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4G Mobile Communications ( WiMAX and LTE)

4G Mobile Communications ( WiMAX and LTE). Personal. WAN. GSM, CDMA, UMTS… 3GPP. 802.15.3 Bluetooth 60 GHz UWB. MAN. Wide. LAN. TVWS. PAN. 802.22. RAN. Regional. 802.11 Wi-Fi. Metro. Local. 802.16 WiMAX. Cognitive Radio The IEEE 802.22 standard.

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4G Mobile Communications ( WiMAX and LTE)

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  1. 4G Mobile Communications (WiMAX and LTE) www.assignmentpoint.com

  2. Personal WAN GSM, CDMA, UMTS… 3GPP 802.15.3 Bluetooth 60 GHz UWB MAN Wide LAN TVWS PAN 802.22 RAN Regional 802.11 Wi-Fi Metro Local 802.16 WiMAX www.assignmentpoint.com

  3. Cognitive Radio The IEEE 802.22 standard • IEEE 802.22, is a standard for wireless regional area network (WRAN) using white spaces (vacant TV channels) in the television (TV) frequency spectrum (in the VHF and UHF bands).  • Operates in the range of frequencies between 54 MHz and 862 MHz. • Operates in lower population density areas. • The development of the IEEE 802.22 WRAN standard is aimed at using cognitive radio (CR) techniques to allow sharing of geographically unused spectrum allocated to the television broadcast service. www.assignmentpoint.com

  4. Overview of IEEE 802.22 Standard www.assignmentpoint.com

  5. History • In March 2008, the InternationalTelecommunications Union-Radio communications (ITU-R) specified a set of requirements for 4G standards, named the International Mobile Telecommunications Advanced (IMT-Advanced) specification, setting peak speed requirements for 4G service at 300 Mbit/s for high mobility communication (such as from trains and cars) and 1Gbit/s for low mobility communication (such as pedestrians and stationary users). • Since the first-release versions of Mobile WiMAX (first used in South Korea in 2007) and LTE (in Oslo, Norway and Stockholm, Sweden since 2009 )support much less than 1 Gbit/s peak bit rate, they are not fully IMT-Advanced compliant, but are often branded 4G by service providers. • On December 6, 2010, ITU-R recognized that these two technologies, as well as other beyond-3G technologies that do not fulfill the IMT-Advanced requirements, could nevertheless be considered "4G", provided they represent forerunners to IMT-Advanced compliant versions . www.assignmentpoint.com

  6. During the spring 2011 above two system provide their advanced version as: Mobile WiMAX Release 2 (also known as WirelessMAN-Advanced or IEEE 802.16m') and LTE Advanced (LTE-A, Based on UMTS 3G technology) and promising speeds in the order of 1 Gbit/s in 2013. www.assignmentpoint.com

  7. Comparison of 3G and 4G www.assignmentpoint.com

  8. Some Key Challenges Coverage Transmit power limitations and higher frequencies limit the achievable cell size Capacity Current air interfaces have limited peak data rate, capacity, and packet data capability Spectrum Lower carrier frequencies (< 5 GHz) are best for wide-area coverage and mobility www.assignmentpoint.com

  9. WiMAX • Wi-MAX: The Worldwide Interoperability for Microwave Access, is a technology aimed at providing wireless data over long distances It is based on the IEEE 802.16 standard. www.assignmentpoint.com Fig.1

  10. WiMAX • In 1998 IEEE802.16 protocol was developed to provide high speed service of WMAN (Wireless Metropolitan Area Network). Next two new version of above protocol were found as: IEEE 802.16d (in 2004) was developed to support high speed wireless data service of fixed user and its later version IEEE 802.16e (in 2005) supports both fixed and mobile users. • With the advent of OFDMA based IEEE 802.16e, research is now going on to implement VoIP service with adaptive modulation and channel coding (MCS) scheme. To enhance the throughput of the wireless system the modulation and coding scheme of the transmitter is changed according to the fading condition of the channel. • Therefore the service becomes a variable bit rate service where the bit rate depends on the fading condition of the wireless channel. www.assignmentpoint.com

  11. WiMAX • Three common types of BW allocation algorithms are:Dedicated Resource Allocation (Unsolicited Grand Service known as UGS Algorithm) where fixed amount of BW is allocated to each user hence possibility of waste of BW when a user needs to data send data at low rate; Polling-Based Resource Allocation (Real-Time Polling Service called rtPS Algorithm) where BS allocates the BW dynamically therefore incurs some protocol overhead and delay; Hybrid Resource Allocation Algorithm is the combination of above two. • WiMAX also can be used as a complementary system to Wi-Fi. Both of the two major 3G systems: CDMA2000 and UMTS, compete with WiMAX. www.assignmentpoint.com

