`Department of Electrical and Communications Engineering
`Communications Laboratory
`
`Mohammad Azizul Hasan
`
`Performance Evaluation of
`WiMAX/IEEE 802.16 OFDM Physical
`Layer
`
`Thesis submitted in partial fulfillment of the requirements for the degree of
`Master of Science in Technology, Espoo, June 2007
`
`Supervisor: Prof. Riku Jäntti
`
`Instructor: Lic. Tech. Boris Makarevitch
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 1 of 16
`
`
`
`HELSINKI UNIVERSITY OF TECHNOLOGY
`
`Abstract of the Master’s Thesis
`
`Author: Mohammad Azizul Hasan
`
`Name of the Thesis:
`Performance Evaluation of WiMAX/IEEE 802.16 OFDM Physical Layer
`
`Number of
`pages:
` 96
`
`Date: 08(cid:173)06(cid:173)2007
`
`Department: Department of Electrical and Communications Engineering
`
`Professorship: S(cid:173)72 Communications Engineering
`
`Supervisor: Prof. Riku Jäntti
`
`Instructor: Lic. Tech. Boris Makarevitch
`
`Abstract
`
`Fixed Broadband Wireless Access (BWA) is a promising technology
`which can offer high speed voice, video and data service up to the
`customer end. Due to the absence of any standard specification, earlier
`BWA systems were based on proprietary standard. IEEE 802.16
`WirelessMAN standard specifies a Medium Access Control (MAC) layer
`and a set of PHY layers to provide fixed and mobile Broadband Wireless
`Access (BWA) in broad range of frequencies. The WiMAX forum has
`adopted IEEE 802.16 OFDM PHY layer for the equipment manufacturer
`due to its robust performance in multipath environment. The thesis
`investigates the simulation performance of IEEE 802.16 OFDM PHY
`layer. The Stanford University Interim (SUI) channel models are selected
`for the wireless channel in the simulation. The evaluation was done in
`simulation developed in MATLAB. Perfect channel estimation is
`assumed.
`
`Keywords: BWA, IEEE 802.16, WirelessMAN, FEC, OFDM
`
`ii
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 2 of 16
`
`
`
`Chapter 1
`
`Introduction
`
`This chapter provides a brief introduction on the motivation of this thesis work and its
`objective as well. At last the structure of the document is provided.
`
`1.1 Motivation
`Broadband Wireless Access (BWA) has emerged as a promising solution for last mile
`access technology to provide high speed internet access in the residential as well as small
`and medium sized enterprise sectors. At this moment, cable and digital subscriber line
`(DSL) technologies are providing broadband service in this sectors. But the practical
`difficulties in deployment have prevented them from reaching many potential broadband
`internet customers. Many areas throughout the world currently are not under broadband
`access facilities. Even many urban and suburban locations may not be served by DSL
`connectivity as it can only reach about three miles from the central office switch [3]. On
`the other side many older cable networks do not have return channel which will prevent
`to offer internet access and many commercial areas are often not covered by cable
`network. But with BWA this difficulties can be overcome. Because of its wireless nature,
`
`1
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 3 of 16
`
`
`
`it can be faster to deploy, easier to scale and more flexible, thereby giving it the potential
`to serve customers not served or not satisfied by their wired broadband alternatives.
`
`IEEE 802.16 standard for BWA and its associated industry consortium, Worldwide
`Interoperability for Microwave Access (WiMAX) forum promise to offer high data rate
`over large areas to a large number of users where broadband is unavailable. This is the
`first industry(cid:173)wide standard that can be used for fixed wireless access with substantially
`higher bandwidth than most cellular networks [2]. Wireless broadband systems have been
`in use for many years, but the development of this standard enables economy of scale that
`can bring down the cost of equipment, ensure interoperability, and reduce investment risk
`for operators.
`
`The first version of the IEEE 802.16 standard operates in the 10–66GHz frequency band
`and requires line(cid:173)of(cid:173)sight (LOS) towers. Later the standard extended its operation through
`different PHY specification to 2(cid:173)11 GHz frequency band enabling non line of sight
`(NLOS) connections, which require techniques that efficiently mitigate the impairment of
`fading and multipath [4]. Taking the advantage of OFDM technique the PHY is able to
`provide robust broadband service in hostile wireless channel.
