mansoor2
2008-10-14, 01:24 AM
IP Broadband Access Network Construction – WiMAX
Wu Tao
Specialist, Network Marketing Department
Huawei Technologies Co., Ltd.
Abstract
This article analyzes the technical features and investment potential of the worldwide interoperability for microwave access (WiMAX) technology. It also provides a possible application for its deployment. It is well known that WiMAX is a hot topic. The following are some facts on WiMAX technology:
Institute of Electrical and Electronics Engineers (IEEE) 802.16-2004 was released in July 2004, and IEEE 802.16e was released in February 2006.
The number of WiMAX Forum members has increased to more than 300.
Large telecom operators and telecom equipment suppliers show more concern about WiMAX.
Several consultant firms have predicted the market for WiMAX and analyzed business models based on this technology.
The WiMAX Forum began certifying 16d-compliant equipment at Cetecom Lab in late 2005.
From the above factors, it seems that WiMAX has been widely practiced in the industry, contrary to popular belief. This document also describes the application potential of WiMAX in fixed networks from the technology feature perspective.
Technology Features
As a metropolitan-area network (MAN) wireless-access standard, IEEE 802.16 focuses on defining both the media access control (MAC) and physical layer (PHY) technologies of the air interface and supports broadband Internet protocol (IP) and wireless features. These two technology features are the latest trend of network evolution and are setting a great expectation for the WiMAX application in the telecom industry. The following technology features highlight is IEEE 802.16:
Orthogonal Frequency Division Multiplexing (OFDM)-Based Physical-Layer Technology
IEEE 802.16 defines a wide range of technologies applied at the PHY, which includes the following:
Single-carrier—WirelessMAN-SC and WirelessMAN-SCa
OFDM-based—WirelessMAN-OFDM, which has been included in the WiMAX Forum certification profile
Orthogonal frequency division multiple access (OFDMA)-based—WirelessMAN-OFDMA, which will be incorporated in the WiMAX Forum certification profile of 2006
Unlicensed band—WirelessHUMAN
In other words, WiMAX is a wireless system based on OFDM. As a special multi-carrier transmission solution, OFDM can be deemed as a modulation mode or a multiplex technology. During the multi-carrier transmission, a data stream is segmented into multiple sub-data streams. These sub-data streams are transmitted at a far lower bit rate and are used to modulate sub-carriers. Thus, multiple symbols at a low rate are transmitted concurrently. With OFDM, sub-carriers are orthogonal with one another. After the modulation, spectrums can be overlapped with one another, thus weakening the interference between sub-carriers and improving spectrum utilization. OFDM has the following advantages when compared with the traditional single-carrier technology and CDMA technology:
It resists selective frequency fading or narrowband interference through its multi-carrier feature.
It resists interference between signal waveforms, which enables OFDM to be applied to high-speed data transmission in multipath environment and fading channels.
It resists fading by the united code of all sub-carriers.
These advantages enable OFDM to become the mainstream technology in mobile communications after the third generation. IEEE 802.16 defines a wide range of analog channel bandwidth. Table 1 lists the channel data rates available in different modulation modes under the analog bandwidth condition when OFDM 256 is used.
Modulation Mode
Uncoded Burst Rate (Mbps)
Channel Bandwidth 3.5 MHz 7 MHz 14 MHz 20 MHz QPSK 1/2 2.4 4.8 9.6 13.82 QPSK 3/4 3.6 7.2 14.4 20.74 16 QAM 1/2 4.8 9.6 19.2 27.65s 16 QAM 3/4 7.2 14.4 28.8 41.47 64 QAM 2/3 9.6 19.2 38.4 55.30 64 QAM 3/4 10.8 21.6 43.2 62.21
Table 1 Uncoded Burst Rates for OFDM 256
With WiMAX, the coverage varies with the scenarios. The typical near line of sight (NLOS) coverage includes the following:
Fixed/nomadic application—1 km-10 km
Portable/mobile application—0.5 km-4 km
In summary, the physical feature of WiMAX decides its potential to support metropolitan broadband-wireless access with portable and mobile capability. MAC Scheduling Based on Bandwidth on Demand
The bandwidth-on-demand scheme is as follows: The air interface is a shared medium, which makes the bandwidth allocation scheme complicated. As defined in IEEE 802.16, the upstream and downstream bandwidth is allocated by the burst size (BS) according to the rights of the softswitches (SSs) and its actual requirements. This improves the utilization of channels and supporting transmission of IP packets. In other words, the IEEE 802.16-compliant air interface is designed to realize all-IP access.
