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Comp 3 g Document Transcript

  • 1. A Compliment to 3G Joseph P. Urgento University of Texas at Austin EE 381K Multi-User Wireless Communications Dr. Jeff Andrews December 9th, 2002 1
  • 2. Table of Contents List of Figures and Tables 4 Abstract 5 I. Technologies 6 I.1. Multiple Access Technologies I.1.1. Time Division Multiple Access I.1.2. Code Division Multiple Access 8 I.1.3. Orthogonal Frequency Division Multiplexing 9 I.2. Duplexing 10 I.2.1. Frequency Division Duplexing 11 I.2.2. Time Division Duplexing I.3. IEEE Six Degrees of Freedom I.3.1. Modulation 12 I.3.2. Frequency I.3.3. Time 13 I.3.4. Code I.3.5. Space 14 I.3.6. Polarization 15 II. Current Technologies 17 II.1. 3G Cellular Technologies II.1.1. EDGE II.1.2. WCDMA or UMTS 18 II.1.3. HSDPA 20 II.1.4. CDMA2000 II.1.5. CDMA2000 EV 21 II.1.6. TD-SCDMA 22 II.2. 2G Wireless Broadband Technologies II.2.1. Navini Ripwave 23 2
  • 3. II.2.2. Flarion Flash-OFDM II.2.3. Beamreach BeamPlex 24 II.2.4. IP Wireless II.2.5. IOspan AirBurst 25 II.2.6. Others II.3. Antenna Enhancement Technologies II.3.1. Qualcomm Diversity 26 II.3.2. Lucent BLAST II.3.3. Nortel AABS 27 II.3.4. Other Antenna Enhancements III. A Compliment to 3G 28 III.1. Missing Killer Applications III.1.1. Wireless Broadband III.1.2. Portable Broadband 29 III.1.3. Dedicated IP III.2. Wireless Data Needs 30 III.2.1. All IP System III.2.2. Dormant States 31 III.3. Why 3G Data? 32 III.3.1. Phone Integration III.3.2. Mobile Wireless Data III.4. A Compliment to 3G 33 III.4.1. Two-tier Network III.4.2. Spectrum Allocation key to Success 34 III.5. Conclusion Appendix A: Compliment to 3G Comparison 36 Appendix B: Example Deployments 37 Appendix C: Acronyms 38 Appendix D: References 41 3
  • 4. List of Figures and Tables Figure 1.1. Frequency versus Time Diagram of typical 3-sectored GSM cell 7 Figure 1.2. Frequency versus Time Diagram of a typical single IS-95 CDMA Carrier 8 Figure 1.3. OFDM Tones 10 Table 2.1. Modulation and Coding Schemes for EDGE 18 Table 2.2. 3G Comparison 22 4
  • 5. Abstract This paper investigates several short comings of Third Generation (3G) wireless technology as an efficient wireless high data rate transport. Due its voice centric nature, 3G falls short in delivering high data rate speeds. However, 3G is an effective data solution for camera phones, PDA phones and telemetry applications and has proven so during its initial introduction. Further, non-line of site wireless broadband technologies being developed can compliment 3G as a more complete solution. Section one of this paper provides a foundation of knowledge for understanding the main points of the paper. This section starts with a comparison of the current multiple access technologies that dominate the 3G and wireless broadband landscape including; TDMA, CDMA and OFDM. Also, FDD and TDD duplexing is discussed and how each method provides advantages for two different needs. The last part of section one introduces IEEE’s six degrees of wireless freedom and how each degree of freedom can be exploited to enhance 3G and broadband wireless technologies. Section two of this paper introduces the current 3G cellular and 2G broadband technologies in the marketplace. 3G technologies are compared and contrasted based on their voice capacity and data rates. Next, the non-line of site broadband technologies are compared with 3G cellular technologies based on their data rates and spectral efficiency. Finally, several antenna technologies are introduced and described how they can increase spectral efficiency, voice capacity and data rates of wireless networks. The last section of this paper discusses why 3G needs a compliment. Due to 3G’s voice-centric technologies, it is incapable of providing a killer application, wireless broadband. The reasons for 3G’s shortfalls are reviewed, along with reasons why 3G is still needed to provide a complete wireless product. Finally, a two-tier wireless technology is suggested in order for wireless network operators to provide a complete solution to consumers needs. 5
  • 6. I. Technologies The goal of section one is to provide an introduction and a foundation of knowledge in order to more effectively convey the goals and points with in section three. To keep the wireless technology introduction brief and simple, it was divided into three categories; multiple access technologies, duplexing technologies and six degrees of wireless freedom. Multiple access technologies describe several common techniques that are used to allow multiple users to access a carrier frequency in order to create higher capacity for cellar networks. Duplexing describes different ways to have two-way or duplexed wireless communication. Finally, six degrees of wireless freedom reviews techniques used to increase the spectral efficiency of a wireless networks. I.1. Multiple Access Technologies Today there are two main multiple access schemes used in cellular networks, Code Division Multiple Access (CDMA) and Time Division Multiple Access (TDMA). TDMA was the first commercial multiple accessing technology that appeared in the early nineties in Europe as GSM or Global System for Mobile communications. CDMA was commercialized a few years later by Qualcomm as it appeared in a Korean and North American markets. Finally, OFDM or Orthogonal Frequency Division Multiplexing is a new technology that is close to being commercialized in cellular network by several emerging companies. I.1.1. Time Division Multiple Access TDMA is the multiple access of choice for several cellular technologies including US digital cellular (IS-136), Japan’s PDC (Personal Digital Cellular), Motorola’s iDEN (Integrated Digital Enhanced Network) and GSM, the most widely used cellular technology in the world. TDMA scheme is relatively simple; a frequency carrier is divided into time slots, so that more than one user can access that carrier at a time. For example, GSM has carriers that are 200 kHz wide and these carriers are divided into 8 unique time slots. Thus, up to eight different users can simultaneously access a particular carrier. 6
  • 7. TDMA is an efficient and simple way to get large number of users onto a relatively narrow slice of bandwidth. When used in voice centric networks, time slots are used to separate individual voice users which typically consume data rates between 9.6 and 14.4 kbps. In data-centric environments, these time slots can be combined to create higher aggregate data rates. However, TDMA carries a hindering flaw; it introduces a phenomenon known as frequency reuse. When TDMA is used in a multi-cell network, carriers in adjacent cells have to be separated in frequency so they will not interfere with each other. A typical cell frequency reuse number for today’s 3-sectored GSM cellular networks is 3. This basically means that each cell can only use a third of the available bandwidth that an operator owns. Thus, if a network operator owns 5 MHz of unidirectional spectrum, the operator would have a theoretical total of 25 carriers per cell to use (5 MHz/ 200 kHz). When calculating a reuse pattern of 3, the total number of carriers available per cell is reduced to 8. Figure 1.1 is a frequency versus time graph of a typical 3-sectored GSM cell. Frequency versus Time Diagram of typical 3-sectored GSM cell 8 Time slots per carrier 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 carrier dedicated to adjacent cell carrier dedicated to adjacent cell Frequency 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 carrier dedicated to adjacent cell carrier dedicated to adjacent cell 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 carrier dedicated to adjacent cell carrier dedicated to adjacent cell Time Figure 1.1. Frequency versus Time Diagram of typical 3-sectored GSM cell 7
