Don joined Award Solutions in 2005, bringing his knowledge and experience in mobile wireless technologies to bear in the planning, development and delivery of technical training seminars. Don specializes in wireless telecommunications networks, focusing on air interface and core network standards, wireless and Internet applications, and advanced wireless network solutions, such as ad hoc and mesh networking.Don has over 30 years of hands-on experience in the telecommunications and wireless industries. He began his career in Ottawa, Canada, with Nortel Networks (then Bell-Northern Research) as a call processing software designer. He moved to Richardson, Texas, in 1983, as one of the initial team responsible for designing and developing Nortel’s wireless product line. He rose quickly through the ranks, first as a development manager, then as a senior project manager, and then as a director of advanced wireless technology, involved in all aspects of the design of Nortel’s AMPS, TDMA and CDMA products. In his final role at Nortel, Don was responsible for a small technology group investigating advanced networking technologies, including self-organizing wireless mesh networks.Don is currently involved in developing and delivering courses for Award’s 4G (LTE) technology curriculum at many leading telecommunications companies. In addition to technology classes, Don conducts network planning and evolution sessions for large wireless service providers to help RF and core network engineers understand and plan for upcoming technology changes and enhancements such as VoLTE and LTE Advanced.Don received his Bachelor of Science degree in Computer Science (First Class Honors) from the University of British Columbia in Vancouver, Canada. He holds 9 patents in various areas of wireless technology.
By Don Hanley, Senior Consultant - 2/2009
As 4G technologies like Mobile WiMAX and Long Term Evolution (LTE) move closer to commercial reality, operators are beginning to understand the differences and the similarities between what they have currently deployed and what is coming down the road. Service providers who are contemplating the transition from 1xEV-DO to LTE will have to contend not only with new radio technologies and new network architectures, but with a whole new set of terms and concepts as well.
Both 1xEV-DO and LTE are designed to offer high-speed packet data services to mobile subscribers, so it should not be surprising that they have taken similar approaches to solving some of the challenges they both face. An engineer familiar with 1xEV-DO can get a head start with understanding LTE simply by learning the meaning of key LTE terms and associating them with their 1xEV-DO counterparts.
The following sections take various LTE concepts, grouped into related categories, and provide a brief explanation of each, along with the corresponding 1xEV-DO equivalent. In some cases, there is a one-to-one match between LTE and 1xEV-DO; in others, there simply is no equivalent concept. In most cases, however, there is generally something within 1xEV-DO that does the same thing as its LTE counterpart, under a different name or in a different location. We will identify the similarities and differences of LTE-EPC and 1x/1xEV-DO networks in various categories, including Air Interface, Access and Core Networks, Identities and Operations.
LTE is an evolution of the UMTS system defined by the 3G Partnership Project (3GPP), which is an offshoot of the European Telecommunications Standards Institute (ETSI). 1xEV-DO, on the other hand, is designed by the 3G Partnership Project 2 (3GPP2), which is associated with the North American Telecommunications Industry Association (TIA). Both 3GPP and 3GPP2 have mandates to develop specifications for wireless networks, but they have adopted rather different design philosophies, which are reflected in the resulting standards:
Despite the different mindsets behind the specifications, however, both 1xEV-DO and LTE do what they were designed to do quite well: deliver high-speed packet data to mobile users.
Not surprisingly, the greatest differences between LTE and 1xEV-DO lie in the air interface. 1xEV-DO is a CDMA-based system, using fixed 1.25 MHz channels, while LTE is a scalable OFDMA system, capable of using anywhere between 1.4 MHz and 20 MHz, divided into 15 kHz subcarriers. 1xEV-DO devices are assigned timeslots for downlink traffic, but can transmit at any time on the uplink (the hallmark of a CDMA system); LTE terminals must be explicitly allocated uplink and downlink non-overlapping resources to send and receive traffic. The Physical Layer descriptions of these two technologies are as different as night and day.
Nonetheless, they must both be capable of supporting multiple users simultaneously, of allowing new users to access the network, of tracking the terminal's location and redirecting traffic as the user moves. Key LTE terms relating to the air interface, and their 1xEV-DO equivalents, are listed here.