The packets from the BS to SSs are transmitted in a point-to-multipoint (PMP) manner, so that the transmission can be considered as a broadcast. The time slots for packet transmission are assigned by the BS.
The packets from SSs to the BS are transmitted in a multipoint-to-point manner, ultimately leading to collision. The MAC scheme of upstream channels defined in IEEE802.16 is based on request. SSs send request messages for time slots to the BS, according to the size of packets to be sent. The BS allocates time slots and broadcasts the allocation information by an uplink map (UL-MAP) message. Only after getting the time slots for itself, SS sends data packets. However, the messages, as well as request ones, sent by SSs for the first time will collide. To avoid such collisions, the MAC scheme provides a collision-detection and random back-off scheme. In general, the mechanism realizes bandwidth on demand to deliver packets with variable length and services with different bandwidth requirements.
In the scenario of a time division duplex (TDD) application, the proportion of upstream bandwidth to downstream bandwidth can be adjusted as required. For example, in the case of a major asymmetric service such as Internet access, the downstream bandwidth is larger than the upstream bandwidth. When the major service is a symmetric service such as voice over IP (VoIP), the upstream and downstream bandwidths are almost the same.
Connection-Oriented Layer-2 QoS-Guarantee Scheme
Quality of service (QoS) at the IEEE 802.16 MAC layer is defined by taking advantage of the mature data over cable service interface specifications (DOCSIS) 1.1 standard of hybrid fiber/coax (HFC) access. On upstream channels, collision usually occurs for request messages. IEEE 802.16 provides a connection-oriented QoS-guarantee scheme. Any packet is transmitted in a service-flow connection. The QoS parameters and bandwidth allocation arithmetic are subject to connection type, thus supporting different types of service provisioning.
For example, suppose an unsolicited grant service (UGS) connection was set up and activated for a VoIP call. In this case, SSs need not send request messages. The BS assigns upstream transmission time slots with a fixed duration at regular intervals for the UGS connection and the QoS approaches that of the time division multiplex (TDM).
Table 2 lists the features of scheduling different traffic as defined in IEEE 802.16 and proves that IEEE 802.16 better supports Layer-2 QoS for broadband services.
Traffic type Traffic feature Application UGS BS assigns time slots with a fixed duration regularly Real-time services with fixed packet size, (i.e., T1/E1, VoIP, asynchronous transfer mode [ATM] leased line) rtPS BS provides time slots for unicast requests regularly Real-time services with flexible packet size (i.e., video) nrtPS BS provides time slots for unicast Requests irregularly Data services requiring high quality (i.e., file transfer protocol [FTP]) BE Best-effort delivery Data services (i.e., hypertext transfer protocol [HTTP] and e-mail]
Table 2 Connection Type Defined in 802.16
Although IEEE 802.16 MAC defines flexible schemes at the MAC layer to assure QoS, the service sensing, QoS authorization, authorization interface, the QoS policy of backbone network, and so on should be taken into consideration to ensure a total network solution for QoS. These are outside the scope of the 802.16 standard.
Customer-Premises Equipment (CPE) Provisioning and Management
Unified-terminal provisioning and management play an important role in supporting large-scale applications. IEEE 802.16 defines the initialization procedure of SSs as follows:
Channel scanning after switching on SSs
Setting up the PHY and MAC-layer connection
Key negotiation
Obtaining IP addresses from the dynamic host configuration protocol (DHCP) server
Getting configuration file from the trivial FTP (TFTP) server
Registration into the BS
Along with management information base (MIB) of SSs defined by 802.16, it enables the possibility of realizing zero-configuration during the service provisioning, centralized management of terminals, and coexistence of terminals manufactured by different vendors. Thus, large-scale applications are facilitated and operation costs are lowered. IP-Based Network Architecture
The IP-based WiMAX network architecture supports an open service platform that provides various services, including bi-directional voice, data, Internet, and video services.
