A Survey Paper on WiMAX Technology

IJIRST –International Journal for Innovative Research in Science & Technology| Volume 2 | Issue 11 | April 2016 ISSN (online): 2349-6010 A Survey Paper on WiMAX Technology Atul S. More UG Student Department of Electronics and Telecommunication Engineering SRTTC Abstract ABSTRACTWireless Networking has become an important area of research in industry and academics in recent years. The main objectives of this paper are to gain knowledge about the WiMAX technology, its security and application. WiMAX (Worldwide Interoperability for Microwave Access) technology is based upon the IEEE 802.16 standard (IEEE Wireless MAN Air Interface) which enables wireless broadband services anytime, anywhere. The WiMAX specification provides symmetrical bandwidth over large area and range with stronger encryption and typically less interference. WiMAX based system can be used to transmission of signal over maximum 50 km. WiMAX outdistances WiFi by miles. WiMAX can deliver high data rate to multiple users. The WiMAX Forum describes WiMAX as” a standards-based technology enabling the delivery of last-mile wireless broadband access as an alternative to cable and DSL”. The main goal/purpose of this technology is to deliver wireless communications with quality of service in a secured environment. This standard was developed to deliver line-of-sight (LoS) and non-line-of-sight (NLoS) wireless services between subscriber and base station and to address “last mile” problem. Keywords: WiMAX, WiFi, LTE, OFDM, OFDMA, Security etc _______________________________________________________________________________________________________ I. INTRODUCTION The name “WiMAX” is given by the organization named as “WiMAX Forum” which is non-profit organization created to promote WiMAX. WiMAX is a broadband wireless access method which provides fixed and mobile Internet access. The Standard names of WiMAX are 802.16, 802.16a, 802.16d, 802.16e and 802.16m. WiMAX can provide up to 40Mbit/s using the IEEE802.16m and maximum speed is up to 1Gbit/s. In WiFi, wireless local area network is limited to 54Mbit/s to 600Mbit/s. Maximum range for WiMAX is 50km (31miles) and of WiFi is 330ft (100m). Fig. 1: Logo of WiMAX Forum Org Fig. 2: Logo of IEEE 802.16 WirelessMAN Org WiMAX is expected to provide fixed and nomadic wireless connectivity without necessarily having a line-of-sight with base station. The IEEE 802.16 sets standards for an IP packet-based system and can be deployed in either FDD or TDD configuration. [1]It also has the ability to maintain dedicated links and VOIP services at a reliable and high quality speed. WiMAX provides high All rights reserved by www.ijirst.org 447 A Survey Paper on WiMAX Technology (IJIRST/ Volume 2 / Issue 11/ 078) data rates, last mile wireless access, large frequency range, point to multipoint communication and quality of services for various applications. [2] Modulation WirelessMAN OFDMA is among the three specifications defined in IEEE 802.16 family for applications below 11GHz of frequency. In OFDMA mode, the active subcarriers are divided into subsets of subcarriers, where each subset is termed a subchannel. In the downlink and uplink, a sub-channel may be intended for diferent receiver and may be assigned for different transmitter respectively.OFDMA(Orthogonal Frequency-Division Multiple Access) was chosen for use in WiMAX because it has high specral efficiency , resilient to multipath propagation problems and it has added benefit of reduced receiver complexity.OFDMA enables MIMO capability in the downlink and supports parallel data streams.[3] Depending upon the data requirement and condition modulation and coding is set individually for each subscriber. OFMDA provides subchannelization which results in complex signals than OFDM but offers bettter performance and scalability. OFDMA optimizes the use of network resources by allowing transmitter power adapting seperately. Power of the user device is saved because of subchannelization in uplink by concentrating power to the selected subchannels allocated to it. Subchannelization uses orthogonal frequency-division multiple access with a 2048-point transform and is designed for NLoS operations. An OFDMA symbol consists of a number of carriers equal to size of the Fourier Transform and they are constructed from Data, Pilot and Null Carriers. The IEEE 802.16e-2005 air interface, suppots both FDD and TDD. In case of TDD, the uplink and downlink sub-frames are transmitted on the same carrier frequency at different times while in case of FDD, the uplink and downlink sub-frames are transmitted simultaneously on different carrier frequencies. [5] MAC Layer MAC (Medium Access Control) layer lies above the PHY layer of the open system interconnect protocol stack layers. The Primary objective of this