  • 8. I.1.2. Code Division Multiple Access CDMA is a technology that was originally used by the United States government during World War II. With in the last 15 years, the technology has been developed and commercially deployed by Qualcomm. CDMA is currently used in IS-95 cellular networks, which is the second most widely used technology in the world. CDMA is also the foundation for the 3 main third generation (3G) technologies WCDMA, TD-SCDMA and CDMA2000. Currently, CDMA2000 is the most widely deployed third generation technology in the world. CDMA is a little more complex than TDMA. The basic idea involves assigning each user a unique code and encrypting each users’ data streams with these codes. Next, the users’ data streams are interleaved into narrow band carriers. Then, each narrow band carrier is spread over a large RF carrier for transmission. The total number of users is limited by interference. Additional users can be added to the system until a tolerable limit of interference is reached. Like TDMA, groups of users can combined to create peak burst data transmission rates. Figure 1.2. is a diagram of a typical IS-95 CDMA carrier. Frequency versus Time graph of a typical single IS-95 CDMA Carrier User 1 User 2 User 3 User 4 User 5 User 6 User 7 User 8 Users interleaved and spread over Frequency User 9 wideband carrier separated by code User 10 User 11 User 12 User 13 User 14 User 15 User 16 Time Figure 1.2. Frequency versus Time Diagram of a typical single IS-95 CDMA Carrier 8
  • 9. An advantage of CDMA is that has a soft capacity because it does not have a fixed user slot size like TDMA. New voice coding algorithms and voice detection techniques are emerging allowing individual users to be squeezed with in smaller data rates. Decreasing the amount of bandwidth of each individual voice user allows room for more total voice users on a CDMA cellular network. With TDMA systems, each user’s time-slot is synchronized with each other. Thus, their slot sized can not vary and it can only be halved. The only way for TDMA to increase the number of users per carrier is to half each user’s voice user bandwidth. CDMA, on the other hand, can take advantages of incremental decreases in individual user bandwidth. Also, CDMA has a reuse pattern of one, which is key for capacity in both voice and data networks. Every cell can use all carriers available to an operator. Also, capacity can further be increased by sectoring or dividing the cells. If a cell is divided into three sectors, then its capacity can increase by a factor of three. In TDMA network, sectoring can be used to lower the cell reuse number, but the carriers have to be further divide their spectrum among the sectors. These two advantages will attribute to the world’s cellular networks shifting from a TDMA based system to a CDMA based system over the next five to ten years. I.1.3. Orthogonal Frequency Division Multiplexing OFDM is technology that was first idealized in the 1970’s, but due to processing power its commercialization could not be realized until recently. Currently, many cellular and network operators are trialing this technology as an opportunity to implement high speed wireless data networks. OFDM separates data onto many narrow band frequency carriers. These carriers are spaced so that their side lobes cancel each other out, thus creating a tightly grouped transmission medium. Figure 1.3 conveys these tightly packed narrow carriers. A tremendous advantage with OFDM is its resistance to multi-path or the degradation of a signal due multiple reflections of the same signal interfering with each other. Data is transmitted independently on each frequency carrier. Because each carrier is so close to the next, data can be sent less frequently on each carrier and still maintain data rates 9
  • 10. similar to other technologies. Because of the increased time spacing between data transmissions, OFDM has a higher resistance to multi-path interference. Figure 1.3. OFDM Tones OFDM by it self does not constitute a multiple access technology, it has to be combined with TDMA, CDMA, DSSS (Direct Sequence Spread Spectrum) or Frequency Hopped Spread Spectrum (FHSS) to effectively separate the users. DSSS is essentially the same concept as CDMA; it spreads multiple narrow band information over a wider transmission carrier. FHSS simply describes the process of systematically hoping between these orthogonal frequencies over a spread spectrum of carriers to avoid interference. In a multi-cell, mobile network, OFDM will have to use FHSS or DSSS to achieve a reuse of one. It is difficult to achieve a reuse number of one with a TDMA scheme on an OFDM carrier. I.2. Duplexing Duplexing describes the ability to conduct two-way communication. In a cellular network, duplexing is the ability of the network to communicate with the end user (downlink) and end user with the network (uplink). Currently, there are two fundamental ways of allowing two-way communications, Time Division Duplexing and Frequency Division Duplexing. 10
  • 11. I.2.1. Frequency Division Duplexing FFD divides the uplink in the downlink by frequency. The network communicates with the user on unique frequency carrier and the user communicates with the network on an entirely different frequency carrier. FDD is ideal for synchronous traffic such as voice traffic on cellular networks. FDD is also simple to implement where full duplex communication is desired. Most cellular operators have to purchase licenses for the radio waves they broadcast on. These licenses are sold in pairs, so when an operator purchase 30 MHz of spectrum, it is sold in two 15 MHz blocks. For these reasons, FDD is the most widely deployed duplexing technique with in cellular networks. I.2.2. Time Division Duplexing TDD combines the uplink and downlink on a single carrier. Each link is divided into time slots and can be broadcast simultaneously. Depending on network needs, the carrier can dynamically shift the time slots to carry more uplink or downlink traffic. TDD would be ideal for asynchronous traffic, such as data networks, where the downlink carries most of the traffic. Also, TDD is theoretically more efficient than FDD because it can communicate on half the bandwidth. However, TDD does have its disadvantages. It is more complex to implement and monitor on a cellular network than FDD. Due to strict synchronization needed to separate uplink and downlink traffic, cell radius is limited. Also due to synchronization, clearer channels are required or transmission and communication will be limited. I.3. IEEE Six Degrees of Freedom According to IEEE, there are six different degrees of freedom that can be exploited to increase the spectral efficiency with in wireless systems. These six degrees of freedom are modulation, frequency, time, code, space and polarization. Spectral efficiency can be measured by bps (bits per second)/Hz. Since spectrum is limited and measured in hertz, the idea is to squeeze more bits per second per hertz. By increasing the spectral efficiency, voice capacity can increase, data rates can be faster and the network can create more revenue and be more cost efficient. 11
  • 12. I.3.1. Modulation Modulation describes the process of converting digital bits into analog pulses or symbols to be transmitted through the air. Typical modulation techniques include BPSK, (Binary Phase Shift Keying), GMSK (Gaussian Minimum Shift Keying) and QPSK (Quadrature Phase Shift Keying). BPSK and QPSK are used in IS-95, GMSK is exclusively used in GSM and QPSK is used in most 3rd generation technologies including CDMA2000 and WCDMA. Theoretically, each Hz of spectrum should be able to transmit one modulated symbol. GMSK and BPSK can modulate two different shaped symbols. One symbol represents a one and the other a zero and together they represent a bit. QPSK can modulate four different symbols representing two bits. There are other higher order modulation techniques such as 8 PSK or 8 Phase Shift Keying (8 symbols, 3 bits) and 16 QAM or 16 Qaudrature Amplitude Modulation (16 symbols, 4 bits). There are extremely advanced modulation techniques with as many as 256 unique symbols which can represent as many as 8 bits. More bits per symbol equate to increased capacity and faster data rates. However, the greater number of symbols requires greater detail in the symbol shape and a need for a cleaner channel to transmit them through. Higher order modulation techniques have a greater chance of interference than lower order modulation techniques. Most wireless systems can not guarantee a clear enough channel for full-time higher modulation and thus lower modulation is used. With today’s processing power, exploitation of modulation is simple; adapt the modulation to the link quality. When the channel is clear, use a higher order modulation and when it is not, use a lower order modulation. Future 3G cellular and wireless broadband technologies will use adaptive modulation. I.3.2. Frequency Frequency was the first degree of freedom that was exploited in wireless technology. If there is a limitation on number bps per hertz, simply reuse the frequency or hertz as many times as possible with in a geographic space. One way is to divide a 12