The componentized and IP-based network architecture easily integrates into an existing IP access network, or a MAN, and they enable the sharing of management servers such as authentication and accounting servers and network-management system (NMS) servers. The WiMAX network architecture will be applied in high-speed Internet access, bi-directional data communications, private and public phone, bi-directional media service, broadcast video, and so on.
If operators build their networks in some areas that are short of wired facilities, then the fixed broadband wireless access (FBWA) technology has the following advantages over other technologies:
Quick network deployment and low initial investment
High flexibility of network management
Easy network maintenance and easy device upgrading
Cost Features
In certain models, the WiMAX access network has the following additional features when compared with asymmetric digital subscriber line (ADSL) and fiber-to-the-home (FTTH) access:
Important terminal costs—With WiMAX, one BS cost is shared by multiple SSs. Therefore, the cost of the SS becomes more important than the cost of the BS. Reducing the cost of constructing a WiMAX access network would reduce the cost of SSs.
Cost advantage in a dispersive scenario—In a scenario with many users, ADSL has better cost advantage, but in a dispersive scenario, WiMAX is more cost-effective.
Close association between average cost per line and service—Especially when services requiring high bandwidth are provisioned, including large-bandwidth leased-line service and video service, the number of supported SSs is small and the average cost per line is high.
Potential Applications
WiMAX might have a great potential in the following applications: Networking of the Backhaul Application
Ethernet interfaces and E1/T1 interfaces should be provided to realize DSL access multiplexer (DSLAM)/multiservice access node (MSAN)/cellular BS access in the areas where it is difficult to deploy fiber. The IEEE 802.16-based system can provide a good QoS assurance and bears both E1/T1 and Ethernet signals by different connections. On a single channel with the emulation bandwidth of 20 MHz, the data rate can reach 20 Mbps-60 Mbps (16 quadrature amplitude modulation [QAM]/64 QAM). Thus, the networking of a backhaul application can be implemented when the total bandwidth requirements are within a certain range, including applications in point-to-point (PTP) and PMP scenarios.
http://www.iec.org/newsletter/oct06_1/imgs/analyst_fig_1.gif Figure 1 Backhaul Application
Interconnection between Headquarters and Branches
To implement interconnection between the headquarters and branches, WiMAX should enable an application similar to leased lines and assure virtual private network (VPN) isolation and QoS at the access layer.
http://www.iec.org/newsletter/oct06_1/imgs/analyst_fig_2.gif Figure 2 Interconnection for Business Application
Small-to-Medium Enterprise (SME)/Server Message Block (SMB) Access
Using WiMAX, start-up operators can speed up service development and traditional operators can set up SME/SMB access in the areas without fiber/cable deployment. The SME/SMB access will be a major application at the initiation phase of the WiMAX market because operators can bear the high costs of SME/SMB access.
There are two scenarios for SME/SMB access:
Data + VoIP
Data + TDM Voice
For details, refer to Figure 3.
http://www.iec.org/newsletter/oct06_1/imgs/analyst_fig_3.gif Figure 3 SME/SMB Broadband Access Application
To implement SME/SMB access, pay more attention to the following:
IP address planning and allocation—Recommend planning IP subnets that follow different types of service terminals. The SSs defined in IEEE 802.16 support DHCP Option60. Thus, IP addresses of subnets can be allocated to terminals of different types during the DHCP application.
Security and isolation—By setting virtual local-area networks (VLANs) in different manners, execute various security and isolation measures as required.
QoS assurance—The system compliant with IEEE 802.16 can provide different connection types and priorities for VoIP and TDM services. Pay more attention to assure dynamic QoS in VoIP service to achieve optimal balance between voice quality and channel utilization.
TDM (E1) transmission—The demand for TDM voice capacity in SME/SMB access is low. So, the system must support the transmission of fragmented E1.
Residential Broadband Access
By using WiMAX, start-up operators can speed up broadband services, and the traditional operators can provide residential broadband access in the areas without twisted-pair deployment.
http://www.iec.org/newsletter/oct06_1/imgs/analyst_fig_4.gif Figure 4 Residential Access Application
The following are some of the key points in the application of residential broadband access:
Seamless integration with fixed networks—As an IP-based access network technology, WiMAX can be integrated to existing fixed networks seamlessly.
Terminal form—Several forms are supported, including all-outdoor SS, all-indoor SS, home gateway with WiMAX uplink, SS with embedded wireless fidelity (Wi-Fi), and SS with embedded integrated access device (IAD).