layer is to provide interface between transport layer and physical layer. The MAC layer takes packets from transport or upper layers and organizes them into MAC Protocol for transmission over air. The WiMAX, IEEE 802.16 MAC protocol was designed for point-to-multipoint broadband wireless access application and is based on collision sense multiple access with collision avoidance. MAC also supports mesh architecture. The IEEE 802.162004 and IEEE 802.16e-2005 MAC design includes convergence sub layer that can interface with the higher-layer protocols, such as ATM TDM voice, Ethernet , IP and any future protocols. The MAC layer provides several features suitable for broad range of applications, such as, PKM; broadcast and multicast support; Manageability primitives; high speed handover and mobility management primitives; three power management levels, normal operation, sleep and idle, Header suppression, packing and fragmentation for efficient use of spectrum. It supports high bandwidth and hundreds of users per channel and is a point to multipoint protocol (P2MP).Spectrum is used efficiently by supporting high traffic. The MAC Layer provides packet fragmentation, ARQ and QOS. The MAC Privacy sub-layer introduces security features in WiMAX. Like Authentication, Encryption and Key exchange functionality are provided. The four basic actions of communication are done in this layer which are; creation of connection, modification of connection, deletion of connection and transport of data over the connection. II. SECURITY WiMAX uses radio channels which are open channels and hence pose very serious security problems for traffic confidentiality and integrity because of use of air medium which exposes the PHY and MAC layers. WiMAX has a robust level of authentication and security. Security is not done at the time of system access only but also during session and data transfer.MAC sub-layer provides the security based on privacy key management protocol. All the data that is transmitted in WiMAX network is virtually encrypted and it uses 168-bit Digital Encryption Standard (3DES). Authorization Authorization is the process in which SS requests for an Authorization Key and a SAID from Base Station by sending an Authorization Request Message. Which uses X.509 digital certificates, encryption algorithm and cryptographic ID. [1][4] Base Station then interacts with an AAA (Authentication, Authorization and Accounting) server to validate request from the Subscriber Station, and sends back an Authorization Reply which includes the Authorization encrypted with the Subscriber Stations public key, a lifetime key and an SAID. Security Association (SA) Security Association is a set of security information (Parameters) that a base station and one or more of its client Subscriber Station share. Each Security Association has its own identifier and contains cryptographic suite identifier. [1]The role of SA is to maintain the security state relevant to connection; it operates at MAC Layer. All rights reserved by www.ijirst.org 448 A Survey Paper on WiMAX Technology (IJIRST/ Volume 2 / Issue 11/ 078) Public Key Infrastructure WiMAX uses protocols like Privacy and Key Management Protocol (PKM) for secure key transfer, management and exchange between mobile stations. This Protocol also authenticates Subscriber Station to a Base Station. [4] The PKM Protocol also uses X.509 digital certificates, Rivest-Shamir-Adleman (RSA) public key algorithm. The PKM authorization protocol is used to distribute authorization key to Subscriber Station (Authorized).This involves some message exchanges (exact 3). Message 1: PKM-REQ: Authorization Info. SS->BS Message 2: PKM-REQ: Authorization Request SS->BS Message 3: PKM-RSP: Authorization Reply BS->SS Certificate Profile The standard uses X.509v3 Certificates to identify communicating parties in network. There are two types of Certificates in this standard: manufacture certificates and subscriber station certificates. The manufacture certificate identifies the manufacture of WiMAX 802.16 devices. This certificate include following formats:  X.509v3  Issuer Name  Serial Number  Issuer’s Signature algorithm  Validity Period  Holder’s identity  Holder’s Public Key  Subject signature algorithm Encryption The EAS encryption is used for encrypting over the air traffic in network. WiMAX uses 3DES and AES to encrypt the data transferred over network. The slow performance and limit on length of keys is slowly making 3DES obsolete because it uses 3 keys which in returns affect the performance. The main tool for encryption now used by WiMAX is Advanced Encryption Standard (AES). It provides support for 128-bit, 192-bit, 256-bit encryption key. AES was build from Counter Mode with Cipher Block Chaining Message, CCM, and Authentication code. With this, the sender generates a unique