`
`The OFDM(cid:173)based physical layer of the IEEE 802.16 standard has been standardized in
`close cooperation with the European Telecommunications Standards Institute (ETSI)
`High PERformance Metropolitan Area Network (HiperMAN) [5]. Thus, the HiperMAN
`standard and the OFDM(cid:173)based physical layer of IEEE 802.16 are nearly identical. Both
`OFDM(cid:173)based physical layers shall comply with each other and a global OFDM system
`should emerge [4]. The WiMAX forum certified products for BWA comply with the
`both standards.
`
`1.2 Objective
`The objective of this thesis is to implement and simulate the IEEE 802.16 OFDM
`physical layer using Matlab in order to have better understanding of the standard and the
`
`2
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 4 of 16
`
`
`
`system performance. This involves studying, through simulation, the various PHY
`modulation, coding schemes and interleaving in the form of bit(cid:173)error(cid:173)rate (BER) and
`block(cid:173)error(cid:173)rate (BLER) performance under reference channel models.
`
`1.2 Structure of the thesis
`The first chapter is an introduction of the thesis work. The rest of the chapters are
`organized as follows:
`Chapter 2 discusses the evolution and architecture of the IEEE 802.16 standard for BWA.
`Chapter 3 provides an overview of the IEEE 802.16 physical layer and OFDM technique.
`Chapter 4 deals with the PHY layer simulation model and SUI channel model employed
`by this thesis.
`Chapter 5 provides results obtained from the PHY layer simulation.
`Chapter 6 concludes with a summary of the research done and recommendation for future
`work.
`
`3
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 5 of 16
`
`
`
`Chapter 2
`
`IEEE 802.16: Evolution and
`Architecture
`
`This chapter discusses the evolution of the IEEE 802.16 standard for BWA to form the
`basis for further discussion. The protocol layers of the standard have been overviewed to
`get the idea of interaction between different protocol stack. The chapter ends up with a
`brief discussion of the IEEE 802.16 based network architecture, deployment topology,
`application scenarios and its affiliation with WiMAX forum.
`
`2.1 Evolution of IEEE family of standard for BWA
`In late 90’s many telecommunication equipment manufacturers were beginning to
`develop and offer products for BWA. But the Industry was suffering from an
`interoperable standard. With the need of a standard, The National Wireless Electronics
`Systems Testbed (N(cid:173)WEST) of the U.S National Institute of Standards and Technology
`(NIST) called a meeting to discuss the topic in August 1998 [6]. The meeting ended up
`with a decision to organize within IEEE 802. The effort was welcomed in IEEE 802,
`which led to formation of the 802.16 Working Group. Since then, the Working Group
`members have been working a lot to develop standards for fixed and mobile BWA. IEEE
`
`4
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 6 of 16
`
`
`
`Working Group 802.16 on Broadband Wireless Access (BWA) standard is responsible
`for development of 802.16 and the included WirelessMan™ air interface, along with
`associated standards and amendments.
`
`The IEEE 802.16 standard contains the specification of Physical (PHY) and Medium
`Access Control (MAC) layer for BWA. The first version of the standard IEEE802.16(cid:173)
`2001 [7] was approved on December 2001 and it has gone through many amendments to
`accommodate new features and functionalities. The current version of the standard IEEE
`802.16(cid:173)2004 [1], approved on September 2004, consolidates all the previous versions of
`the standards. This standard specifies the air interface for fixed BWA systems supporting
`multimedia services in licensee and licensed exempt spectrum [1]. The Working Group
`approved the amendment IEEE 802.16e(cid:173)2005 [8] to IEEE802.16(cid:173)2004 on February 2006.
`To understand the development of the standard to its current stage, the evolution of the
`standard is presented here.
`
`2.1.1 IEEE 802.16(cid:173)2001
`This first issue of the standard specifies a set of MAC and PHY layer standards intended
`to provide fixed broadband wireless access in a point(cid:173)to(cid:173)point (PTP) or point(cid:173)to
`multipoint (PMP) topology [7]. The PHY layer uses single carrier modulation in the 10 –
`66 GHz frequency range.
`
`Transmission times, durations and modulations are assigned by a Base Station (BS) and
`shared with all nodes in the network in the form of broadcast Uplink and Downlink maps.
`Subscribers need only to hear the base station that they are connected and do not need to
`listen any other node of the network. Subscriber Stations (SS) has the ability to negotiate
`for bandwidth allocation on a burst to(cid:173)burst basis, providing scheduling flexibility.