Service-supported—As described above, the WiMAX cost is sensitive to the bandwidth demand. Thus, the major services are data and VoIP, and the minor service is video.
Automatic configuration and integrated management of terminals—The system compliant with IEEE 802.16 makes automatic configuration and integrated management of terminals possible.
Subscriber authentication—Broadband access subscribers can perform authentication following the approach to DSL-access subscriber authentication, including PTP protocol over Ethernet (PPPoE) and Web authentication. For IAD service, DHCP + authentication mode can be used.
QoS—IEEE 802.16 provides Layer-2 support for QoS assurance of various services. Dynamic end-to-end QoS of VoIP service should also be considered.
Wi-Fi Backhaul
In a PMP scenario, WiMAX enables the coverage of a 1 km-10 km distance. Thus, WiMAX is suitable for Wi-Fi backhaul. With WiMAX, the application of Wi-Fi can expand.
Portable/Low-Speed Mobile Access
The mobile network will evolve to OFDM- and IP-based architecture and WiMAX enables OFDM and IP-based architecture.
The WiMAX Forum Network Working Group is now defining the standard of the whole access network based on IEEE 802.16 to support applications of fixed, nomadic, portable, and low-speed mobile access. These applications provide data, information management system (IMS), voice, and video services, and enable interworking among ADSL, cable, Wi-Fi, third generation (3G), and next-generation networks (NGN).
Fixed-Mobile Convergence (FMC) Solution
Another potential application of WiMAX is the FMC solution, which combines the features of portable/low-speed mobile access and also makes use of the existing wired network of fixed network operators. For example, by using WiMAX/Wi-Fi dual-mode terminals, subscribers can switch between WiMAX hot zones and Wi-Fi hot spots, or between WiMAX hot zones and home ADSL + Wi-Fi. This allows the subscribers to balance the service experience and costs.
From the above analysis, we can see that WiMAX not only solves realistic problems for operators—including providing backhaul, SME/SMB access, and residential access applications in areas where fiber and coaxial cables are difficult to reach—but also has the potential ability to offer more attractive and more competitive services to the subscriber.
Wu Tao
Specialist, Network Marketing Department
Huawei Technologies Co., Ltd.
Abstract
This article analyzes the technical features and investment potential of the worldwide interoperability for microwave access (WiMAX) technology. It also provides a possible application for its deployment. It is well known that WiMAX is a hot topic. The following are some facts on WiMAX technology:
Institute of Electrical and Electronics Engineers (IEEE) 802.16-2004 was released in July 2004, and IEEE 802.16e was released in February 2006.
The number of WiMAX Forum members has increased to more than 300.
Large telecom operators and telecom equipment suppliers show more concern about WiMAX.
Several consultant firms have predicted the market for WiMAX and analyzed business models based on this technology.
The WiMAX Forum began certifying 16d-compliant equipment at Cetecom Lab in late 2005.
From the above factors, it seems that WiMAX has been widely practiced in the industry, contrary to popular belief. This document also describes the application potential of WiMAX in fixed networks from the technology feature perspective.
Technology Features
As a metropolitan-area network (MAN) wireless-access standard, IEEE 802.16 focuses on defining both the media access control (MAC) and physical layer (PHY) technologies of the air interface and supports broadband Internet protocol (IP) and wireless features. These two technology features are the latest trend of network evolution and are setting a great expectation for the WiMAX application in the telecom industry. The following technology features highlight is IEEE 802.16:
Orthogonal Frequency Division Multiplexing (OFDM)-Based Physical-Layer Technology
IEEE 802.16 defines a wide range of technologies applied at the PHY, which includes the following:
Single-carrier—WirelessMAN-SC and WirelessMAN-SCa
OFDM-based—WirelessMAN-OFDM, which has been included in the WiMAX Forum certification profile
Orthogonal frequency division multiple access (OFDMA)-based—WirelessMAN-OFDMA, which will be incorporated in the WiMAX Forum certification profile of 2006
Unlicensed band—WirelessHUMAN
In other words, WiMAX is a wireless system based on OFDM. As a special multi-carrier transmission solution, OFDM can be deemed as a modulation mode or a multiplex technology. During the multi-carrier transmission, a data stream is segmented into multiple sub-data streams. These sub-data streams are transmitted at a far lower bit rate and are used to modulate sub-carriers. Thus, multiple symbols at a low rate are transmitted concurrently. With OFDM, sub-carriers are orthogonal with one another. After the modulation, spectrums can be overlapped with one another, thus weakening the interference between sub-carriers and improving spectrum utilization. OFDM has the following advantages when compared with the traditional single-carrier technology and CDMA technology:
It resists selective frequency fading or narrowband interference through its multi-carrier feature.
