Backward compatibility

Abstract: The UMTS terrestrial radio access is based on wideband 4.096 Mchip/s DS-CDMA technology. UTRA will be connected to an evolved GSM core network for both circuit and packet services. A merger between ETSI/Europe and ARIB/Japan based on W-CDMA, a GSM core network, and a common frequency allocation according to the ITU Recommendation of 2 GHz makes a global IMT-2000 standard feasible. UTRA based on W-CDMA fully supports the UMTS/IMT-2000 requirements (e.g., support of 384 kb/s for wide-area coverage and 2 Mb/s for local coverage). Furthermore, the air interface has flexible support of mixed services, variable-rate services, and an efficient packet mode. Key W-CDMA features also include improved basic capacity/coverage performance compared to second-generation systems, full support of adaptive antenna arrays, support of hierarchical cell structures with interfrequency handover, and support of asynchronous inter-base-station operation. There have been no constraints due to the strong requirements for backward compatibility with second-generation systems. This has facilitated a high degree of flexibility and a future-proof air interface. Extensive evaluations by means of simulations and field trials have been carried out by a number of companies, and full system tests are ongoing. Consequently, W-CDMA technology can now be regarded as a mature technology, ready to provide the basis for UMTS/IMT-2000.

Abstract: Preface. Chapter 1. An Introduction to Device Drivers The Role of the Device Driver Splitting the Kernel Classes of Devices and Modules Security Issues Version Numbering License Terms Joining the Kernel Development Community Overview of the Book. Chapter 2. Building and Running Modules Kernel Modules Versus Applications Compiling and Loading The Kernel Symbol Table Initialization and Shutdown Using Resources Automatic and Manual Configuration Doing It in User Space Backward Compatibility Quick Reference. Chapter 3. Char Drivers The Design of scull Major and Minor Numbers File Operations The file Structure open and release scull's Memory Usage A Brief Introduction to Race Conditions read and write Playing with the New Devices The Device Filesystem Backward Compatibility Quick Reference. Chapter 4. Debugging Techniques Debugging by Printing Debugging by Querying Debugging by Watching Debugging System Faults Debuggers and Related Tools. Chapter 5. Enhanced Char Driver Operations ioctl Blocking I/O poll and select Asynchronous Notification Seeking a Device Access Control on a Device File Backward Compatibility Quick Reference. Chapter 6. Flow of Time Time Intervals in the Kernel Knowing the Current Time Delaying Execution Task Queues Kernel Timers Backward Compatibility Quick Reference. Chapter 7. Getting Hold of Memory The Real Story of kmalloc Lookaside Caches get_free_page and Friends vmalloc and Friends Boot-Time Allocation Backward Compatibility Quick Reference Chapter 8. Hardware Management I/O Ports and I/O Memory Using I/O Ports Using Digital I/O Ports Using I/O Memory Backward Compatibility Quick Reference. Chapter 9. Interrupt Handling Overall Control of Interrupts Preparing the Parallel Port Installing an Interrupt Handler Implementing a Handler Tasklets and Bottom-Half Processing Interrupt Sharing Interrupt-Driven I/O Race Conditions Backward Compatibility Quick Reference. Chapter 10. Judicious Use of Data Types Use of Standard C Types Assigning an Explicit Size to Data Items Interface-Specific Types Other Portability Issues Linked Lists Quick Reference. Chapter 11. kmod and Advanced Modularization Loading Modules on Demand Intermodule Communication Version Control in Modules Backward Compatibility Quick Reference. Chapter 12. Loading Block Drivers Registering the Driver The Header File blk.h Handling Requests: A Simple Introduction Handling Requests: The Detailed View How Mounting and Unmounting Works The ioctl Method Removable Devices Partitionable Devices Interrupt-Driven Block Drivers Backward Compatibility Quick Reference. Chapter 13. mmap and DMA Memory Management in Linux The mmap Device Operation The kiobuf Interface Direct Memory Access and Bus Mastering Backward Compatibility Quick Reference. Chapter 14. Network Drivers How snull Is Designed Connecting to the Kernel The net_device Structure in Detail Opening and Closing Packet Transmission Packet Reception The Interrupt Handler Changes in Link State The Socket Buffers MAC Address Resolution Custom ioctl Commands Statistical Information Multicasting Backward Compatibility Quick Reference. Chapter 15. Overview of Peripheral Buses The PCI Interface A Look Back: ISA PC/104 and PC/104+ Other PC Buses SBus NuBus External Buses Backward Compatibility Quick Reference. Chapter 16. Physical Layout of the Kernel Source Booting the Kernel Before Booting The init Process The kernel Directory The fs Directory The mm Directory The net directory ipc and lib include and arch Drivers. Glossary. Index

Abstract: Driven by the need to cope with exponentially growing mobile data traffic and to support new traffic types from massive numbers of machine-type devices, academia and industry are thinking beyond the current generation of mobile cellular networks to chalk a path towards fifth generation (5G) mobile networks. Several new approaches and technologies are being considered as potential elements making up such a future mobile network, including cloud RANs, application of SDN principles, exploiting new and unused portions of spectrum, use of massive MIMO and full-duplex communications. Research on these technologies requires realistic and flexible experimentation platforms that offer a wide range of experimentation modes from real-world experimentation to controlled and scalable evaluations while at the same time retaining backward compatibility with current generation systems. Towards this end, we present OpenAirInterface (OAI) as a suitably flexible platform. In addition, we discuss the use of OAI in the context of several widely mentioned 5G research directions.

Abstract: In order to achieve up to 1 Gb/s peak data rate in future IMT-Advanced mobile systems, carrier aggregation technology is introduced by the 3GPP to support very-high-data-rate transmissions over wide frequency bandwidths (e.g., up to 100 MHz) in its new LTE-Advanced standards. This article first gives a brief review of continuous and non-continuous CA techniques, followed by two data aggregation schemes in physical and medium access control layers. Some technical challenges for implementing CA technique in LTE-Advanced systems, with the requirements of backward compatibility to LTE systems, are highlighted and discussed. Possible technical solutions for the asymmetric CA problem, control signaling design, handover control, and guard band setting are reviewed. Simulation results show Doppler frequency shift has only limited impact on data transmission performance over wide frequency bands in a high-speed mobile environment when the component carriers are time synchronized. The frequency aliasing will generate much more interference between adjacent component carriers and therefore greatly degrades the bit error rate performance of downlink data transmissions.