  • 13. geographic region into cells and confine the transmission of a set of frequencies with in that cell. This is the concept behind cellular technology. Another way to exploit frequency is to sector or divide the cells so the frequency can be reused with in a cell. Most advanced wireless networks use three sector cells. Three sector cells in a CDMA network allow frequency to be reused three times with a cell and triple capacity. TDMA systems sector cells to reduce interference and decrease their reuse pattern numbers, which increases capacity, but not as much as CDMA. I.3.3. Time Time is another degree of freedom that was exploited early in wireless development. By dividing a channel into time divisions and assigning users to each time division, more users can access a network. TDMA was the first widely used multiple access technique and even though it is being replace by CDMA, it is being used to enhance CDMA. Many of the high data rate 3rd generation CDMA technologies, time is being used to further divide the users to create efficient, faster data streams. ARQ (Automatic Repeat Request) algorithms are another way to exploit time as a degree of freedom. New hybrid ARQ algorithms are being developed to ensure that transmitted packet size is optimal for current channel conditions. If packets are too large, they will incur too many errors over the wireless link and drop. Every time a packet is dropped it has to be requested and transmitted again taking away from realized throughput. If packets are too small, more information contained by the packet will be overhead and not data, which also reduces realized throughput. ARQ algorithms take into consideration the immediate history of the channel and thus channel information must be shared quickly. ARQ algorithms optimize packet size and thus the length of time for transmission to reduce the number of repeat request of dropped packets and reduce the overhead to data ratio. I.3.4. Code Code is a degree of freedom that can be exploited in numerous ways and it is the foundation for CDMA technology. Many of the techniques that exploit the code degree of freedom enhance the performance of CDMA. Several of these techniques included 13
  • 14. Multi-User Detection (MUD), Signal Interference Cancellation (SIC) and Adaptive Error Control. MUD is a complicated theory and technique. The basic principle involves detecting other CDMA users and knowing their characteristics. With this information, an optimal channel can be created for most users which can increase capacity. MUD is a controversial technique that is currently being evaluated to be deployed in future CDMA based systems. SIC is a technique that is used to increase the individual performance by canceling out other CDMA users’ interference. If each user could effective create a cleaner channel for them selves, then overall system capacity will increase. SIC is also being evaluated for use in future CDMA wireless networks. Error control code is being studied for all multiple access technologies. With each multi-access technology there is a predetermined bandwidth that is allocated for users. Part of this bandwidth is used to transmit error control code, which is overhead and reduces system capacity. Error control is used to reduce the bit errors that are introduced in an unfavorable link. For voice centric systems, the amount of error code is usually fixed. However, in data centric systems, that amount of error control code can be reduced if a link becomes clearer, thus increasing the amount of bandwidth for transmission. Adaptive error control alters the amount of error control used to optimize data transmission speeds and can create extra capacity with cleaner links. I.3.5. Space Exploiting space or distance within a wireless environment is currently a hot topic in wireless research. Currently there are two main research focuses, MIMO (Multiple Input Multiple Output) and Beam-forming. MIMO involves placing multiple antennas at the BTS (Base Transceiver Station) and at the user equipment. MIMO creates several opportunities to exploit space with in a wireless network. Air as a transmission medium is inherently unreliable. Due to a changing environment, Raleigh fading is most likely to occur and cause link outages between the BTS and the user. MIMO is an effective way to create redundant links between the BTS and the user. For example, if there are 4 antennas at the BTS and 2 at 14
  • 15. the user, then there are 8 total links (4 X 2) between them. If each link has a high outage probability of 30%, then outage probability that all 8 will fail simultaneously is 0.0066% (30% ^ 8). Since MIMO can effectively create a cleaner channel, system capacity increases and user coverage is extended. MIMO creates other opportunities including the ability to use higher order modulation techniques, which can increase data throughput for individual users. Higher order modulation techniques can only be used in relatively clean channels. Due to the complex symbols that are transmitted, poor quality channels will distort the symbol constellations and make higher order modulation impossible. MIMO can combine information from multiple links and piece together a complex symbols and their constellations allowing the use of higher order modulation. MIMO can also be used to send information in parallel data streams, effectively reusing frequency for a specific user and multiplying their data rates. Using the previous example, assume that only 2 of the 8 links are needed to create a clean channel for transmission. The remaining six links can create as well creating four independent data streams, which theoretically quadruples the data throughput. Beamforming is another way to exploit the spatial degree of freedom. Beamforming can be described as projecting beams of RF energy to specific areas with in a cell or sector. The beams would typically be directed to areas with a dense number of users. Multiple beams can be projected with in a given cell and each beam can use the entire frequency dedicated to a carrier. Beamforming essentially creates additional sectors or sub-sectors with in a cell or sector, which allows frequencies to be reused several times with that given cell or sector. The further reuse in frequency creates more capacity for the network. These beams can also be adaptive and vary their direction based on shifting traffic conditions. This technique can further increase capacity. I.3.6. Polarization Polarization is the degree of freedom that is being researched the least and is the furthest from being implemented. The idea behind polarization is that all electromagnetic energy has perpendicular axis. If it is possible to transmit and receive RF energy on two or three of these axes, then the transmission medium has doubled or tripled in available 15
  • 16. bandwidth. It seems like one of the simplest concepts, but due to uncontrolled and changing environments, it will be one of the hardest to exploit and implement. 16
  • 17. II. Current Technologies The goal of section two is to review the prominent 3G cellular and 2G non-LOS broadband technologies in order to realize how to implement and deploy the suggestion made in section three. For each technology, the main specifications are compared including; voice capacity, realistic aggregate throughput and spectral efficiency. Finally, an introduction is made in antenna enhancement technologies. These technologies will create tremendous capacity benefits for both 3G cellular and 2G non-LOS broadband technologies. II.1. 3G Cellular Technologies The term 3G cellular technology refers to Third Generation wireless technology. First generation cellular is based on analog transmission. Second generation technology refers to digital cellular systems like IS-95 (CDMA), IS-136 (USDC) and GSM, which created tremendous capacity gains over analog technology. Finally, 3G refers to enhanced digital cellular systems that have packet based transmission speeds of at least 144 kbps. II.1.1. EDGE EDGE (Enhanced Data rates for Global Evolution) is an enhancement to the GSM cellular technology. Thus, EDGE uses the same carrier bandwidth of 200 kHz and has the same reuse pattern of 3 or 4. EDGE can combine up to eight GSM timeslots to create theoretical burst speeds of up to 473.6 kbps. However, these speeds will rarely be seen in a commercially deployed system. Realistic speeds are based on available time slots, modulation technique and amount of error control used. The number of available time slots varies based on the number of voice users accessing the system. Each voice user will effectively take away a time slot available for bursting data traffic. Also, EDGE, like GSM, uses GMSK modulation which can transmit one bit per symbol. However, depending on equipment, channel clarity and system design, 8-PSK can be used, which transmits 3 bits per symbol effectively tripling the burst speed. Finally, the amount of error control can be reduced to increase effective transmission speed. Typically, the majority of bits used for GSM data transmission are 17