It resists interference between signal waveforms, which enables OFDM to be applied to high-speed data transmission in multipath environment and fading channels.
It resists fading by the united code of all sub-carriers.
These advantages enable OFDM to become the mainstream technology in mobile communications after the third generation. IEEE 802.16 defines a wide range of analog channel bandwidth. Table 1 lists the channel data rates available in different modulation modes under the analog bandwidth condition when OFDM 256 is used.
Modulation Mode
Uncoded Burst Rate (Mbps)
Channel Bandwidth 3.5 MHz 7 MHz 14 MHz 20 MHz QPSK 1/2 2.4 4.8 9.6 13.82 QPSK 3/4 3.6 7.2 14.4 20.74 16 QAM 1/2 4.8 9.6 19.2 27.65s 16 QAM 3/4 7.2 14.4 28.8 41.47 64 QAM 2/3 9.6 19.2 38.4 55.30 64 QAM 3/4 10.8 21.6 43.2 62.21
Table 1 Uncoded Burst Rates for OFDM 256
With WiMAX, the coverage varies with the scenarios. The typical near line of sight (NLOS) coverage includes the following:
Fixed/nomadic application—1 km-10 km
Portable/mobile application—0.5 km-4 km
In summary, the physical feature of WiMAX decides its potential to support metropolitan broadband-wireless access with portable and mobile capability. MAC Scheduling Based on Bandwidth on Demand
The bandwidth-on-demand scheme is as follows: The air interface is a shared medium, which makes the bandwidth allocation scheme complicated. As defined in IEEE 802.16, the upstream and downstream bandwidth is allocated by the burst size (BS) according to the rights of the softswitches (SSs) and its actual requirements. This improves the utilization of channels and supporting transmission of IP packets. In other words, the IEEE 802.16-compliant air interface is designed to realize all-IP access.
The packets from the BS to SSs are transmitted in a point-to-multipoint (PMP) manner, so that the transmission can be considered as a broadcast. The time slots for packet transmission are assigned by the BS.
The packets from SSs to the BS are transmitted in a multipoint-to-point manner, ultimately leading to collision. The MAC scheme of upstream channels defined in IEEE802.16 is based on request. SSs send request messages for time slots to the BS, according to the size of packets to be sent. The BS allocates time slots and broadcasts the allocation information by an uplink map (UL-MAP) message. Only after getting the time slots for itself, SS sends data packets. However, the messages, as well as request ones, sent by SSs for the first time will collide. To avoid such collisions, the MAC scheme provides a collision-detection and random back-off scheme. In general, the mechanism realizes bandwidth on demand to deliver packets with variable length and services with different bandwidth requirements.
In the scenario of a time division duplex (TDD) application, the proportion of upstream bandwidth to downstream bandwidth can be adjusted as required. For example, in the case of a major asymmetric service such as Internet access, the downstream bandwidth is larger than the upstream bandwidth. When the major service is a symmetric service such as voice over IP (VoIP), the upstream and downstream bandwidths are almost the same.
Connection-Oriented Layer-2 QoS-Guarantee Scheme
Quality of service (QoS) at the IEEE 802.16 MAC layer is defined by taking advantage of the mature data over cable service interface specifications (DOCSIS) 1.1 standard of hybrid fiber/coax (HFC) access. On upstream channels, collision usually occurs for request messages. IEEE 802.16 provides a connection-oriented QoS-guarantee scheme. Any packet is transmitted in a service-flow connection. The QoS parameters and bandwidth allocation arithmetic are subject to connection type, thus supporting different types of service provisioning.
For example, suppose an unsolicited grant service (UGS) connection was set up and activated for a VoIP call. In this case, SSs need not send request messages. The BS assigns upstream transmission time slots with a fixed duration at regular intervals for the UGS connection and the QoS approaches that of the time division multiplex (TDM).
