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V PUTTING IT TOGETHER The Wireless Data Handbook, Fourth Edition. James F. DeRose Copyright © 1999 John Wiley & Sons, Inc. ISBNs: 0-471-31651-2 (Hardback); 0-471-22458-8 (Electronic) 259 16 DEVICE ALTERNATIVES 16.1 INTRODUCTION: COMBINATIONS AND PERMUTATIONS A bewildering array of subscriber unit options are available for wireless data ranging from fully integrated terminal/modem/radio units to multibox combinations of PCs, external modems, cellular transceivers, and portable faxes. A (too) simple representation of some of the terrestrial variations is illustrated in Figure 16-1. This convoluted collection of hardware alternatives is extraordinarily volatile. It is not uncommon for a monthly trade magazine to publish reviews of a product only to have some details revealed as outdated by the vendors new ad in the same issue. An up-to-the-minute review of the wide range of product possibilities makes little sense for a book with an even slower publishing schedule. There is also the question of personal choice in devices. For some users carrying an extra bag isnt as comfortable as putting a palmtop in their pocket. 1 Users with a similar profile require at least a notebook because they cannot tolerate the small keyboard, hard-to-read display, or Windows incompatibility 2 of some palmtops. Still others will carry the latest desktop replacement notebook PC even if it weighs 9 pounds. The key trends for pivotal segments that permit the devices to communicate wirelessly is clear: 1. Universal adoption of the PC Card, Type II format radio modems, with multiprotocol capability. These are most often seen in notebook/laptop PCs. 2. Integration of radio modems within devices, especially for custom designed, rugged terminals. However, full integration also extends to pagers as well as voice handsets. The Wireless Data Handbook, Fourth Edition. James F. DeRose Copyright © 1999 John Wiley & Sons, Inc. ISBNs: 0-471-31651-2 (Hardback); 0-471-22458-8 (Electronic) Figure 16-1 Device combinations and permutations. 260 DEVICE ALTERNATIVES 3. Relentless attempts to introduce useful, well-packaged radio modems for palm PCs. 16.2 MODEM COMPLEXITY Wireless modems have four levels of hardware sophistication: 1. No hardware consideration for errors. With data over cellular this class of modem is usually limited to very low speed (3001200 bps) where error tolerance is high. Error control rests with simple communications protocols such as Xmodem 3 (and its variants), Kermit, 4 and Zmodem. 5 These modems are virtually an extinct breed, but the overlay protocol Zmodem is still recommended by BCTEL 6 because of its ability to resume the transfer at the point of disconnect. 2. Error detection mechanisms, combined with ARQ techniques, and often accompanied by packet resizing to optimize performance. These units tend to be moderate speed (2400 bps) since longer burst errors can now be tolerated. The foremost examples are Microcom units and their many MNP cousins. These moderate-bit-rate protocols are being relegated to history, appearing only as artifacts in multiprotocol modems. 3. Trellis-coded modulation to provide initial error correction capability at higher bit rates (520 kbps). This more reliable data transmission technique is usually combined with error detection, usually V.42, and ARQ to improve the chances of successful message delivery. On cellular these modems are increasingly equipped with signal shaping and hand-off detection technology to reduce the occurrence of cellular incidents. On packet systems such as Motorolas RD-LAP, the bit stream is interleaved to spread burst errors. 4. The use of more powerful error correction coding techniques, deliberately sacrificing airlink capacity, in an attempt to deliver a clean message without retransmission. The most well known example of this class of modems are CDPD units. Wireless modems can be packaged as stand-alone units or, increasingly, integrated into paging devices, laptops, or cellular phones. Years of ground-laying packaging development for PC Cards has made fully integrated units a very powerful option. When modems are used on circuit switched cellular. vendor variations on the cellular instruments often force the need for an adaptive device, now a smart cable, between modem and cellular radio. These adapters mimic wireline dial operations for communications software. Increasingly, adapters are being integrated into either modem or cellular phone. Some modems contain the radio transceiver. Packet switched radio modems integrated into custom devices have been available from Motorola for more than a 16.2 MODEM COMPLEXITY 261 decade. Both Motorola and Ericsson began to deliver external radio modems at manageable price levels in 19921993. 