Why Wait for Data?
By Jeffrey Belk
While voice remains the dominant revenue stream in wireless communications, data is becoming a service for targeting new markets, adding additional revenue streams and differentiating service offerings, all of which is causing operators to ask themselves a number of questions. How is your network set to handle the increased demands of future services, such as data messaging, information or Internet services, and the eventual requests for graphics, images and video? Do you go through second-generation upgrades or wait for third generation? Are second-generation upgrades an evolution to third generation or do they take you down a divergent path?
The total number of wireless subscribers worldwide is expected to quadruple over the next two to three years, while total wireless minutes-of-use will multiply even faster. Operators will need the flexibility to expand their network capacity to meet increased demand in a cost-effective manner. In addition, a market is emerging for high-speed data services, including Internet access, file transfers and other multimedia applications.
cdmaOne is growing fast. By the time third generation systems are ready for commercial deployment, the total number of cdmaOne subscribers is expected to have risen from today’s 30 million to more than 100 million. Current cdmaOne networks offer excellent voice quality, high capacity and advanced low-speed data services, while providing a clear migration path to even faster and more efficient data services in the near term. Today’s networks support Internet applications like e-mail, web browsing and access to corporate intranets, as well as digital fax and other ‘mobile office’ functions at speeds up to 14.4 kbps. The evolution of cdmaOne networks to support CDMA2000 Phase One capabilities provides for enhanced network performance in a number of areas, including speed and efficiency of data transmission.
In today’s wireless market, CDMA voice and data services are provided with TIA/EIA-95-A infrastructure and subscriber equipment. cdmaOne networks provide both packet and circuit switched data services at speeds up to 14.4 kbps along with a choice of 8K, 13K and 8K EVRC voice services from the same platform. Parts of the world have recently deployed TIA/EIA-95-B systems which offer data speeds up to 64 kbps. This feature is one of the primary benefits of cdmaOne network design—operators don’t have to make significant investments to add low- and medium-rate data services to existing voice capabilities. Typical circuit switched applications include both analog and digital fax and file transfers, while Internet connections and e-mail delivery are popular packet-based applications.
That’s what’s available today. The voice and data requirements for tomorrow are higher capacities, increased spectral efficiency, higher speeds and additional services. CDMA2000 Phase One and High Data Rate (HDR) technology are complementary new technology developments that offer just that.
As the first part of the development and standards effort for 3G CDMA, CDMA2000 Phase One gives operators the ability to double the capacity, or spectral efficiency, of current cdmaOne networks. While CDMA is already the fastest-growing technology in the world for delivering wireless voice services, CDMA2000 Phase One expands capabilities even further to allow packet and circuit data services at speeds up to 144 kbps. The spectral efficiency of CDMA2000 Phase One capable networks allows for an easier, more cost-effective rollout than other technology alternatives.
With Qualcomm’s HDR technology, extremely high data speeds can be offered while valuable radio spectrum is preserved. cdmaOne operators who want to offer peak data rates up to 2.4 Mbps, or who want to offer data services to a large number of customers without diminishing their capacity for voice, will soon be able to implement this data feature on their existing cdmaOne networks. Utilizing a standard-band 1.25 MHz carrier, this solution can be added to existing networks and is optimized to offer peak speeds up to 2.4 Mbps. Qualcomm first publicly demonstrated HDR in September 1998, and field trials are currently underway with U S West and Cisco Systems.
HDR is designed with a goal of being highly compatible with existing cdmaOne systems possessing the same radio frequency (RF) characteristics as cdmaOne, therefore allowing existing CDMA operators to make evolutionary changes to their systems and to preserve their current investments. Furthermore, HDR leverages from IS-95 RF components.
HDR is also a viable and economic solution for rollout of high-speed data to broad geographic areas compared to cable modem, ADSL, ISDN and other wireline data solutions. It can work with an operator’s existing voice system or as a stand-alone system. Spectral efficiency is a key requirement for wireless data services, and HDR is highly spectrally efficient, as it utilizes a single 1.25 MHz band and is able to achieve data rates and performance levels comparable to those of next-generation technologies. The design is centered on optimizing packet data services. It decouples data services from voice service, based on the recognition that the two services have fundamentally different requirements.
Voice services are delay-sensitive and aim to provide equal service to all users, regardless of their location in the cell. These features result in power-sharing schemes, where weaker users are allocated more power than stronger users, which is the optimal solution for voice. A relatively modest data rate is sufficient for high-quality voice service and voice users cannot substantially benefit from higher data rates.
Packet data systems are aimed at maximizing the sector throughput. Given that different data users have various data rate requirements, the goal is no longer to serve everyone with equal power and equal grade of service. Rather, the goal is to allocate users the maximum data rate that each can accept based on application needs and wireless channel conditions.
Features such as ‘dormant mode’ allow the HDR user to go into a dormancy state with a packet data call (i.e., maintain dynamic IP address identity, but not utilize any airlink resources). During dormancy, the user is able to place voice calls on a separate IS-95 CDMA carrier. Once the voice call is completed, the user ends dormancy by sending or receiving HDR packet data. This optimizing feature is known as ‘alternate voice and data’ and allows the user the most efficient use of bandwidth.
HDR’s Internet Protocol (IP)-based architecture is simplified and does not require a large switching system. The network includes standard components such as Cisco routers which allow for easy and cost-effective deployments and installations. The system’s elegant architecture delivers high-performance packet data services with minimal network resources. HDR’s network elements communicate via a standard IP stack, and therefore provide support for mainstream software applications and operating systems. As current cdmaOne systems continue to experience dramatic user growth and increased user demand for higher data rate services, operators will benefit from seamless migration path options such as CDMA2000 Phase One and HDR, that give operators choices for implementing an air interface that can improve capacity and increase data speeds