`
`The standard employs QPSK, 16(cid:173)QAM and 64(cid:173)QAM as modulation scheme. These can
`be changed from frame to frame and from SS to SS, depending on the robustness of the
`connection. The standard supports both Time Division Duplexing (TDD) and Frequency
`Division Duplexing (FDD) as duplexing technique.
`
`5
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 7 of 16
`
`
`
`An important feature of 802.16(cid:173)2001 is its ability to provide differential Quality of
`Service (QoS) in the MAC Layer. A Service Flow ID does QoS check. Service flows are
`characterized by their QoS parameters, which can then be used to specify parameters like
`maximum latency and tolerated jitter [10]. Service flows can be originated either from BS
`or SS. 802.16(cid:173)2001 works only in (Near) Line of Sight (LOS) conditions with outdoor
`Customer Premises Equipment (CPE).
`
`2.1.2 IEEE 8020.16a(cid:173)2003
`This version of the standard amends IEEE 802.16(cid:173)2001 by enhancing the medium access
`control layer to support multiple physical layer specifications and providing additional
`physical layer specifications. This was ratified by IEEE 802.16 working group in January
`2003[9]. This amendment added physical layer support for 2(cid:173)11 GHz. Both licensed and
`license(cid:173)exempt bands are included. Non Line of Sight (NLOS) operation becomes
`possible due to inclusion of below 11 GHz range, extending the geographical reach of the
`network. Due to NLOS operation multipath propagation becomes an issue. To deal with
`multipath propagation and interference mitigation features like advanced power
`management technique and adaptive antenna arrays were included in the specification
`[9]. The option of employing Orthogonal Frequency Division Multiplexing (OFDM) was
`included as an alternative to single carrier modulation.
`
`Security was improved in this version; many of privacy layer features became mandatory
`while in 802.16(cid:173)2001 they were optional. IEEE 802.16a also adds optional support for
`mesh topology in addition to PMP.
`
`2.1.3 IEEE 802.16c(cid:173)2002
`In December 2002, IEEE Standards Board approved amendment IEEE 802.16c [6]. In
`this amendment detailed system profiles for 10(cid:173)66 GHz were added and some errors and
`inconsistencies of the first version of the standard were corrected.
`
`6
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 8 of 16
`
`
`
`2.1.4 IEEE 802.16(cid:173)2004
`802.16(cid:173)2001, 802.16a(cid:173)2003 and 802.16c(cid:173)2002 were all together consolidated and a new
`standard was created which is known as 802.16(cid:173)2004. In the beginning, it was published
`as a revision of the standard under the name 802.16REVd, but the changes were so
`genuine that the standard was reissued under the name 802.16(cid:173)2004 at September 2004.
`In this version, the whole family of the standard is ratified and approved.
`
`Completed
`
`Spectrum
`Popagation/channel
`conditions
`Bit Rate
`
`Modulation
`
`Table 2.1: Comparison of IEEE standard for BWA
`
`IEEE 802.16(cid:173)
`2001
`December 2001
`
`IEEE 802.16a
`
`January 2003
`
`IEEE802.16(cid:173)
`2004
`June 2004
`
`IEEE 802.16e(cid:173)
`2005
`December 2005
`
`10(cid:173)66 GHz
`LOS
`
`2(cid:173)11 GHz
`NLOS
`
`2(cid:173)11 GHz
`NLOS
`
`2(cid:173)6 GHz
`NLOS
`
`Up to 134 Mbps
`(28 MHz
`channelization)
`QPSK, 16(cid:173)QAM
`(optional in UL),
`64(cid:173)QAM
`(optional)
`
`Up to 75 Mbps
`(20 MHz
`channelization)
`BPSK, QPSK,
`16(cid:173)QAM,
`64(cid:173)QAM,
` 256(cid:173)QAM
`(optional)
`
`Up to 75 Mbps
`(20 MHz
`channelization)
`256 subcarriers
`OFDM, BPSK,
`QPSK, 16(cid:173)QAM,
`64(cid:173)QAM, 256(cid:173)
`QAM
`
`Up to 15Mbps (5
`MHz
`channelization)
`Scalable
`OFDMA, QPSK,
`16(cid:173)QAM, 64(cid:173)
`QAM, 256(cid:173)QAM
`(optional)
`
`Mobility
`
`Fixed
`
`Fixed
`
`Fixed/Nomadic
`
`Portable/mobile
`
`2.1.5 IEEE 802.16e(cid:173)2005
`This amendment was included in the current applicable version of standard IEEE 802.16(cid:173)
`2004 in December 2005. This includes the PHY and MAC layer enhancement to enable
`combined fixed and mobile operation in licensed band.