Table 2 lists the features of scheduling different traffic as defined in IEEE 802.16 and proves that IEEE 802.16 better supports Layer-2 QoS for broadband services.
Traffic type Traffic feature Application UGS BS assigns time slots with a fixed duration regularly Real-time services with fixed packet size, (i.e., T1/E1, VoIP, asynchronous transfer mode [ATM] leased line) rtPS BS provides time slots for unicast requests regularly Real-time services with flexible packet size (i.e., video) nrtPS BS provides time slots for unicast Requests irregularly Data services requiring high quality (i.e., file transfer protocol [FTP]) BE Best-effort delivery Data services (i.e., hypertext transfer protocol [HTTP] and e-mail]
Table 2 Connection Type Defined in 802.16
Although IEEE 802.16 MAC defines flexible schemes at the MAC layer to assure QoS, the service sensing, QoS authorization, authorization interface, the QoS policy of backbone network, and so on should be taken into consideration to ensure a total network solution for QoS. These are outside the scope of the 802.16 standard.
Customer-Premises Equipment (CPE) Provisioning and Management
Unified-terminal provisioning and management play an important role in supporting large-scale applications. IEEE 802.16 defines the initialization procedure of SSs as follows:
Channel scanning after switching on SSs
Setting up the PHY and MAC-layer connection
Key negotiation
Obtaining IP addresses from the dynamic host configuration protocol (DHCP) server
Getting configuration file from the trivial FTP (TFTP) server
Registration into the BS
Along with management information base (MIB) of SSs defined by 802.16, it enables the possibility of realizing zero-configuration during the service provisioning, centralized management of terminals, and coexistence of terminals manufactured by different vendors. Thus, large-scale applications are facilitated and operation costs are lowered. IP-Based Network Architecture
The IP-based WiMAX network architecture supports an open service platform that provides various services, including bi-directional voice, data, Internet, and video services.
The componentized and IP-based network architecture easily integrates into an existing IP access network, or a MAN, and they enable the sharing of management servers such as authentication and accounting servers and network-management system (NMS) servers. The WiMAX network architecture will be applied in high-speed Internet access, bi-directional data communications, private and public phone, bi-directional media service, broadcast video, and so on.
If operators build their networks in some areas that are short of wired facilities, then the fixed broadband wireless access (FBWA) technology has the following advantages over other technologies:
Quick network deployment and low initial investment
High flexibility of network management
Easy network maintenance and easy device upgrading
Cost Features
In certain models, the WiMAX access network has the following additional features when compared with asymmetric digital subscriber line (ADSL) and fiber-to-the-home (FTTH) access:
Important terminal costs—With WiMAX, one BS cost is shared by multiple SSs. Therefore, the cost of the SS becomes more important than the cost of the BS. Reducing the cost of constructing a WiMAX access network would reduce the cost of SSs.
Cost advantage in a dispersive scenario—In a scenario with many users, ADSL has better cost advantage, but in a dispersive scenario, WiMAX is more cost-effective.
Close association between average cost per line and service—Especially when services requiring high bandwidth are provisioned, including large-bandwidth leased-line service and video service, the number of supported SSs is small and the average cost per line is high.
Potential Applications
WiMAX might have a great potential in the following applications: Networking of the Backhaul Application
Ethernet interfaces and E1/T1 interfaces should be provided to realize DSL access multiplexer (DSLAM)/multiservice access node (MSAN)/cellular BS access in the areas where it is difficult to deploy fiber. The IEEE 802.16-based system can provide a good QoS assurance and bears both E1/T1 and Ethernet signals by different connections. On a single channel with the emulation bandwidth of 20 MHz, the data rate can reach 20 Mbps-60 Mbps (16 quadrature amplitude modulation [QAM]/64 QAM). Thus, the networking of a backhaul application can be implemented when the total bandwidth requirements are within a certain range, including applications in point-to-point (PTP) and PMP scenarios.
http://www.iec.org/newsletter/oct06_1/imgs/analyst_fig_1.gif Figure 1 Backhaul Application
Interconnection between Headquarters and Branches
To implement interconnection between the headquarters and branches, WiMAX should enable an application similar to leased lines and assure virtual private network (VPN) isolation and QoS at the access layer.
http://www.iec.org/newsletter/oct06_1/imgs/analyst_fig_2.gif Figure 2 Interconnection for Business Application
Small-to-Medium Enterprise (SME)/Server Message Block (SMB) Access
Using WiMAX, start-up operators can speed up service development and traditional operators can set up SME/SMB access in the areas without fiber/cable deployment. The SME/SMB access will be a major application at the initiation phase of the WiMAX market because operators can bear the high costs of SME/SMB access.
