Private:Ahmed Reading Summaries

Will summarize the readings here..

Peer-to-Peer and SVC

• Peer-Driven Video Streaming: Multiple Descriptions versus Layering
• Layered Coding vs. Multiple Descriptions for Video Streaming over Multiple Paths
• Evaluation of the H.264 Scalable Video Coding in Error Prone IP Networks
• Overview of the Scalable Video Coding Extension of the H.264/AVC Standard
• Enabling Adaptive Video Streaming in P2P Systems

Long Term Evolution (LTE)

• Mobile Video Transmission Using Scalable Video Coding
• LTE - An Introduction
• Optimal Transmission Scheduling for Scalable Wireless Video Broadcast with Rateless Erasure Correction Code
• Dynamic Session Control for Scalable Video Coding over IMS
• Mobile Broadband: Including WiMAX and LTE
  • Chapter-11: Long Term Evolution of 3GPP
• 3G Evolution HSPA and LTE for Mobile Broadband
  • Chapter-11: MBMS: Multimedia Broadcast Multicast Service
• The UMTS Long Term Evolution: From Theory to Practice
  • Chapter-2: Network Architecture
  • Chapter-14: Broadcast Operation

Acronyms

• 3GPP 3rd Generation Partnership Project
• BM-SC Broadcast Multicast Service Centre
• CN Core Network
• EPC Evolved Packet Core
• EPS Evolved Packet System
• LTE Long Term Evolution
• MBMS Multimedia Broadcast Multicast Service
• MIMO Multiple Input Multiple Output
• OFDMA Orthogonal Frequency Division Multiple Access
• SAE System Architecture Evolution
• SC-FDMA Single Carrier Frequency Division Multiple Access
• UTRAN UMTS Terrestrial Radio Access Network

Long Term Evolution of 3GPP

LTE PHY Layer

• Based on OFDMA with cyclic prefix in downlink, and on SC-FDMA with a cyclic prefix in the uplink
• Three duplexing modes are supported: full duplex FDD, half duplex FDD, and TDD
• Two frame structure types:
  • Type-1 shared by both full- and half-duplex FDD
  • Type-2 applicable to TDD
• Type-1 radio frame has a length of 10 ms and contains 20 slots (slot duration is 0.5 ms)
• Two adjacent slots constitute a subframe of length 1 ms
• Supported modulation schemes are: QPSK, 16QAM, 64QAM
• Broadcast channel only uses QPSK
• Maximum information block size = 6144 bits
• CRC-24 used for error detection

OFDMA Downlink

• Scheduler in eNB (base station) allocates resource blocks (which are the smallest elements of resource allocation) to users for predetermined amount of time
• Slots consist of either 6 (for long cyclic prefix) or 7 (for short cyclic prefix) OFDM symbols
• Longer cyclic prefixes are desired to address longer fading
• Number of available subcarriers changes depending on transmission bandwidth (but subcarrier spacing is fixed)

[Image Placeholder - Downlink resource block and slot structure]

Evolved Multicast Broadcast Multimedia Services (eMBMS)

• Is a multimedia service performed either with a single-cell broadcast or multicell mode (aka MBMS Single Frequency Network (MBSFN))
• In an MBSFN area, all eNBs are synchronized to perform sumulcast transmission from multiple cells (each cell transmitting identical waveform)
• There are three types of cells within an MBSFN area: transmitting/receiving, transmitting only, and reserved
• If user is close to a base station, delay of arrival between two cells could be quite large, so the subcarrier spacing is reduced to 7.5 KHz and longer CP is used

LTE MAC Layer

• eNB scheduler controls the time/frequency resources for a given time for uplink and downlink
• Scheduler dynamically allocates resources to UEs at each Transmission Time Interval (TTI)
• Depending on channel conditions, scheduler selects best multiplexing for UE
• Downlink LTE considers the following schemes as a scheduler algorithm:
  • Frequency Selective Scheduling (FSS)
  • Frequency Diverse Scheduling (FDS)
  • Proportional Fair Scheduling (PFS)
• Link adaptation is performed through adaptive modulation and coding

MBMS

• Introduced for WCDMA (UMTS) in Release 6
• Supports multicast/broadcast services in a cellular system
• Same content is transmitted to multiple users located in a specific area (MBMS service area) in a unidirectional fashion
• The Broadcast Multicast Service Center (BM-SC) node is responsible for authorization and authentication of content provider, charging, and overall data flow through Core Network (CN)
• In case of multicast, a request to join the session has to be sent to become member of the corresponding MBMS service group
• In contrast to previous releases of Universal Terrestrial Radio Access Network (UTRAN), in MBMS a data stream intended for multiple users is not split until necessary (in UTRAN, one stream per user existed both within CN and RAN)
• MBMS services are power limited and maximize the diversity without relying on feedback from users
• Two techniques are used to provide diversity:
  • Macro-diversity: combining transmission from multiple cells
    • Soft combining: combines the soft bits received from the different radio links prior to (Turbo) coding
    • Selection combining: decoding the signal received from each cell individually, and for each TTI selects one (if any) of the correctly decoded data blocks for further processing by higher layers
  • Time-diversity: against fast fading through a long Transmission Time Interval (TTI) and application-level coding
    • because broadcast cannot rely on feedback, MBMS uses application-level forward error-correcting coding, namely Systematic Raptor codes