`
`7
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 9 of 16
`
`
`
`2.2 IEEE 802.16 Protocol Layers
`The IEEE 802.16 standard is structured in the form of a protocol stack with well defined
`interfaces. As shown in Figure 2.1, the MAC layer is formed with three sublayers:
`
`¤ Service Specific Convergence Sublayer (CS)
`¤ MAC Common Part Sublayer (CPS) and
`¤ Privacy Sublayer.
`
`The MAC CS receives higher level data through CS Service Access Point (SAP) and
`provides transformation and mapping into MAC Service Data Unit (SDU). MAC SDUs
`are then received by MAC CPS through MAC SAP. The specification targeted two types
`of traffic transported through IEEE 802.16 networks: Asynchronous Transfer Mode
`(ATM) and Packets. Thus, Multiple CS specifications are available for interfacing with
`various protocols.
`
`The MAC CPS is the core part of the MAC layer, defining medium access method. The
`CPS provides functions related to duplexing and channelization, channel access, PDU
`framing, network entry and initialization. This provides the rules and mechanism for
`system access, bandwidth allocation and connection maintenance. QoS decisions for
`transmission scheduling are also performed within the MAC CPS.
`
`The Privacy layer lies between the MAC CPS and the PHY layer. Security is a major
`issue for public networks. This sub layer provides the mechanism for encryption and
`decryption of data transferring to and from PHY layer and is also used for authentication
` and secure key exchange. Data, PHY control, statistics are transferred between the MAC
`CPS and the PHY through the PHY SAP.
`
`8
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 10 of 16
`
`
`
`Management Entity
`
`Service Specific CS
`
`Management Entity
`
`MAC CPS
`
`Security Sublayer
`
`Management Entity
`PHY
`
`Scope of standard
`
`CS SAP
`
`Service(cid:173)Specific
`Convergence Sublayer (CS)
`
`MAC SAP
`
`MAC Common Part
`Sublayer (MAC CPS)
`
`Security Sublayer
`
`PHY SAP
`
`Physical Layer (PHY)
`
`MAC
`
`PHY
`
`Data /Control Plane
`
`Management Plane
`
`Figure 2.1: IEEE 802.16 Protocol Stack
`
`The PHY layer includes multiple specifications, which make the standard adaptable to
`different frequency ranges. The flexibility of the PHY enables the system designers to
`tailor their system according to the requirements. The PHY specifies some mandatory
`features to be implemented with the system including some optional features.
`
`2.3 Network Architecture and Deployment Topology:
`An IEEE 802.16 network is consists of fixed infrastructural sites. In fact, the IEEE
`802.16 network is resembled to cellular phone network. Each cell consists of a Base
`
`9
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 11 of 16
`
`
`
`Station (BS) and one or more subscribe station (SS), depending on the implementation of
`the topology. Therefore, the BS provides Point to Point (PTP) service or Point to Multi(cid:173)
`point (PMP) service in order to serve multiple SSs. BSs provide connectivity to core
`networks. The SS can be a roof mounted or wall mounted customer premises equipment
`(CPE) or a stand alone hand held device like Mobile phone, personal digital assistant
`(PDA) or peripheral component interconnect (PCI) card for PC or Laptop. In case of a
`outside CPE, the users inside the building are connected to a conventional network like
`Ethernet Local Area Network (IEEE 802.3 for LAN) or Wireless LAN (IEEE 802.11b/g
`for WAN) which have access to the CPE. A group of cells can be grouped together to
`form a network, where BSs are connected through a core network, as shown in Figure
`2.2. The IEEE 802.16 network also support mesh topology, where SSs are able to
`communicate among them selves without the need of a BS [1].
`
`SSs
`
`BS
`
`SSs
`
`BS
`
`SSs
`
`BS
`
`Core Network
`
`Figure 2.2: A typical IEEE 802.16 Network
`BSs typically employ one or more wide beam antennas that may be partitioned into
`several smaller sectors, where all sectors sum to a complete 360 degree coverage. CPEs
`typically employ highly directional antennas that are pointed towards the BS. Depending
`on the need, IEEE 802.16 network can be deployed in different forms.