  12. WiBro, Korean version of WiMAX has been deployed in Korea. • WiFi and WiMAX are the B3G (Beyond 3G) systems. WiMAX may be an interim system of a 4G system. www.assignmentpoint.com

  13. Some important features of WiMAX are given below: OFDM in physical layer: The access technique used in physical layer of WiMAX is OFDM; where the high speed serial data is converted to low rate parallel streams and each stream is modulated by separate carrier each one is known as subcarrier. Subcarriers are mutually orthogonal and deals with low data rate hence can protect multipath fading. Very high peak data rates: The data rate of WMAX is 70Mbps under the channel of bandwidth of 20 MHz. The rate can be further increased using space division multiplexing i.e. incorporation of multiple antennas. www.assignmentpoint.com

  14. Adaptive Modulation and Coding: The IEEE 802.16e standard changes modulation and channel coding scheme based on received SNR. For example a SS close to the BS can use a high modulation scheme (more bits per symbol) i.e. the system can get more capacity but when the SS is at the cell boarder the system permits lower modulation scheme (increased signal space on orthogonal basis function coordinate system) to avoid huge symbol error rate. Therefore the system can overcome the time selective fading (the channel condition is better at some instant than other). Error Correction Techniques: WiMAX incorporates two types of strong error correction techniques: FEC (Forward Error Correction) for multimedia traffic and ARQ (Automatic Repeat Request) for data traffic to improve throughput.  www.assignmentpoint.com

  15. Support for TDD and FDD: Like mobile cellular communication it supports both FDD (Frequency division duplexing) and TDD (Time division duplexing), as well as a half-duplex FDD. Above features provide the flexibility of using same or different carriers for up and down link. www.assignmentpoint.com

  16. IEEE 802.16 general architecture www.assignmentpoint.com

  17. WiMAX applications and missions www.assignmentpoint.com BWA (Broadband Wireless Access)

  18. OFDMA Based WiMAX Network We consider a single cell in a WiMAX network with a base station and multiple subscriber stations (Fig.2). Each subscriber station serves multiple connections. Admission control is used at each subscriber station to limit the number of ongoing connections through that subscriber station. At each subscriber station, traffic from all users for uplink connections are aggregated into a single queue. www.assignmentpoint.com

  19. Fig.2 System model The size of this queue is finite (i.e., X packets) in which some packets will be dropped if the queue is full upon their arrivals. The OFDMA transmitter at the subscriber station receives packets and transmits them to the base station. The base station may allocate different number of subchannels to different subscriber stations. For example, a subscriber station with higher priority could be allocated more number of subchannels. www.assignmentpoint.com

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  21. 1. What is 4G? Wireless Technology Evolution to 3.9G CDMA IEEE Cellular IEEE LAN GSM/UMTS CDMA (IS-95A) GSM TDMA IS-136 IEEE 802.16 IEEE 802.11 2G CDMA (IS-95B) GPRS 802.11g 2.5G cdma 2000 E-GPRS EDGE WCDMA FDD/TDD TD-SCDMA LCR-TDD 802.11a 3G 1xEV-DO Rev 0/A/B HSDPA FDD/TDD HSUPA FDD/TDD Fixed WiMAX 802.16d WiBRO 802.11g 3.5G UMB 802.20 HSPA+ Mobile WiMAX 802.16e 802.11n LTE E-UTRA 3.9G UMB (Ultra Mobile Broadband) was the brand name for a project within 3GPP2 to improve the CDMA 200 mobile phone standard for next generation applications and requirements. No carrier had announced plans to adopt UMB, and most CDMA carriers in Australia, USA, Canada, China, Japan and South Korea have already announced plans to adopt either WiMAX or LTE as their 4G technology. www.assignmentpoint.com

  22. In a hierarchical telecommunications network the backhaul portion of the network comprises the intermediate links between the core network or backbone, of the network and the small sub-networks at the "edge" of the entire hierarchical network. www.assignmentpoint.com

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  26. The 802.16 Protocol Stack The IEEE 802.16 data link layer layer is composed of three sub-layers Service Specific Convergence Sub-layer (CS), MAC Common Part Sub-layer (CPS) and the Security Sub-layer. Each sub-layer has a specific function to perform. www.assignmentpoint.com The 802.16 protocol stack

  27. Upper layers Service specific convergence layer MAC sub-layer Security sub-layer Transmission convergence sub-layer QPSK 16-QAM 64-QAM Layers of WiMAX Data link layer Physical layer Fig.5 The 802.16 protocol stack www.assignmentpoint.com