  • 18. used for error control. With, EDGE, error control overhead can be reduced to less than 5% which can create an additional doubling of transmission speeds. Table 2.1. displays the nine different modulation and coding schemes available for EDGE. Modulation and Coding Schemes for EDGE Aggregate 8 Raw Slot Forward RealSlot Slot Scheme Modulation Throughput Error Control Capacity throughput (kbps) (%) (kbps) (kbps) One GMSK 21.4 143 8.8 70.4 Two GMSK 21.4 91 11.2 89.6 Three GMSK 21.4 45 14.8 118.4 Four GMSK 21.4 22 17.6 140.8 Five 8-PSK 64.2 187 22.4 179.2 Six 8-PSK 64.2 117 29.6 236.8 Seven 8-PSK 64.2 43 44.8 358.4 Eight 8-PSK 64.2 18 54.4 435.2 Nine 8-PSK 64.2 8 59.2 473.6 Table 2.1. Modulation and Coding Schemes for EDGE Some EDGE systems shipping from vendors include half-rate codecs, which transmit with similar voice clarity of traditional GSM codecs and use half of the bandwidth. Depending on the handsets used on these systems, the number of available voice time slots could double to 16. This could increase data capacity as voice users share time slots, thus keeping more time slots open for data bursts. EDGE is extremely spectrally efficient, but because its reuse number is greater than 1, it will have less system capacity CDMA based systems. II.1.2. WCDMA or UMTS Universal Mobile Telecommunication System (UMTS) is a marketing name for Wideband CDMA or WCDMA. The wideband description is added due to the large 5 MHz carrier it uses as apposed to the 1.25 MHz carriers of a narrower band CDMA 18
  • 19. technology like IS-95. As for modulation, UMTS uses QPSK for the uplink and the downlink. UMTS uses a spreading factor of 256 for the uplink, which could mean up to 256 different users. Due to overhead, the theoretical max number of simultaneous voice users is reduced to 196. However, due to harsh channel conditions, data needs to be redundant to insure the Quality of Service (QOS) need for voice traffic. Thus, in realistic conditions Ericsson has only been able to accommodate 57 simultaneous voice users. As codecs, antennas and overall technology improves, this number could move closer to the theoretical limit. For data transmission, the total aggregate bandwidth available for downlink is 2 Mbps. However, this is a theoretical limit and typical peak downlink transmission speeds are around 384 kbps. UMTS has plagued by three main issues; bandwidth requirements, backwards compatibility and certification. Again UMTS uses 5 MHz carriers per link. This means to deploy just one channel of UMTS, 10 MHz of bandwidth must be available to a carrier. Most operators that will eventually migrate to UMTS currently use GSM. Due to GSM reuse pattern of 3 or 4 and the popularity of mobile phones, operators due not have 10 MHz open. So operators had to purchase extra spectrum for UMTS. Auctions made the price of spectrum so high, that no body could afford to pay for the spectrum they won. Bottom line is, even though UMTS equipment has been available for some time, only one operator, NTT DoMoCo has had the means to deploy it. However, the cost of their deployment was so high, the end users cost became practically unaffordable. Thus DoMoCo has only racked up a few hundred thousand 3G subscribers in a year compared to the millions of subscribers it acquires on its 2G network every quarter. Also, WCDMA is not backwards compatible with the standards it replaces. This means one of two things must happen; either operators will need to upgrade its entire network and all their roaming networks at the same time or dual-mode handsets need to be produced. Since neither of these scenarios are happening, migrating customers effectively loose coverage, which slows down adoption and negatively impacts ROI. Another hindrance to UMTS is slow certification approval. Version 99 of UMTS was approved in 1999 and the next revision was not due for a while. NTT DoMoCo choose not to wait for a better revision and is currently deploying version 99. Since then 19
  • 20. version 4 was approved and it is supposedly not compatible with version 99, which will create roaming and unification issues in the future. Also, many carriers are choosing to deploy UMTS when Version 6 is approved in 2004. Version 5, which is compatible with version 4 is due out soon and it will optimized downlink data transmission. II.1.3. HSDPA The main feature that will be added in version 5 is High Speed Download Packet Access. HSDPA will further divide the carrier into time slots, have better coding algorithms and can use 16 QAM modulation under clear channel condition. Both of these improvements will increase the theoretical downlink transmission to 8-10 Mbps. Currently, realistic throughput can only be estimated. The high throughput potential makes HSDPA extremely attractive, but the 10 MHz of bandwidth needed to implement a single carrier may be its down fall. II.1.4. CDMA2000 CDMA2000 is the natural 3G upgrade to IS-95. CDMA2000 is fully backwards and forwards compatible with IS-95 making it easy to upgrade to and deploy. Both IS-95 and CDMA2000 use 1.25 MHz carrier width and QPSK on the downlink. CDMA2000 uses QPSK instead of Orthogonal-QPSK on the uplink. Both IS-95 and CDMA2000 separate their users on the downlink via 64 different Walsh codes, which would mean up to 64 different simultaneous users. Again, due to QoS and redundant transmission, IS-95 could typically carry 16 simultaneous voice users with an 8 kbps EVRC codec. Due to better signaling and coding efficiencies, CDMA2000 can almost double the voice users to 29 with the same codec. Even with out increased data throughput, this capacity improvement makes CDMA2000 deployment attractive for IS-95 operators. As for data, CDMA2000 is capable of combining up to 16 unused voice 9.6 bps codes to create aggregate data throughputs up to 153 kbps. In a future release of CDMA2000, up to 32 different voice codes can be combined to create data throughput up to 307 kbps. Due to it’s compatibility with IS-95, voice capacity and data throughput improvements, CDMA2000 is the fastest growing and most widely used 3G technology 20
  • 21. in the world. In fact, due to its capacity advantage, standards stability and relatively narrow carriers, many IS-136 TDMA, GSM and new operators are deploying CDMA2000 networks. II.1.5. CDMA2000 EV CDMA2000 EV stands for CDMA2000 Evolution. Currently there is a Data Optimized or EV-DO version being deployed throughout the world. EV-DO is a CDMA2000 carrier dedicated to only data traffic. The EV-DO carrier has been further multiplexed via time to create efficient varying time slots for bursting packet transmissions. EV-DO has also been enhanced by using 8-PSK and 16 QAM modulation (3 bits per symbol and 4 bits per symbol respectively) in addition to the standard QPSK (2 bits per symbol) modulation used CDMA2000. With these enhancements, EV-DO can transmit data in burst as high as 2.4 Mbps with a 1 Mbps sustained rate. Recently, EV-DV (Evolution-Data Voice) has been finalized and commercial equipment is currently being developed for deployment. EV-DV can transmit both voice and data traffic on the same carrier. Recently, peak data throughput for EV-DV has been confirmed at 3.09 Mbps. Table 2.2. compares the prominent 3G technologies and their aggregate number of users and mean data throughput. 21
  • 22. 3G Comparison: Total users & Aggregate Throughput per Cell using 3-Sectored Cells & 10 Mhz of Spectrum Voice Total Max DL Avg. DL Mean DL Spectrum RF carrier RF Users voice Sector Carrier Estimated Cell Technology (MHz per bandwidth Reuse carriers per Throughput throughput users Throughput link) (MHz) per cell Carrier per cell (Mbps) (Mbps) (Mbps) (est.) (est.) GSM/ EDGE 5 0.2 9 8.3 8.0 0.474 0.150 67 1.25 WCDMA 5 5 1 3.0 57.0 1.920 1.000 171 3.00 CDMA2000 5 1.25 1 12.0 29.0 0.307 0.288 348 3.46 CDMA2000 EV DO 5 1.25 1 12.0 0.0 2.543 1.100 0 13.20 CDMA2000 EV DV 5 1.25 1 12.0 29.0 3.090 1.400 348 16.80 Table 2.2. 3G Comparison II.1.6. TD-SCDMA Time Division-Synchronous CDMA is the least well known of the approved 3G standards. TD-SCDMA is being developed by Siemens for Chinese carriers. Due to its audience, TD-SCDMA has the potential of reaching 100’s of millions subscribers TD-SCDMA uses QPSK and 8-PSK modulation and it has data transmission capabilities of up to 2 Mbps. TD-SCDMA uses a 1.6 MHz TDD carrier where as CDMA2000 uses a 1.25 MHz FDD carrier (1.25 MHz uplink & downlink, 2.5 MHz total). The TDD allows TD-SCDMA to use only one carrier for both uplink and downlink, which means it requires the least amount of spectrum to deploy. II.2. 2G Wireless Broadband Technologies When wireless broadband was first trialed and deployed, current technology required LOS (Line of Site) transmission to achieve the speeds desired for broadband applications. To insure that users antenna was positioned optimally, technicians were required to install the user equipment. The cost of this install drove up the upfront cost of 22
  • 23. the system to the operator and created an unfavorable ROI. This fundamental failure created the need for Second Generation (2G) non LOS technologies. Also, LOS systems typically used super cell architecture, meaning that one tower would cover a radius close to 30 miles. The 2G non LOS systems could not transmit over such large distances, thus their target customers where cellular operators that already had towers in place. Reusing existing infrastructure keeps network deployment cost in line with a super cell network deployment. II.2.1. Navini Ripwave Navini Networks out of Dallas Texas, has developed a 2G wireless broadband system that is based on TD-SCDMA. The system named Ripwave uses beamforming to allow multiple subscribers in different parts of a sector to simultaneously use the majority of spectrum bandwidth. The Ripwave system varies between QPSK, 16 and 64-QAM modulation, which allows the system to burst over 4 Mbps using single 1.6 MHz TDD carrier. Due to TDD and 64-QAM modulation the Ripwave system is extremely spectrally efficient. Beamforming will allow the spectrum to be effectively reused in dense environments without having to use excessive sectors. Currently Ripwave is being trialed by several national telecom operators and is implemented in several smaller networks. The customer CPE is about the size of a cable modem and has a self contained antenna. Currently, PC cards for laptops are being developed. II.2.2. Flarion Flash-OFDM New Jersey based Flarion Technologies is promoting their Flash-OFDM solution as legitimate high speed wireless broadband solution. Flash-OFDM uses FHSS to limit interference and allow a reuse pattern one in an OFDM environment. Flarion’s Flash- OFDM system uses 1.25 MHz FDD carriers with QPSK and 16-QAM modulation. Peak speeds can burst up to 3.2 Mbps with sustained rates stabling out at 1.5 Mbps on the downlink. Flarion is one of the few wireless broadband technologies that has not implemented an antenna enhancement technology. The spectral efficiency of the Flash- 23
  • 24. OFDM is good and can be further improved with MIMO or Beamforming technologies. Flarion’s Flash-OFDM is being trialed by several domestic and international carriers. II.2.3. Beamreach BeamPlex California’s Beamreach Networks has developed Beamplex, a wireless broadband technology based on OFDM and beamforming. Beamplex uses TDD duplexed 1.25 MHz paired carriers. Spread spectrum is used to reduce interference over the 2.5 MHz carriers allowing a cellular reuse of one. Individual users can expect download rates of 1.5, 1.2 and 0.8 Mbps using 32-QAM, 16-QAM and 8-PSK modulation respectively. The aggregate network bandwidth is claimed to be 88 Mbps in 10 MHz of spectrum or 220 Mbps in 24 MHz of spectrum. With claimed system spectral efficiency close to 10 bps/Hz, Beamreach is doing something special. Upon further inspection, it should be noted that system uses either 4 or 6 sectors and these claims are based on those sector schemes. For any technology with a reuse number of one to achieve 10 bps/Hz per cell with 4 or 6 sectors, the efficiency in each sector would need to be a reasonable 2.5 or 1.6 bps/Hz respectively. II.2.4. IP Wireless IP Wireless is an U.K. based company that developed a 2G broadband technology based upon UMTS. However, instead of using FDD duplexing, IP used TDD which reduces the amount of spectrum needed to deploy a single carrier to 5 MHz instead of 10 MHz like true UMTS. IP Wireless uses QPSK and no advanced antenna techniques. The theoretical peak transmission speeds for a 10 MHz deployment is 6 Mbps downlink and 3 Mbps uplink. Even though using TDD is a tremendous advantage in data centric wireless networks, IP Wireless system is based on one of the least efficient 3G technologies, UMTS. Also, the IP Wireless system only uses QPSK modulation and no advanced antenna technologies. Theses factors contribute to its poorer spectral efficiency, which is evident in its mediocre transmission speeds for such wide carriers. Since IP wireless is based on UMTS, the development of HSDPA should be able to significantly improve data transmission speeds. 24
  • 25. II.2.5. IOspan AirBurst IOspan has gone out of business during the research of this paper. They are still being including in this paper due to their impressive technology and with the hopes that they can find more funding or be bought out by a another technology company. The Airburst system is based upon MIMO and OFDM. Airburst uses adaptive modulation that is capable of up to 64-QAM modulation on 2 MHz FDD carriers. IOspan has incorporated MIMO so that if conditions persist, parallel data stream can be pushed over the same frequency in the same sector on different sets of antennas. IOspan conducted test with sustained rates of 13.6 Mbps over a 2 MHz carrier across a distance of several miles. II.2.6. Others There are many other developing wireless broadband companies and technologies including Arraycomm’s i-Burst, LinkAir’s LAS-CDMA and Tantivy’s I-CDMA. The five technologies that were acknowledged in this paper were chosen based upon available details of their systems or near commercialization of their products. Defining features of 3G cellular and wireless broadband technologies including; duplexing, carrier bandwidth, modulation, data throughput, spectral efficiency and IP readiness are compared in Appendix A. II.3. Antenna Enhancement Technologies There are many way to increase capacity in a wireless network. One on the simplest and most effective enhancements are advanced antenna solutions such as diversity, MIMO and beamforming. Another attractive feature about advanced antenna solutions is that they are somewhat technology agnostic. Even though the results may vary across different multiple access technologies, a significant improvement can be evident in most cases. 25
  • 26. II.3.1. Qualcomm Diversity Qualcomm is working on an antenna technology that will place two or diversity antennas at the mobile phone. To keep the cosmetics of the phone similar to current phones, the second antenna is manufactured onto the circuit board. The second antenna essentially creates second link between the BTS and the handset. This second link acts as a redundant connection which can be used if the first link fails or can be used to transmit advanced modulation and coding schemes. Qualcomm has successfully tested this enhancement on CDMA2000 and EV-DO networks. In each network, gains of around 3 dB have been consistently achieved. A 3 dB gain in a CDMA2000 can equate to doubling in voice capacity. Essentially, the gain enables to network to more effectively use the 64 available Walsh codes and increase typically max number of users in a CDMA2000 system from 29 to greater than 50. Similarly, a 3 dB in an EV-DO network can equate to a doubling in aggregate network throughput. With out diversity EV-DO would typically achieve sustained data rates of 600 kbps. With diversity EV-DO can consistently achieve sustained data rates over 1 Mbps. II.3.2. Lucent BLAST Bell Labs Layered Space Time or BLAST is a MIMO based antenna enhancement. Lucent has 3 different phases to BLAST and recommends an appropriate phase based upon carriers’ financial position and capacity needs. The first phase involves adding a second transmit antenna introduced at the BTS, which creates a second transmission path with in the system. The second phase involves adding a second pair of antennas at the BTS, which creates two additional transmission paths for a total of four. Phase two also introduces some beam steering capabilities. The third phase or “Full BLAST” involves placing 4 antennas at the BTS and the mobile unit, which can create up to 16 unique transmission paths. For phase one and two, the additional paths are used to ensure a higher quality link is available a greater percent of time. In certain conditions, these higher quality links can allow transmission with higher modulation or increased coding rates, which can 26
  • 27. significantly improve capacity and data throughput. As for the third phase, the 16 available transmission paths allows BLAST to create up to four simultaneous unique data streams which quadruples data throughput. Phase three also allows for higher modulation and coding schemes. II.3.3. Nortel AABS Nortel’s Adaptive Antenna Beamforming Selection or AABS is smart antenna technology that allows frequency to be reused with in the sectors of a cell. AABS creates up to three separate beams of RF energy to be dispatched to dense traffic areas of a sector. Each beam can effectively reuse the entire bandwidth available to the sector, which theoretically triples the capacity of the system. In addition to beamforming, AABS also incorporates transmit diversity to assist in improving link performance. AABS has proved to be successful with operator trials in commercially deployed systems. Individual gains have been consistently above 4 dB which translate into a 70 to 100 percent increase in system capacity. A tremendous advantage to AABS is that implementation is only needed at the BTS allowing an operator to see immediate results when deployed. Other antenna technologies usually require enhancements to the mobile, which means that benefits are not realized until the subscriber mobile units have been significantly penetrated with the new technology. When operators have millions of customers, it may take years for half of their subscriber base to upgrade to newer technologies. II.3.4. Other Antenna Enhancements Again, other antenna enhancement companies and technologies are available such as Arraycomm and Metawave. The three particular antenna enhancement technologies acknowledged in this paper were chosen base on availability of commercial trial results. 27
  • 28. III.A Compliment to 3G 3G cellular technology was introduced to commercialization later than originally anticipated. Recently in 2002, 3G has seen an explosion in growth in form of CDMA2000 as it gains millions of subscribers per month. Many new data devices and applications such as camera phones, PDA phones, micro browsing and advanced messaging are quickly expanding in the market place. 3G has provided faster data transmission speed that these devices and applications desperately needed. However, something is missing; there are killer applications that 3G is inadequate for. These killer applications can provide additional subscribers with entirely new revenue streams. The applications mentioned previously only create small amounts of additional revenue from existing subscriber base. This additional revenue is needed and helps the operators bottom line, but subscriber additions are slowing through out the world and new application are needed to drive not only incremental revenue but more importantly, additional subscribers. III.1. Missing Killer Applications What is the only technology that has been growing at the same rate as cellular phones, the Internet. The world is shifting to a new paradigm where knowledge is power and sharing information is key to progress. The Internet is most efficient means of sharing information on earth. The number of people on this earth that have access to the Internet is almost 500 million. However, less than 50 million people have broadband access. The question is, how much more value is there with high speed access to the internet. Here is the answer, give anyone broadband access for one week. Then, take it away and give that same person a dial up connection. III.1.1. Wireless Broadband The biggest inhibitor to broadband growth is a medium to transmit it over. In Europe and Asia, regular landline telephony typically cost $50 to $100 per month. Due to these high cost, many international users no longer use personal landline telephony. This alone is the biggest reason why cellular phone penetration is so high in these 28
  • 29. countries. If landline telephony is expensive, how much is broadband access in these countries? In the United States, how many apartment homes or rural areas have high broadband cost, slower broadband access or no broadband access at all? The cost of bringing a suitable copper or coaxial cable to everyone home drives up cost, reduces availability and limits subscriber growth. Many new wireless broadband technologies are being developed that can provide broadband speeds that can reuse previously deployed cellular towers and infrastructure, which creates a simple, cost effect deployment. Most wireless broadband technologies are designed to be implemented in a cellular type network. In the United States, there are six national and three regional carriers with tens of thousands of constructed cellular towers. Similar infrastructure is deployed through out the world as well. As for the subscriber, newer wireless broadband technologies include non- LOS Customer Premise Equipment (CPE) that can be self installed. III.1.2. Portable Broadband A simple enhancement could be made to wireless broadband that could increase incremental revenue and possibly attract more subscribers. Make it portable. Wireless broadband is free from using wires for transmission. Why not make the CPE battery powered or fit into a PC card for laptops? If an operator can limit which sectors and cell sites a subscriber can access. A premium can be charge for allowing a subscriber to roam or travel across the entire cellular network. In the United States alone, there are over 50 million mobile workers, most of whom already have cellular phone bill that is decreasing every year. Why not double the subscriber base and possibly revenue by adding a service that will increase productivity in today’s slumping economy? III.1.3. Dedicated IP Another way to increase the potential of wireless broadband is to offer dedicated slices of bandwidth at premium prices to business. Dedicated IP bandwidth, such as T1 or T3, are typically charged from several hundred to several thousand dollars a month. Most of the cost associated with the service is to return the investment made in laying the fiber or copper. Wireless Broadband will alleviate most of those cost and allow operators 29
  • 30. to provide dedicated IP at significant reduced prices and increase profit margins. As wireless broadband improves, it will be a matter of time before dedicated multi-megabit speeds can achieved on a wireless link. Further more, it might be possible to offer even greater reliability than current wired IP by offering redundant links from multiple towers. III.2. Wireless Data Needs The introduction of 3G increased wireless WAN (Wide Area Network) speeds from 9.6 to 14.4 kbps (less than half of dial-up) to over 60 kbps (twice as fast as dial-up). As far as broadband data speeds, current 3G is no where close. However, with in a few years several enhancements to CDMA2000 and UMTS systems, like EV-DV and HSDPA, will bring broadband like speeds. Even with these two technologies on the roadmap, several issues still exist. Transmitting high speed wireless data over voice-centric cellular technology will have inconveniences that broadband users will not accept. III.2.1. All IP System One of these inconveniences is the inherent latency that is introduced when transmitting data over voice centric air link. 3G technologies such as CDMA2000, EDGE and UMTS need gateways called PDSNs (Packet Data Service Nodes) or SGSMs (Serving GPRS Support Nodes). The basic functions of these gateways are to translate the IP layer of a data packet into a packet that can be transmitted of the voice centric air link. With 2.5G and 3G systems, available voice segments are grouped together to send bursts of data traffic. Essentially, this is not true packet switched data, but grouping open circuit slots for short periods of time. Because of this packet switching emulation, latency is typically 10 or more times greater than on a wired network. On several unnamed GPRS and CDMA2000 networks in the United States, latencies between 300 and 600 milliseconds (over half a second) have been consistently verified. Typical broadband connections provide latencies less than 30 milliseconds. Extra latency creates a perceived decrease in throughput. Each request or task takes a longer time to transmit and receive. Increased latency also decreases the performance of or even prohibit multi-media and corporate applications. Acknowledgement of requests or not sent efficiently in a high latency link. This causes 30
  • 31. longer retransmission times for dropped packets and reducing realized throughput. During peak traffic times, significant delay causes frequent time-outs of web pages and requested data. The easiest way to solve this problem is to have a wireless technology with an IP core and wireless link. An all IP system will allow the IP protocol to be transmitted over the wireless air link, which needs no translation and introduces no latency. Having an IP system is difficult or impossible when data and cellular voice is transmitted over the same carriers. The best solution is to separate wireless traffic onto two links, one for voice and one for broadband. By separating these links, voice networks can maintain their current infrastructure and broadband users can endure the advantages of an all IP system. III.2.2. Dormant States The total number of active users transmitting data over an air link is equal to the number of voice users that can access an air link. When both services are sharing the link, they compete for connection time on the air link. In order to accommodate capacity limits, data users on 3G networks are typically forced into a dormant state after short periods of inactivity. A dormant state means the device still has a connection and does not need to re-log on, but the RF link is inactive and needs to be reconnected in order to make the next data request. This reconnection time is typically about a second, however if the network is temporarily full with voice users, the reconnect time could take much longer. These constant reconnections lead to noticeable delays in the ability to retrieve information and significantly reduce the usefulness of the product. Again, the easiest way to solve this reconnection problem is to create a separate carrier for voice and data users. Voice users tend to access the network frequently for short periods of time. Data users tend to access a network infrequently for longer periods of time. When voice and data users share a wireless link, data users are forced into a dormant state after short periods of time to adhere to the characteristics of a voice traffic network. By separating the data users onto their own link, an operator can maintain a much longer active connection time before forcing data users to go into a dormant state. 31
  • 32. III.3. Why 3G Data? If 3G has these inherent issues, why maintain and develop 3G data? This is simple; there are different wireless data needs and 3G cellular technology fulfills a large percentage of those needs. III.3.1. Phone Integration Current studies repeatedly point to messaging as the most important mobile application. Messaging consist of email, two-way instant messaging and paging. Customers are simply not willing to neither pay the monthly fees for a wireless broadband connection nor carry around larger equipment for something that can be integrated with their phone and included in their cellular bill. Phone integration creates a big need for 3G technology. Cellular phone cost and size would increase dramatically if wireless broadband was integrated with cellular voice technology and implemented with the same phone. Integrated PDA phones, which operate on Palm and Pocket PC operating systems, are becoming common in the market place. These devices can support basic web browsing, access to corporate resources as well as messaging. Each of these applications does not require broadband speeds, nor are they hindered by the same issues that broadband users are. Further PDA phones are on the edge of portability and cost effectiveness, so integrating any additional technology would make an unmarketable product. A similar case can be made for camera phones. The relatively low resolution pictures that camera phones take do not need broadband throughput to transmit. Currently cellular phones do need a packet based wireless transmission technology like 3G to transmit low to medium bandwidth data that emerging applications need. However, cellular phones can not afford the size or cost associated by integrating an additional technology like wireless broadband. III.3.2. Mobile Wireless Data Another reason that 3G data is needed is simple mobility. 3G is designed to work in a completely mobile environment, which includes data transmission over handoffs. 32
  • 33. Wireless broadband technology can be made portable, but many throughput advantages are taken away when it is made mobile. The difference between portable and mobile is that mobile can accommodate continuous data transmission across cellular boundaries. Essentially, both portable and mobile are wireless, but mobile can maintain a connection while moving throughout a network at the sacrifice of capacity and speed. Besides phones and all of its variants, many new devices such high end PDAs, ultra-personal computers and tablet PCs will require mobile connections. Also, there are many vehicular telemetry applications for public safety and transportation that will need a truly mobile connection. III.4. A Compliment to 3G In order to continue growth and maintain profitability, cellular operators should consider deploying a compliment to 3G. This compliment to 3G should be an effective non-LOS wireless broadband technology is capable of providing broadband Internet access. By deploying a compliment to 3G, operators will need to deploy a two-tier wireless network. III.4.1. Two-tier Network Tier one should be based upon a 3G technology with excellent voice capacity and consistent data rates up to 100 kbps. The focus of the 3G network will be to carry voice traffic and data traffic for phones, PDA phones and camera phones. Also, any kind of mobile applications such as vehicle telemetry and data connections for tablet PCs will be ideal for the 3G tier. Tier two should be based upon a wireless broadband technology with enough bandwidth to cover up to a hundred simultaneous active users per cell and burst megabit throughput to individual users. The focus for the wireless broadband network will be to carry data traffic for fixed household and business broadband. The wireless broadband tier will also be ideal for portable broadband and laptop users requiring large bandwidth for corporate or multi-media applications. 33
  • 34. III.4.2. Spectrum Allocation key to Success A down side of a two tier system is that more spectrum is needed to run two different networks. In order for a two tier network to exist, an operator will need to fit both 3G and wireless broadband channels with in their spectrum licenses. Operators will need to study the usage patterns of their customer base in order to create an optimum ratio of 3G carriers to wireless broadband carriers. Narrow carrier technologies will allow operators to have more flexibility in choosing the right ratio of data and voice technologies. Most wireless licenses are designed for FDD technologies and most voice technologies are FDD duplexed. In order for TDD wireless broadband technologies to be deployed with FDD 3G technologies, TDD technologies will have to be deployed in pairs. One TDD carrier can be deployed in the uplink spectrum and the paired TDD carrier can be deployed in the downlink spectrum. Appendix B provides some examples of two tier wireless deployments with in 20 & 30 MHz licenses. Also, each technology needs to have a reuse pattern of one. This will allow carriers to create six sector cells if extra capacity is needed in a dense traffic areas and the operator is spectrum limited. Single reuse patterns also allow carriers to effectively use an antenna enhancement technology and further reuse spectrum within sector boundaries. III.5. Conclusion 3G cellular technology has improved voice capacity over 2G technologies. 3G has also increased data throughput to meet the needs of mobile phone applications including email, paging and micro-browsing. However, 3G is missing out on a killer application, wireless broadband. Less than 10% of the worlds Internet users have broadband access, which creates a tremendous growth and revenue potential. Due to several inadequacies of 3G cellular technology, it can not and will not meet the needs of wireless broadband access. Thus, 3G needs a compliment, and that compliment is non-LOS wireless broadband technology. These technologies are designed to co-locate on existing cellular towers. By reusing existing infrastructure, deployment becomes simple and cost effect for telecom operators. Bottom-line, operators will fulfill more customer needs, create a 34
  • 35. more complete product and thus increase subscribers and revenues all by deploying and implementing a compliment to 3G. 35
  • 36. Appendix A: Compliment to 3G Comparison See Attached Spreadsheet, tab 3G Comp 36
  • 37. Appendix B: Example Deployments See attached spreadsheet, tab Deployment 37
  • 38. Appendix C: Acronyms (Alphabet Soup) 2G NLOS (2nd Generation Non Line Of Site)- refers to newer wireless broadband technologies that replaces LOS systems 3G (3rd Generation)- refers to 3rd generation cellular technology that has data rates capable of 144 kbps 8-PSK (8 Phase Shift Keying)- modulation technique with 8 unique symbols representing 3 bits per symbol (23) 16-QAM (16 Quadrature Amplitude Modulation)- modulation technique with 16 unique symbols representing 4 bits per symbol (24) 32-QAM (32 Quadrature Amplitude Modulation)- modulation technique with 32 unique symbols representing 5 bits per symbol (25) 64-QAM (64 Quadrature Amplitude Modulation)- modulation technique with 64 unique symbols representing 6 bits per symbol (26) ARQ (Automatic Repeat Request)- algorithms designed to optimize packet size for minimal dropped packets BTS (Base Transceiver Station)- the towers in a cellular system CDMA (Code Division Multiple Access)- multiple accessing scheme that spreads and divides users by codes, used in IS-95, CDMA2000 & WCDMA CDMA2000 3rd generation choice for IS-95 operators Codec (coder/ decoder)- describes the chipset in a phone or BTS that converts voice to/from digital bits DL (Down Link)- refers to link going from BTS to handset DSSS (Direct Sequence Spread Spectrum)- similar to CDMA, spreads many narrow band carriers over a wide band carrier EC (Error Control)- code used to control errors in wireless link EDGE (Enhanced Data rates for Global Evolution)- enhancement to GSM which is capable of theoretical data rates up to 473.6 kbps EV-DO (Evolution Data Optimized)- a high data rate enhancement to CDMA2000, does not carry voice traffic 38
  • 39. EV-DV (Evolution Data Voice)- a high data rate enchantment to CDMA2000, carries voice and data traffic FDD (Frequency Division Duplexing)- describes duplexing method with a separate link and channel each for uplink and downlink FEC (Forward Error Control)- code used to control transmission errors on the downlink or forward link of a wireless system FHSS (Frequency Hopped Spread Spectrum)- hopes between narrowband sub frequencies on a wideband frequency to avoid interference GMSK (Gausian Minimum Shift Keying)- modulation technique used in GSM, transmits one bit per symbol GSM (Global System for Mobile communications or Group Special Mobile)- most widely used cellar technology, TDMA based, 200 kHz carriers, 8-16 time slots, 3-4 frequency reuse iDEN (integrated Digital Enhanced Network)- TDMA based technology developed by Motorola for Nextel, 25 kHz carriers, 3-6 time slots, 4-7 frequency reuse IEEE (Institute for Electrical and Electronic Engineers) IP (Internet Protocol)- fundamental information layer of data packets used to transmit over the Internet IS-95 CDMA based cellular technology, 1.25 MHz carriers IS-136 (United States Digital Cellular)- a TDMA based cellular technology used predominately in North America, 30 kHz carriers, 3-6 time slots, 4-7 frequency reuse kbps (kilo bit per second)- data transmission rate of one thousand bits per second kHz (kilo Hertz) one thousand hertz or one thousand times per second LOS (Line Of Site)- describes wireless systems that can only transmit with out obstructions between two transceiver Mbps (Mega bits per second)- data transmission rate of one million bits per second or 1000 kbps MHz (Mega Hertz) one million hertz or one thousand kHz 39
  • 40. MIMO (Multiple Input Multiple Output)- a system of placing multiple antennas on the transmitter and receiver MUD (Multi-User Detection)- a coding enhancement used to detect other users codes and signal to create a cleaner link for a system NLOS (Non LOS)- describes wireless systems that can transmit in environment with obstructions OFDM (Orthogonal Frequency Division Multiplexing)- separates users by frequency tones that are orthogonal PDC (Personal Digital Cellular)- TDMA based technology used in Japan QoS (Quality of Service)- refers to level of service needed to guarantee customer satisfaction QPSK (Quadrature Phase Shift Keying)- modulation technique used in 3rd generation CDMA, represents two bits per symbol RF (Radio Frequency)- describes the electrometric spectrum typically associated with radio transmission SIC (Successive Interference Cancellation)- coding technique used to cancel out other users interference to create a cleaner individual channel TDD (Time Division Duplexing)- describes duplexing method that transmits uplink and downlink simultaneously on a single link TDMA(Time Division Multiple Access)- multiple accessing scheme that separates users by time slots, used in GSM, IS-136, PDC & iDEN TD-SCDMA (Time Division- Synchronous CDMA)- wireless technology with TDD duplexed CDMA air link, typically 1.6 MHz carriers UL (Up Link)- refers to link from the handset to the BTS UMTS (Universal Mobile Telecommunication System)- commercial name for WCDMA WCDMA (Wideband CDMA)- 3rd generation choice for GSM operators, 5 MHz carriers 40
  • 41. Appendix D: References Airvana. “All-IP 1xEV-DO Wireless Data Networks”, Technical White Paper. Bell Mobility. Presentation: “HSDPA and 1xEV-DV Harmonization Opportunities”, November 13-14, 2001. Dornan, Andy. The Essential Guide to Wireless Communications and Applications, second edition. 2002, Prentice Hall. Flarion Technologies. “11 key Design Requirements for a Mobile Broadband Data Network”, January 2002. Flarion Technologies. “Low Latency, The Forgotten Piece of the Mobile Broadband Puzzle”, May 2002. Flarion Technologies. “The benefits of a Packet-Switched All-IP Mobile broadband Network”, September 2002 Goldburg, Marc and Roy, Richard H. “The Impacts of SDMA on PCS System Design”, ArrayComm Inc. Iospan Wireless, “Fixed Broadband Wireless Access: State of the Art, Challenges, and Future Directions”, IEEE Communications Magazine, January 2001. Kuo, Wen-Yi, Wiscom. Presentation: “3G-3.5G WCDMA, Technologies, Markets, Products and the Future” Lindstrom, Annie. “Smart Antenna Advocates Tell Why They Have the Best Solution To Lower Carrier Cost and Improve Network Efficiency”, Broadband Wireless Online, May/ June 2002. Lowery, Eric. “The suitability of OFDM as a modulation technique for wireless telecommunications, with a CDMA comparison”, October 16th, 2001. Martinez-Munoz, Alejandro, “Advantages of AABS Smart Antenna Technology”, Nortel Networks, October1st, 2002. Paulraj, Arogyaswami and Sampath, Hemanth. “Space-time Wireless Communications”, Iospan Wireless, January 2001. Polakos, Paul. “Intelligent Antennas and BLAST for CDMA2000 and WCDMA networks”, Lucent Technologies, 2002. Qualcomm, Inc. “1xEV: 1xEVoluiton IS-856 TIA/EIA Standard, Airlink Overview”, Novemeber 7th, 2001. 41
  • 42. Qualcomm, Inc, Roy Davis, Parag Agashe, Walid Hamdy, Etienne Chaponniere. “Mobile Receive Diversity in CDMA2000”, Simulation and Field Test Results. Rappaport, Theodore S. Wireless Communications. Second edition, Prentice Hall, 2001. Shtrom, Victor. “CDMA vs OFDM in Broadband Wireless Access”, Iospan Wireless, July 2002. Shtrom, Victor and Tellado, Jose. “Turning to MIMO for Non-LOS Wireless Operation”, Contribution to CommsDesign.com, May 2002. Shtrom, Victor. “MIMO Technology: Enabling Second Generation Fixed BWA”, Contribution to WirelessFuture Magazine, March 2002. Telecommunications Online. “The 10 Hottest Technologies”, April 2002. Network Vendor Specifications from product sheets: www.arraycomm.com i-Burst System www.beamreachnetworks.com BeamPlex System www.ericsson.com EDGE & WCDMA www.flarion.com Flash-OFDM www.iospanwireless.com AirBurst Design www.ipwireless.com IPWireless System www.lucent.com BLAST www.navini.com Ripwave System www.nokia.com EDGE & WCDMA www.nortel.com AABS www.qualcomm.com CDMA2000 Communication Organization sites www.3gpp.org Third Generation Project Partnership www.3gpp2.org Third Generation Project Partnership 2 www.bwif.org Broadband Wireless Internet Forum www.cdg.org CDMA Development Group www.IEEE.org IEEE www.ofdm-forum.org OFDM Forum www.tddcoalition.org TDD Coalition www.tiaonline.org Telecommunication Industry Association www.umts-forum.org UMTS Forum www.umtsworld.com UMTS information site www.wow-com.com Cellular Telecommunication Industry Association 42