`
`10
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 12 of 16
`
`
`
`2.4 Application of IEEE 802.16 based network:
`IEEE 802.16 supports ATM, IPv4, IPv6, Ethernet and Virtual Local Area Network
`(VLAN) services [1]. SO, it can provide a rich choice of service possibilities to voice and
`data network service providers. It can be used for a wide selection of wireless broadband
`connection and solutions.
`
`¤ Cellular Backhaul: IEEE 802.16 wireless technology can be an excellent choice
`for back haul for commercial enterprises such as hotspots as well as point(cid:173)to(cid:173)point
`back haul applications due to its robust bandwidth and long range.
`
`¤ Residential Broadband: Practical limitations like long distance and lack off return
`channel prohibit many potential broadband customers reaching DSL and cable
`technologies [3]. IEEE 802.16 can fill the gaps in cable and DSL coverage.
`
`¤ Underserved areas: In many rural areas, especially in developing countries, there is
`no existence of wired infrastructure. IEEE 802.16 can be a better solution to
`provide communication services to those areas using fixed CPE and high gained
`antenna.
`
`¤ Always Best Connected: As IEEE 802.16e supports mobility [8], so the mobile
`user in the business areas can access high speed services through their IEEE
`802.16/WiMAX enabled handheld devices like PDA, Pocket PC and smart phone.
`
`11
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 13 of 16
`
`
`
`Figure 2.3: Application scenarios [3]
`
`2.5 WiMAX forum and adaptation of IEEE 802.16
`
`The Worldwide Interoperability for Microwave Access (WiMAX) forum is an alliance of
`telecommunication equipments and components manufacturers and service providers,
`formed to promote and certify the compatibility and interoperability of BWA products
`employing the IEEE 802.16 and ETSI HiperMAN [17] wireless specifications. WiMAX
`Forum Certified™ equipment is proven interoperable with other vendors’ equipment that
`is also WiMAX Forum Certified™ [33]. So far WiMAX forum has setup certification
`laboratories in Spain, Korea and China. Additionally, the WiMAX forum creates what it
`calls system profiles, which are specific implementations, selections of options within the
`standard, to suit particular ensembles of service offerings and subscriber populations
`[19].
`
`WiMAX forum has adopted two version of the IEEE 802.16 standard to provide different
`types of access:
`
`12
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 14 of 16
`
`
`
`¤ Fixed/Nomadic access: The WiMAX forum has adopted IEEE802.16(cid:173)2004 and
`ETSI HyperMAN standard for fixed and nomadic access [17]. This uses
`Orthogonal Frequency Division Multiplexing and able to provide supports in Line
`of Sight (LOS) and Non Line of Sight (NLOS) propagation environment. Both
`outdoor and indoor CPEs are available for fixed access. The main focus of the
`WiMAX forum profiles are on 3.5 GHz and 5.8 GHz frequency band.
`
`¤ Portable/Mobile Access: The forum has adopted the IEEE 802.16e version of the
`standard, which has been optimized for mobile radio channels. This uses Scalable
`OFDM Access and provides support for handoffs and roaming [17]. IEEE 802.16e
`based network is also capable to provide fixed access. The WiMAX Mobile
`WiMAX profiles will cover 5, 7, 8.75, and 10 MHz channel bandwidths for
`licensed worldwide spectrum allocations in the 2.3 GHz, 2.5 GHz, 3.3 GHz and
`3.5 GHz frequency bands [18]. The first certified product is expected to be
`available by the end of 2007.
`
`13
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 15 of 16
`
`
`
`Chapter 3:
`
`IEEE 802.16 Physical Layer
`
`This chapter discusses about the different variants of the IEEE 802.16 PHY layer with
`their capabilities and conditions of operation. The OFDM based physical layer has been
`overviewed with its various mechanisms. Finally the chapter concludes with a discussion
`on OFDM technology and its design considerations.
`
` 3.1 IEEE 802.16 PHY Layer:
`The IEEE 802.16 standard supports multiple physical specifications due to its modular
`nature. The first version of the standard only supported single carrier modulation. Since
`that time, OFDM and scalable OFDMA have been included to operate in NLOS
`environment and to provide mobility. The standard has also been extended for use in
`below 11 GHz frequency bands along with initially supported 10(cid:173)66 GHz bands.
`
`3.1.1 Supported Band of Frequency
` The IEEE 802.16 supported licensed and unlicensed bands of interest are as follows:
`
`14
`
`Intel Corporation Ex. 1023
`Intel Corp v. UNM Rainforest Innovations - IPR2020-01576
`Page 16 of 16
`
`