  28. 802.16 PHY The IEEE 802.16e supports both time division duplexing (TDD) and frequency division duplexing (FDD) modes. However, the initial release of Mobile WiMAX profiles only considers the TDD mode of operation for the following reasons: Time Division Duplexing Time division duplexing (TDD) refers to the interleaving of transmission and reception of data on the same frequency. A common frequency is shared between the upstream and downstream, the direction in transmission being switched in time. Frequency Division Duplexing Frequency division duplexing (FDD) refers to the simultaneous transmission and reception of data over separate frequencies, allowing for bidirectional full-duplex communications. www.assignmentpoint.com

  29. A single frequency channel in (downlink) DL and (uplink)UL can provide more flexibility for spectrum allocation. It enables dynamic allocation of downlink (DL) and uplink (UL) radio resources to effectively support asymmetric DL/UL traffic that is common in Internet applications. It supports link adaptation, multi-input-multi-output (MIMO) techniques, and closed loop advanced antenna technique such as beam-forming. www.assignmentpoint.com

  30. Adaptive Modulation and Coding • An SS (subscriber Station) close to the BS could use a high modulation scheme, thereby giving the system more capacity. In contrast, a weak signal from a more remote subscriber might only permit the use of a lower modulation scheme to maintain the connection quality and link stability. • This feature enables the system to overcome time-selective fading. • The coding rate also change according received SNR of fading channel. • Modulation • QPSK, 16-QAM, 64-QAM www.assignmentpoint.com

  31. Modulation Coding Schemes (MCSs) PDU → Packet Data Unit SDU → Service Data Unit lm → the number of PDU allocated for a TDMA slot www.assignmentpoint.com

  32. Uplink scheduling is feasible if the allocated uplink resources are less than the total of available resources (number of PDU/slot) Nslot,u. Hence, we have where the parameter lm is the size of the VoIP PDU, which is modulated with the mth MCS level after encoding and xm is the number of PDU at mth MCS level. www.assignmentpoint.com

  33. For example, we consider Nslot,u = 50 and M = 4. Then,the MCS-level distributions of packets are denoted as, X =(x1, x2, x3, x4). If the MCS-level distributions of six packets in the uplink queue are (0, 0, 0, 6) or (0, 0, 1, 5) and the MCS level of the seventh packet in the queue is not four, the BS schedules six packets according to the uplink feasibility condition. X = (0, 0, 0, 6) = 0 + 0 + 0 + 6*6 = 36 <50 X = (0, 0, 1, 5) = 0 + 0 + 1*12 + 5*6 = 42 < 50 www.assignmentpoint.com

  34. However, if the MCS level of the seventh packet is four, the BS can schedule more packets than six because the MCS-level distribution of seven packets becomes (0, 0, 0, 7) or (0, 0, 1, 6), which satisfies feasibility condition. X = (0, 0, 0, 7) = 0 + 0 + 0 + 6*7= 42 <50 X = (0, 0, 1, 6) = 0 + 0 + 1*12 + 6*6= 48 <50 www.assignmentpoint.com

  35. Upper layers Service specific convergence layer MAC sub-layer Security sub-layer Transmission convergence sub-layer QPSK 16-QAM 64-QAM Data link layer From the reference model as illustrated in Figure 5, there are three sub-layers in the data link layer composed of i) a security sublayer, ii) a MAC common part sublayer, and iii) a convergence sublayer. It provides only connection oriented service Fig.5 The 802.16 protocol stack www.assignmentpoint.com

  36. Service Specific Convergence Sub-layer (CS): • The CS, which is the interface between the MAC layer and layer 3 of the network, receives data packets from the higher layer. These higher layer packets are known as service data unit (SDU). • The CS is responsible for performing all operations that are dependent on the nature of higher-layer protocol, such a header compression and address mapping. The CS can be viewed as an adaptation layer that masks the higher-layer protocol. • Packet header suppression (PHS): At the transmitter it involves removing the repetitive part of the header of each SDU. For example, if the SDUs delivered to the CS are IP packets, the source and destination addresses contained in the header of each IP packet do not change from one packet to the next and thus can be removed before being transmitted over the air. Similarly at the receiver: the repetitive part of the header can be reinserted into the SDU before being delivered to the higher layer. www.assignmentpoint.com

  37. CS is also responsible for the mapping the higher layer address, such as IP address, of the SDUs into the identity of the PHY and MAC connections to be used for its transmission. The WiMAX MAC layer is connection oriented and identifies a logical connation between the BS and the MS by a unidirectional connection identifier (CID). The CID for UP and DL connections are different. www.assignmentpoint.com

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  39. MAC Common Part Sublayer • The MAC layer takes packets from the upper layer (CS) and these packets are called MAC service data units (MSDUs) and organize them into MAC protocol data units (MPDUs) for transmission over the air. • The WiMAX MAC uses a variable length MPDU and offer a lot of flexibility to allow for their efficient transmission. For example multiple MPDUs of same or different lengths may be arranged into a single burst when they are destined to the same receiver. www.assignmentpoint.com

  40. Similarly , multiple MSDUs from the same higher-layer service may be concatenated into a single MPDU to save MAC header overhead. • Large MSDUs may be fragmented into smaller MPDUs and send across multiple frames. When an SDU is fragmented, the position of each fragment within the SDU is tagged by a sequence number. The sequence number enables the MAC layer at the receiver to assemble the SDU from its fragments in the correct order. • WiMAX has two types of PDUs, each with a very different header structure. • The generic MAC PDU is used for carrying data and MAC-layer signaling messages. • The bandwidth request PDU is used by the MS to indicate to the BS that more BW is required in UL, due to pending data transmission. A bandwidth request PDU consists only of a bandwidth-request header, with no payload or CRC. www.assignmentpoint.com

  41. Each MAC frame is prefixed is prefixed with GMH (generic MAC header). • Field (in SH) to indicate whether the payload is encrypted or not. If the payload is encrypted then the encryption key is also given. • Header CRC field is a checksum over the header only using the generator polynomial x8+x2+x+1. The length of this field is 8bits. GMH Other SH Packed fixed size MSDU Packed fixed size MSDU CRC ……. Fig.6 MAC PDU frame carrying several-fixed length MSDUs packed together GMH → Generic MAC Header (used for carrying data and MAC-layer signaling messages) SH → Sub-header www.assignmentpoint.com

  42. LEN H E rs C EKS rs msb Type (6 bits) T C v I (2) v (3) CID msb (8) LEN lsb (8) HCS (8) CID lsb (8) Generic MAC Header Fields www.assignmentpoint.com

  43. BW Req. H E Type (3 bits) T C msb (11) CID msb (8) BWS Req. lsb (8) HCS (8) CID lsb (8) Bandwidth Request MAC Header Fields www.assignmentpoint.com

  44. GMH Other SH FSH MSDU Fragment CRC GMH Other SH PSH Variable size MSDU or Fragment PSH Variable size MSDU or Fragment CRC … Fig.7 MAC PDU frame carrying a single fragmented MSDU Fig.8 MAC PDU frame carrying several variable length MSDUs packed together FSH → Fragmentation Sub-header PSH → Packing Sub-header The type of payload is identified by the sub-header immediately precedes it. For example FSH or PSH of above figure. www.assignmentpoint.com

  45. Generic MAC Header Format BW Req. Header Format (Header Type (HT) = 0) (Header Type (HT) =1) LEN BW Req. H E rs C EKS rs H E msb Type (6 bits) Type (6 bits) T C v I (2) v T C msb (8) (3) CID msb (8) LEN lsb (8) CID msb (8) BWS Req. lsb (8) HCS (8) CID lsb (8) HCS (8) CID lsb (8) msb lsb Generic MAC CRC payload (optional) Header MAC PDU (optional) (6 bytes) www.assignmentpoint.com

  46. Privacy (or Security) Sub-layer: supporting authentication, secure key exchange, and encryption. www.assignmentpoint.com

  47. Long Term Evolution (LTE) Long-term evolution (LTE) standard is one of the newly developed fourth generation standards for mobile communications. In the standard, either frequency division duplexing (FDD) or time division duplexing (TDD) schemes can be used to achieve two-way communications. www.assignmentpoint.com

  48. Evolution of LTE 1G 2G 2.5G 3G 4G www.assignmentpoint.com

  49. Comparison of LTE Speed www.assignmentpoint.com

  50. Features of LTE • The LTE- Advanced (Long Term Evolution- Advanced) is 4G wireless service proposed by 3GPP (Third generation Partnership Project). In 2009 4G LTE started its commercial service in Scandinavia. Three important features of LTE are: femtocell deployment , OFDMA-based physical layer access and MIMO. • The FBS (Femto BS) is named as Home evolved Node-B (HeNB) in LTE-A placed in public places to provide higher data rate and improve resource usage to a number of users. Femtocells are different in the sense that they are installed by customers in an ad hoc fashion without any RF planning. Objective of eNodeB Femtocells lies in off-loading of traffic. www.assignmentpoint.com

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