Frames FMA2 wideband‐CDMA for UMTS

Toskala, Antti; Castro, Jonathan P.; Dahlman, Erik; Ojanpera, T.

doi:10.1002/ett.4460090407

Cited by 20 publications

(7 citation statements)

References 12 publications

(6 reference statements)

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“…The corresponding personal communications system (PCS) emerging from the currently operational IS-95 system is the so-called cdma2000 arrangement in North America, while the ITU completed the so-called intelligent mobile terminal in the year 2000 recommendation, which is termed as the IMT2000 standard [68]. [60]- [68]: As mentioned above, the radio access scheme of both UMTS and IMT-2000 is wide-band CDMA, and both frequency-division duplex (FDD) and TDD operations are supported. In FDD systems, the uplink (UL) and downlink (DL) signals are transmitted using different carrier frequencies in paired duplex bands.…”

Section: Transmission Issuesmentioning

confidence: 99%

Interactive cellular and cordless video telephony: State-of-the-art system design principles and expected performance

2000

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Second-generation (2G) mobile radio standards have not been designed with video communications in mind, although the employment of error-resilient, constant-bit-rate proprietary video codecs over these systems is realistic. The third-generation (3G) systems I. STATE-OF-THE-ART SYSTEM COMPONENT DEVELOPMENTS A. Introduction and OutlineThe subject of mobile radio communications has reached a state of maturity over the past two decades, as indicated by the excellent monographs by Jakes This contribution attempts to summarize a range of recent advances in the field of bandwidth-efficient wireless video communications. In this section, we commence our discourse with a brief overview of the wireless scene and, in particular, by considering the video transmission capabilities of the existing and future wireless systems. The geographical variation of the cellular channel capacity is characterized by Section II, as a motivation for invoking burst-by-burst adaptive transceivers [27]- [29]. The nature of co-channel interference (CCI)-which is the most dominant channel impairment in wireless systems-is the topic of Section III, where it is shown that the geographic variation of CCI justifies the employment of multimode transceivers, which are discussed in Section IV. Low-rate video compression aspects are reviewed in Section V, and the performance of the ITU H.263 codec is analyzed in some depth. Our discussions in Sections VI and VII are focused on the performance of reconfigurable video transceivers. Specifically, in Section VI, no power control is used-which is typically the case in cordless telephones, such as DECT and CT2-while in Section VII, power control is employed, which is characteristic of cellular systems, such as GSM [30], etc. Section VIII proposes a near-instantaneously adaptive or burst-by-burst adaptive code-division multiple-access (CDMA) scheme, which can be invoked in the context of the forthcoming 3G systems, in order to enhance their performance. Lastly, our discussions are concluded in Section IX with a range of system design guidelines. Let us now commence our overview of the range of existing and forthcoming wireless systems and their video transmission capabilities. B. Second-Generation (2G) Wireless SystemsThe existing 2G wireless systems now constitute a mature technology. Although they have not been designed with video communications in mind, with the advent of the specially designed error-resilient, fixed-rate video codecs [27]-[35] proposed by Streit et al., it is nonetheless realistic to provide videophone services over these low-rate schemes. For low-latency interactive videophony these systems have

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Section: Transmission Issuesmentioning

confidence: 99%

Interactive cellular and cordless video telephony: State-of-the-art system design principles and expected performance

2000

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“…In recent years CDMA has been chosen as multiple access technique in various major modern communication systems [1,2,3,4]. In this paper we investigate a multi-carrier CDMA (MC-CDMA) system [5,6] in an uplink situation.…”

Section: Introductionmentioning

confidence: 99%

Combating Near Far Effects of Linear MMSE Multiuser Detection in Coded OFDM-CDMA

Feuersänger

Kühn

2002

Multi-Carrier Spread-Spectrum &Amp; Related Topics

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This paper deals with near far effects encountered in MMSE linear multiuser detection and proposes a method to mitigate the transmit-power dependent userspecific bit error rates by introducing an additional postprocessing by a combination of nonlinear parallel and successive interference cancellation. Throughout the paper we consider a quasisynchronous (i.e. asynchronous with coarse synchronization at the receiver) OFDM-CDMA uplink transmission as well as perfectly known channel impulse responses.

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“…In the FRAMES FMA2 Wideband CDMA proposal for UMTS [162], different bit rates are accommodated by supporting VSF- [161] and multicode-based operation. In this section, we discuss the employment of VSF codes in adaptive-rate CDMA systems, where the chip rate of the CDMA users is kept constant throughout the transmission, while the bit rate is varied by using spreading codes exhibiting different spreading factors over the course of transmission.…”

Section: Vsf-cdmamentioning

confidence: 99%

Burst-by-burst adaptive multiuser detection cdma: a framework for existing and future wireless standards

Kuan

Hanzo

2003

Proc. IEEE

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This paper provides a broad overview of the multiuser detection literature of the past few years in a nonmathematical, easily accessible approach. The treatment is then extended to the comparative study of channel-quality controlled burst-by-burst (BbB) adaptive code division multiple access (CDMA) detection such as parallel interference cancellation, successive interference cancellation, and joint detection (JD I. MOTIVATIONMobile propagation channels exhibit time-variant propagation properties [1]. Although, apart from simple cordless telephoneschemes,mostmobileradiosystemsemploypowercontrol for mitigating the effects of received power fluctuations, rapid channel quality fluctuations cannot be compensated by practical, finite reaction-time power control schemes. