filter manufacturers can integrate many of these filters in one smaller module in order to reduce the on-board area.

***Baseband processor handles all the digital signal processing needed to extract voice and data from the received radio signals at decent quality

****The application processor is the brain of the cell phone. It translates operating system ( and software) commands to actions on the hardware. This includes processing user inputs, memory management, graphics processing,…etc

Figure 6: Revealing printed circuit boards of cell phones (Left) Nokia 8260 (Right) Apple iphone 5 (Courtesy of http://www.ifixit.com)

References

[1] Tom Farley, “Mobile telephone history, “ Online: www.privateline.com/archive/TelenorPage_022-034.pdf

[2] Roessner, D et al. The Role of NSF’s Support of Engineering in Enabling Technological Innovation: Phase II, Chapter 4: The Cell Phone. Final report to the National Science Foundation. Arlington, Virginia: SRI International, 89, 1998. citing Ring, D H, “Mobile Telephony – Wide Area Coverage,” Bell Laboratories Technical Memorandum, December 11, 1947. Online: http://www.sri.com/policy/stp/techin2/chp4.html

[3] Young, W R. Advanced Mobile Phone Service: Introduction, Background, and Objectives. Bell System Technical Journal, 7 January, 1979.

[4] Martin Cooper et al.,“Radio telephone system,”US Patent Number 3,906,166, granted September 16, 1975.

[5] Ferranti, M. Father of Cell Phone Eyes a Revolution. IDG News Service, New York Bureau, 14 (31), October 12, 1999

[6] Online Article: http://www.retrobrick.com/moto8000.html

[7] Online Reference: http://www.gsmarena.com/nokia_7280-884.php

[8] Online Reference: http://www.gsmarena.com/apple_iphone_5-4910.php

[9] G. Breed, “The Fundamentals of Patch Antenna Design and Performance,” High frequency Electronics, pp. 49-51, March 2009.

[10] Mathew Honan , “Hide the Antenna Inside the Cell Phone,”Online article: http://www.wired.com/culture/design/magazine/17-03/dp_cellphone

[11] Simons, R.E., “Application of thermoelectric cooling to electronic equipment: a review and analysis,” Sixteenth Annual IEEE Symposium on Semiconductor Thermal Measurement and Management, pp 1-9, March 2000.

[12] Nokia Nseries, “Power up! The amazing evolution of the cellphone battery,” May 25th, 2011. Online Article: http://conversations.nokia.com/2011/05/25/power-up-the-amazing-evolution-of-the-cellphone-battery/

[13] Charlie White, “From Brick to Slick: 38 Years of Cellphone Evolution [Infographic],” October 2011, Online Article: http://mashable.com/2011/10/13/cellphone-evolution-infographic/

[14] A. Abidi, “RF CMOS comes of Age,” IEEE Journal of Solid-State Circuits, vol. 39, pp. 549-561, Issue no. 4, April 2004.

Essam S. Atalla

Ph.D. Student, Department of Electrical Engineering, The University of Texas at Dallas

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