Orthogonal Sub‐Channels with AMR/DARP

Abstract

The number of GSM subscriptions worldwide reached 4 billion by the end of 2009 [1]. Voice is still one of the most important mobile services and its traffic continues to grow. In order to accommodate this growth, new voice enhancement concepts have continuously been developed for GSM. Both standardized and vendor-specific features have been developed to increase GSM networks' voice capacity. The Spectral Efficiency (SE) has improved many times since the introduction of GSM Phase 1 voice at the beginning of the 1990s. Performance has also improved, for example with more robust speech coding, advanced receivers and concepts allowing more users per channel. Moreover, Radio Resource Management (RRM) methods have been developed in order to optimize the available resources in changing traffic conditions and to fulfill the quality requirements of network operators. High capacity, spectral efficiency, cell coverage, low call drop rate, low blocking probability and high handover success rate are the basic requirements for a network to provide end users with a high quality voice service. In the past few years energy efficiency has also become an increasingly important aspect for network operators.In this chapter, a performance evaluation of GSM voice evolution is presented. The main focus is on the latest voice performance features, namely Orthogonal Sub-Channel (OSC), Voice over Adaptive Multi-user channels on One Slot (VAMOS), Adaptive Multi-Rate (AMR), Single Antenna Interference Cancellation (SAIC) and Downlink Advanced Receiver Performance (DARP). First, an overview of GSM voice evolution is given in Section 8.2. Then, the performance of AMR with SAIC/DARP is presented in Section 8.3. A detailed investigation GSM/EDGE: Evolution and PerformanceEdited by Mikko Säily, Guillaume Sébire and Eddie Riddington

A Decrease of Unsuccessful Pairing Probability in VAMOS Mobile Cell Using Existing Connection Rearrangement

“…The mean connection time is tm = 1/μ, A = λ/μ = λ•t m , and λ is call intensity. It is supposed that pure VAMOS model is implemented, [1], where all active subscribers use VAMOS techniques, i.e. the maximum attainable number of connections is N.…”

“…to allow more connections realization. One limitation of this technique is inability to pair connections, whose downlink emission powers have too different intensity level, [1], [2]. The pairing inability is caused by too great co-channel interference from the paired user, because each user receives his signal and the signal of the paired user, [3].…”

Signaling Enhancement for Machine Type Communications in GERAN Using Orthogonal Sub-Channels

“…The orthogonal sub-channels (OSC) is a technique under standardization process for speech traffic channels [8], in which two users are enabled to transmit in the same channel simultaneously by using different training sequences (TSC). By using this technique in half-rate channels, up to 4 users can share the same resource.…”

“…GERAN feasibility studies focused on determining new training sequences for optimizing capacity improvement as well as new transmit pulse shapes. Additionally, new features related to this concept were developed and are being studied in GERAN over the VAMOS working item [8]. Applications of this technique include increasing the voice capacity in overloaded networks, refarming GSM spectrum for newer technologies [9], and even improvement of perceived voice quality in some specific network scenarios [10].…”

Analysis of DOP in the Presence of PMD and PDL for �RZ/RZ-DPSK Signals in High-Rate Optical Transmission Link

“…It introduces a new channel mode called Double Half Rate (DHR), which is capable of doubling Half Rate (HR) channel's capacity. This improved hardware efficiency turns it possible to reduce the number of circuit switched (CS) resources while maintaining the same voice capacity with similar quality [2].…”