value per packet and sends this value to receiver. This prevents manin-the-middle attacks. AES is faster than 3DES, easy to implement and uses less memory. Also an additional measure introduced to use Traffic Encryption State Machine which uses a periodic key refresh mechanism to provide for continued transition of keys. III. TYPES OF WIMAX WiMAX can be differentiated/grouped into two basic standards types, fixed and portable/mobile. The WiMAX standards are continuously evolving to keep up with other standards in various advances that are being made with unique protocols. Fixed WiMAX WiMAX can be used for point to point communication. Fixed wireless access protocols are designed in IEEE 802.16 Standard 2004 Release. The Standard 802.16d is referred as Fixed WiMAX. Mounted antennas used at subscriber’s site for data transmission. So may be referred as “Fixed Wireless” and those antennas are mounted on roof/mast, similar to a satellite television dish. The IEEE 802.16 2004 Release addresses indoor installations for safety purpose. It connects businesses and homes to high speed Internet. Orthogonal Frequency Division Multiplexing (OFDM) modulation is used in Fixed WiMAX which supports subchannelization in the Uplink. OFDM breaks the wireless carrier into 256 subcarriers. [2] Portable/Mobile WiMAX The IEEE 802.16 Standard 2004 Release also provides goals for portability. The Standards 802.16e and 802.16m supports the mobility. WiMAX has the ability to support both 3G and 4G technology. The WiMAX standard 802.16e comes under the 3G classification (IMT-2000) while 802.16m is classified as a 4G technology (IMT-2000Advanced).[2] Orthogonal Frequency Division Multiple Access (OFDMA) modulation is used in mobile WiMAX. OFDMA is similar to that of OFDM just more improved version. In this, multiple subcarriers grouped into subchannels. OFDMA improves multipath performance. [3] All rights reserved by www.ijirst.org 449 A Survey Paper on WiMAX Technology (IJIRST/ Volume 2 / Issue 11/ 078) IV. TECHNICAL COMPARISONS Table - 1 Technical Comparisons of WiFi, LTE and WiMAX Common Name WiFi LTE WiMAX Family 802.11(11n) 3GPP 802.16(16m) Primary Use Mobile Internet General 4G WirelessMAN Radio Technology OFDM/MIMO OFDMA/MIMO/SC-FDMA MIMO-SOFDMA Range In meters In km In km Bandwidth(Expected) 2Mbps 100-1000Mbps 75-1000Mbps V. FEATURES AND APPLICATIONS Multicast and Broadcast Services (MBS) This feature of WiMAX enables the same data content to be transferred to multiple users at the same time as a broadcast message.MBS has many attributes as DVB-H, LTE, and MediaFLO. This minimizes the resource consumption of the network in case of delivering the same streaming video or audio. [1] Residential and Small Office/Home Office (SOHO) Internet Access Internet access for residential and SOHO is provided by DSL and Cable. These two technologies covers large market and are well established. Also fulfils demands of the customers. WiMAX provides an alternative to the way of Internet access by not using DSL and Cable. Wireless nature of WiMAX gives it advantage in providing connectivity in remote areas and is more reliable. Power Management Power Management is essential for wireless mobility systems to improve performance and battery life of the subscriber unit. The subscriber unit is either turned ON or OFF because of power management. There are three modes, active, sleep and idle when the device is turned ON. [1] Provide broadband and QOS guarantee data transmissions using wireless links. Uses licensed spectrum and point-to-multipoint architecture. Providing Nomadic connectivity and WiFi hotspots service. VI. CONCLUSION A large broadband wireless access network based on the WiMAX Standard provides a common infrastructure with all the attributes and features required for high performance, high speed and cost effective. This Paper provided quick overview of concept, technology, standard, security and applications for IEEE 802.16 WiMAX. REFERENCES [1] [2] [3] [4] [5] Clint Smith and Daniel Collins, “Wireless Networks, Design and Integration for LTE, EVDO, HSPA, and WiMAX,”McGraw Hill Education, 2014 Bhuteswar Jena, “Fixed and Mobile WiMAX Networks based on LTE,” International Journal of Computer Science and Information Technology, Vol. 5(5), 2014 Ahmed M Husein Shabani, Prof. M.T.Beg and Ammar Abdul-Hamed Khader, “Survey of Down Link Data Allocation Algorithms in IEEE 802.16 WiMAX,” International Journal of Distributed and Parallel Systems (IJDPS) Vol.3, No.4, July 2012 Amit Singla and Dr. Sumeet Gill, “Survey on Security Issues in Various Wireless Networks,”International Journal of Advanced Research in Computer Science and Software Engineering, Vol. 4,Issue 3, March 2014 R. Prasad and F. J. Velez, “WiMAX Networks Techno-Economic Vision and Challenges,”2010 All rights reserved by www.ijirst.org 450