Meaning and Usage
Orthogonal Frequency Division Multiple Access, physical layer of LTE Downlink
Single Carrier Frequency Division Multiple Access, physical layer of LTE Uplink
A single 15 kHz radio channel
A single 66.67 µs time period
Chip (0.81 µs)
The smallest unit of radio resources, one subcarrier for one symbol
The smallest block of resources that can be allocated, 12 subcarriers for 7 symbols (84 resource elements)
7 consecutive symbols1
2 consecutive timeslots
10 consecutive subframes, the basic transmission interval
Periodic signal for synchronizing with and identifying cells
Periodic signal for transmission quality measurements
Physical Broadcast Channel
Physical Downlink Shared Channel
Forward Traffic Channel
Physical Downlink Control Channel
Preambles + MAC channels
Physical Control Format Indicator Channel
Physical Hybrid ARQ Indication Channel
Physical Random Access Channel
Physical Uplink Shared Channel
Reverse Traffic Channel
Physical Uplink Control Channel
Figure 1 illustrates an LTE eUTRAN, the radio access network. The eUTRAN has a flat architecture, with no centralized controller; instead each eNode B manages its own radio resources, and collaborates with other eNode B's over the X2 interface. The eNode B's connect to the core network over the S1 interface, to allow users to register with the network and send and receive traffic.
Key LTE terms relating to the access network, and their 1xEV-DO equivalents, are listed here:
Evolved Universal Terrestrial Radio Access Network
Evolved Node B
Base station + RNC
Physical Layer Cell ID
Unique cell identifier
Pilot PN offset
eNode B <-> eNode B interface
eNode B <-> core network interface
LTE air interface
Specified per 3GPP2 C.S0024 (IS-856)
A configured signaling path between the UE and the eNode B
A configured and assigned radio resource
The LTE and 1xEV-DO core networks are more similar than they are different; Figure 2 shows a view of the LTE Evolved Packet Core (EPC). Both are based on IP protocols, and support seamless access to packet-based services; both make use of Mobile IP to redirect traffic as the user moves through the network.
Key LTE terms associated with the core network, and their 1xEV-DO equivalents, are listed here:
Evolved Packet Core
Packet Data Network
Mobility Management Entity
RNC + PDSN + AN-AAA
PDSN + PCF
Packet Data Network Gateway
Home Subscriber System
Policy Charging Rule Function
A configured traffic path between the eNode B and the S-GW
A10 + R-P Session
A configured traffic path between the S-GW and the PDN-GW
EPS Bearer Service
A configured end-to-end traffic path between the UE and the PDN-GW (Radio Bearer + S1 Bearer + S5/S8 Bearer)
PPP + MIP
When a mobile device arrives in the network, it must be recognized, configured and assigned resources, and its services must be maintained as it moves from cell to cell. Various terms associated with LTE operational functions, and their 1xEV-DO equivalents, are listed here:
User Equipment (the mobile device)
Access Terminal (AT)
International Mobile Subscriber Identity
IMSI [Mobile Country Code (MCC), Mobile Network Code (MNC) and Mobile Identification Number (MIN) or
Mobile Directory Number (MDN)]
International Mobile Equipment Identity
Mobile Serial Number (MSN) or Mobile Equipment Identity (MEID)
Transmissions from the network to the mobile
Forward Link (FL)
Transmissions from the mobile to the network
Reverse Link (RL)
Initial registration process
UATI Assignment + DO Session Establishment + MIP Registration
Master Information Block and System Information Block
Quick Config + Sector Parameters + Access Parameters + DO Session
Downlink Control Information and Uplink Control Information
Traffic Channel Assignment
Cell Radio Network Temporary Identifier
Channel Quality Indicator
Redirection of traffic from one base station to another
Measurement Control events A1, A2, A3, A4, A5, B1, B2
Thresholds for cell selection and handover
Pilot Add, Pilot Drop, Dynamic (Soft Slope) Thresholds
A simple description in a table does not convey the full complexity of a concept; a detailed understanding of LTE's technologies, architectures and interfaces is needed to fully appreciate both the similarities and the differences it has with 1xEV-DO. Nevertheless, the fact that LTE and 1xEV-DO concepts can be laid out side-by-side in this way should help to reassure 1xEV-DO operators that the step from 3G to 4G is not as big a leap as they may have thought.
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The 3GPP and LTE logos are the property of Third Generation Partnership Project (3GPP). The 3GPP2 logo is property of Third Generation Partnership Project (3GPP2) and its organization partners. The TIA logo is property of Telecommunications Industry Association (TIA). The content of this document is based on 3GPP/LTE, 3GPP2 and TIA specifications which are available at www.3gpp.org, www.3gpp2.org, and www.tiaonline.org.