16.3 CELLULAR SPEARHEADS MODEM DEVELOPMENT Multiple slow-speed modems capable of operating via circuit switched cellular were announced within a year of the initial cellular rollout in October 1983. Most were failures, but all contributed to the relentless trend toward lower weight and smaller physical volume. These physical improvements ultimately made device integration possible. For nearly six years the cellular modem physical trends were pleasant: a 300-bps modem in 1984 weighed 20 ounces; in 1990 a 1200-bps unit weighed the same 20 ounces; 300-bps units weighed 5 ounces. This compound annual weight reduction of ~20% and a compound bit rate increase of ~25% per year seemed a new law of physics and often appeared on forecast charts. The 1991 introduction of the Telebit QBlazer was the first break in the trend lines. This modem departed from the old modulation techniques, which were topping off at 4800 bps on wireline systems. Telebit employed V.32 (9600-bps) TCM as well as recovery strategies originally developed for wireline units. With the transmission speed reduced, typically to 4800 bps, these techniques made a good fit for cellular. Raw bit rates thus rose by a factor of 8; weights/volumes fell to one-third of the prior best: the V.32 Digicom 9624LE. The unit had V.42 error detection, with ARQ, and V.42 bis data compression, which had the potential for quadrupling throughput (see Section 15.4). This sharp break signaled the end of the medium-speed stand-alone modem. Excellent new units such as Microcoms MP1042, in normal times a breakthrough unit, were doomed by the V.32 development. Dozens of vendors 7 began to produce V.32 and the even faster V.32 bis pocket modems. Nearly all included fax capability as well. This tight packaging was made possible by the advent of inexpensive chip sets from AT&T, Exar, Rockwell, and Sierra. Three years later the nails were hammered ever faster into the stand-alone modem coffin. V.32 bis (14,400-bps) PC Card modems now weighed less than 35 gramsa little over an ounce. During much of this period list prices fell very slowly until the impact of wireline V.32/V.32 bis cellular-capable modems was felt. In the first quarter of 1985 Spectrum Cellulars Bridge/Span units delivered 300 bps for $595: 1 bit per second for ~$2. The coming of devices such as Megahertzs PC Card cellular modem permitted theoretical speeds up to 14,400 bps for a list price of $459: 1 bit per second for $0.03. Further, the new modems included many extras, including fax capability and communications software for both data and fax. In the first quarter of 1995 it was routine to find direct order retailers selling brand name cellular modems for $289: 1 bit per second for ~$0.02. By the fourth quarter of 1997 V.34 modems with cellular support could be purchased for $50$90 8 : 1 bit per second for about a half cent. This 400-fold price-per-bps decline in just 12 years ranks with the best technology shifts of the decade. 262 DEVICE ALTERNATIVES 16.4 VOICE/DATA PUSH–PULL 16.4.1 Positioning Tussles During the transition from stand-alone modem to PC Card, vendors were able to produce small OEM modems capable of being integrated into either data devices or cellular phones. Hybrid solutions were developed for each alternative. This competition over function placement, voice versus data centric, continues. 16.4.2 Voice Devices Swallow Modems In 1992 Mitsubishi integrated the Microcom 1042, a 2400-bps MNP10 modem, under the covers of its 1500MOB series phones. The resulting CDL300 was a 3-watt portable cellular phone with attractive physical characteristics for its time. With battery, it weighed 4.3 poundsnot bad for such a high-transmit-power machine. In 1993 PowerTek announced its CMI-3000 cellular data link. Rich with connection options, the CMI-3000 contained a 3-watt transmitter and a V.32 bis (14,400) bps data/fax modem using MNP10 correction and V.42bis compression. The identical unit was also offered by Audiovox as the CDI-1000. To add interest to the MNP10-versus-ETC dispute, both PowerTek and Audiovox claimed a 96% first-time connect rate 9 with MNP10. This may have reflected the high transmit power available in these rather large units. The PowerTek/Audiovox units made advertising claims for full integration but, like Mitsubishis CDL300, the handset was distinctly separate. In 1994 Air Communications announced a product that truly was fully integrated. Weighing in at 1 pound, the modem section was multiprotocol, including V.32 bis and fax. The device used the proprietary AirTrue enhancements to improve the probability of call connection as well as duration. The battery permitted 2 hours of data transmission. When disconnected from a PC it operated as a conventional cellular phone, with features such as voice mail. In this mode it served as an answering machine for incoming calls (16 minutes maximum time). Its storage capability also permitted it to hold up to 37 fax pages for later transmission to a fax machine. The Air Communicator was marketed by both Ameritech and Sprint Cellular, but in spite of diligent efforts, it failed. The philosophy of these voice-centric products is shown in Figure 16-2. The voice handset is the key communications device. The data user requires no modem within the laptop. A regular RS-232 cable connects the laptop to the phone modem. This modem can sometimes connect to wireline networks via normal RJ11 cables. Principally, it uses the voice radio to make a circuit cellular, facsimile, and, now, CDPD connection. 16.4.2.1 Voice Devices Try to Do It All In 1994 BellSouth announced IBMs Simon, a cellular telephone with limited PDA functions such as appointment scheduler and calendar, personal electronic directory, and calculator. Simon used a 16.4 VOICE/DATA PUSH–PULL 263 backlit liquid crystal display (LCD) screen as telephone keypad, pen annotation area, and computer display. Its communication functions were limited: 1. E-mail. Twenty messages could be received, but the data modem only operated at 2400 bps. There was no way to connect Simon to a PC and no wireline mode. 2. Paging . The coverage and costs were cellular based. Nine phone numbers (no text) could be received and stored. 3. Facsimile . Three facsimiles could be viewed on the small screen and hand annotated for retransmission. The BellSouth theme was Simon Says Have It All. Simon was occasionally spotted in the movies, rarely in real life. Ignoring ill-fated detours such as the AT&T EO440/880 class devices, the newest do-it-all unit is Qualcomms pdQ. 10 Sometime in 1999 we will see this voice cellular phone wrapped around a 3Com Palm Pilot. Two models were under test in the fourth quarter of 1998, an 800-MHz analog/digital voice version as well as a single-mode 1900-MHz digital-only unit. Three Qualcomm applications will exist to permit short-messaging service (SMS), E-mail (likely Eudora), and Web browsing. The resulting device is odd looking and fairly large, though smaller than a palm Pilot stuffed on top of a Minstrel modem. I felt faintly embarrassed putting a demonstration unit up to my face to talk. I also have trouble with the Palm Pilot as a pen-based data entry device. The pdQ price is unknown at this writing, so we must simply wait and see if the product(s) are successful. 16.4.2.2 A Compromise: SmartPhones PCSIs Unwired Planet Browser/ HDML-based PALphone was the first example of what was immediately tagged a smartphone. PDA functions are not integral to the phone instrument, as in Simon or the pdQ, but are obtained from the network from a built-in micro web browser. The address book and calendar (for example) can be located on your own personal Web page, which the smartphone accesses. The notion behind the smartphone was that many users (perhaps most) were voice junkies with a secondary need for data from the web or their own corporate network, especially one using Lotus Notes. There is only a tertiary need for any data input other Figure 16-2 Voice devices swallow modems. 264 DEVICE ALTERNATIVES than checklist yes/no responses. Entering any real message of substance from a telephone keypad is time consuming and unusually annoying. The PAL phone was, first and foremost, a cellular voice handset. But it had a good multiprotocol modem under the covers for CDPD, circuit switched cellular. and facsimile. It was all wireless, all the way; the RJ11 connection to wireline networks did not exist. Introduced in 1996, it was gone in May 1997, 11 an obvious casualty of the death of PCSI. Before its end, there was a feeling that the PALphone did not quite measure up to the smartphones that quickly followed, especially Samsungs Duette 12 and the Mitsubishi MobileAccess 110. 13 Initially priced at $500, they dropped to $300 by first quarter of 1998. 14 These units are now subsidized by the carriers. In the fourth quarter of 1998 AT&T Wireless offered units for $99 for those users subscribing to its WorldNet E-mail service. 15 AT&T Wireless bet heavily on these new devices with its PocketNet Service. The introduction 16 was all upbeat: I truly believe (smartphones) will be one of the major factors that finally drives (wireless data) adoption1996 and 1997 will be the years when the curve did start to turn up. But that hardly happened. Within months some customers in pilot opted to discontinue the service. 17 when they realized that the technology requires an IS department or an application from one of the (software developers) were working with. 18 AT&T Wireless was reasonably cautious about its equipment orders, awarding Samsung an $18 million dollar contract in June 1997 19 20% of what BellSouth committed to RIM for two-way pagers. In 1988 Mitsubishi began to ship its Mobile Access 100 series cellular phones, a greatly improved technology advance over 1992s 1500MOB phones. The multiprotocol Mobile Access phones have an extra cost PC/PalmPilot connection kit. 20 It provides a 34-in. cable and supporting software for Windows-based PCs, Palm III, PalmPilot Professional, and IBM WorkPads. The phone thus can act as a radio modem for connecting the data device to a variety of wireless (no wireline) options. 16.4.2.3 Annoying Residual Problems The current smartphone offerings are exclusively loved by zealots. Their voice clarity is only fair. 21 The display screen, at 4 × 12 (really only 3 × 12 for received messages) characters, is incredibly limited. Entering data makes one want to throw the instrument on the ground. Example: to enter the name DeRose (Nokia/Tegic T9 software is unlikely to find that name in a linguistic database) requires 18 key depressions and 6 pauses: Number of Keystrokes Sequence 1 D (pause) 3 Softkey, D, E (pause) 4 Softkey, P, Q, R (pause) 4 Softkey, M, N, O (pause) 4 P, Q, R, S (pause) 2 D, E (pause) 16.4 VOICE/DATA PUSH–PULL 265 Do not bother to attempt numbers. If you want to respond to the simple query what time shall we meet? with the four-character reply 2:30, one practical keypad sequence is 2, 2, 2, 2, pause, softkey, softkey, 0, 0, 0, 0, 0, 0, 0, 0, pause, softkey, 3, 0, softkey for another 18 depressions and 2 pauses. Tethered data devices, especially PCs, eliminate this human data entry problem, but it is particularly difficult to juggle two boxes, linked by a yard of cable, on a city street. Battery life is also found wanting. With the standard battery (when brand new), one can only get an hours talk time; standby time is 9 hours. As shown in Figure 16-3, if the phone is on standby for, say, 3 hours, the usable time drops to 40 minutes. The message: Always carry a spare battery and keep those chargers working every night. There are also qualitative problems with smartphones when using CDPD (at least BAMs version, Cellscape). Successful message transmission often takes 23 minutes of fussing: much sending)))), network not responding, retry, sending)))))), gateway not responding, and so on. Once or twice I decided to torment a BAM Cellscape phone by sending a long (500-octet!) message to it from another device. With BAMs network settings only about half the CDPD message is delivered initially. To see the balance, one must hit MORE, which results in the hateful sending))))) sequences. If a really long message (say 1500 bytes) is attempted in a difficult area (Grand Central Stations main Figure 16-3 “Talk” vs. standby time trade-off: PocketNet phones. 266 DEVICE ALTERNATIVES concourse is such a spot), you might as well buy a sandwich while you wait to read your mail. It is also extremely tedious to delete a received message: READ, ACT, sending))))), DELETE, sending))))), OK, sending))))), message deleted, OK, sending))))). Any one of the sending))))) sequences are vulnerable to network/gateway not responding responses, forcing a retry. After a while I simply gave up deleting messages and then gave up the phone. 16.4.3 Data Devices Swallow the Radio Data-centric devices containing the radio transceiver fall into three categories: 1. External radio modems for connection to the serial inputoutput (I/O) port of the terminal or PC. 2. PC Card radio modems for laptops, PDAs, and custom devices. Except in high-transmit-power applications, the PC Card radio modems have largely driven out their external predecessors. 3. Integrated units hidden under the covers of laptops or custom products. These are becoming increasingly popular in high-production-run, application-specific devices. An advantage often claimed for CDPD over competing alternatives is that there are many multivendor radio modems to choose from. 22 In truth, with the demise of Cincinnati Microwave and PCSI, the steady withdrawal of Coded Communications, Ericsson, IBM, and Motorola (for CDPD, for now), and the increasing marginalization of suppliers such as Uniden, the total number of radio modem suppliers for all carriers is remarkably small. It is likely that six to eight manufacturers account for 95% of all shipments to date. Of these, just seven vendors, four of them Canadian, dominate all current, in production, alternatives: 1. Dataradio : Has augmented its private radio offerings with its purchase of the Motorola R-net line in February 1998. 23 2. Megahertz : Provides PC Card radio modems for BSWD. 3. Metricom : Manufactures a line of external modems for cable connection to hand-held and notebook PC devices. The modems are designed in Richmond, British Columbia, by ax-Motorola (MDI) engineers. 4. Motorola : The only U.S. vendor, it offers a full line of radio modemsexternal, PC Card, other equipment manufacturer (OEM) modulesfor RD-LAP/MDC4800 (ARDIS) and Mobitex (BSWD). 5. NovAtel : Concentrates on small external devices and OEM modules for CDPD. 6. RIM : Specializes in integrated solutions, from OEM modules to custom products, for ARDIS and BSWD. 16.4 VOICE/DATA PUSH–PULL 267
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