There are two scenarios for SME/SMB access:
Data + VoIP
Data + TDM Voice
For details, refer to Figure 3.
http://www.iec.org/newsletter/oct06_1/imgs/analyst_fig_3.gif Figure 3 SME/SMB Broadband Access Application
To implement SME/SMB access, pay more attention to the following:
IP address planning and allocation—Recommend planning IP subnets that follow different types of service terminals. The SSs defined in IEEE 802.16 support DHCP Option60. Thus, IP addresses of subnets can be allocated to terminals of different types during the DHCP application.
Security and isolation—By setting virtual local-area networks (VLANs) in different manners, execute various security and isolation measures as required.
QoS assurance—The system compliant with IEEE 802.16 can provide different connection types and priorities for VoIP and TDM services. Pay more attention to assure dynamic QoS in VoIP service to achieve optimal balance between voice quality and channel utilization.
TDM (E1) transmission—The demand for TDM voice capacity in SME/SMB access is low. So, the system must support the transmission of fragmented E1.
Residential Broadband Access
By using WiMAX, start-up operators can speed up broadband services, and the traditional operators can provide residential broadband access in the areas without twisted-pair deployment.
http://www.iec.org/newsletter/oct06_1/imgs/analyst_fig_4.gif Figure 4 Residential Access Application
The following are some of the key points in the application of residential broadband access:
Seamless integration with fixed networks—As an IP-based access network technology, WiMAX can be integrated to existing fixed networks seamlessly.
Terminal form—Several forms are supported, including all-outdoor SS, all-indoor SS, home gateway with WiMAX uplink, SS with embedded wireless fidelity (Wi-Fi), and SS with embedded integrated access device (IAD).
Service-supported—As described above, the WiMAX cost is sensitive to the bandwidth demand. Thus, the major services are data and VoIP, and the minor service is video.
Automatic configuration and integrated management of terminals—The system compliant with IEEE 802.16 makes automatic configuration and integrated management of terminals possible.
Subscriber authentication—Broadband access subscribers can perform authentication following the approach to DSL-access subscriber authentication, including PTP protocol over Ethernet (PPPoE) and Web authentication. For IAD service, DHCP + authentication mode can be used.
QoS—IEEE 802.16 provides Layer-2 support for QoS assurance of various services. Dynamic end-to-end QoS of VoIP service should also be considered.
Wi-Fi Backhaul
In a PMP scenario, WiMAX enables the coverage of a 1 km-10 km distance. Thus, WiMAX is suitable for Wi-Fi backhaul. With WiMAX, the application of Wi-Fi can expand.
Portable/Low-Speed Mobile Access
The mobile network will evolve to OFDM- and IP-based architecture and WiMAX enables OFDM and IP-based architecture.
The WiMAX Forum Network Working Group is now defining the standard of the whole access network based on IEEE 802.16 to support applications of fixed, nomadic, portable, and low-speed mobile access. These applications provide data, information management system (IMS), voice, and video services, and enable interworking among ADSL, cable, Wi-Fi, third generation (3G), and next-generation networks (NGN).
Fixed-Mobile Convergence (FMC) Solution
Another potential application of WiMAX is the FMC solution, which combines the features of portable/low-speed mobile access and also makes use of the existing wired network of fixed network operators. For example, by using WiMAX/Wi-Fi dual-mode terminals, subscribers can switch between WiMAX hot zones and Wi-Fi hot spots, or between WiMAX hot zones and home ADSL + Wi-Fi. This allows the subscribers to balance the service experience and costs.
From the above analysis, we can see that WiMAX not only solves realistic problems for operators—including providing backhaul, SME/SMB access, and residential access applications in areas where fiber and coaxial cables are difficult to reach—but also has the potential ability to offer more attractive and more competitive services to the subscriber.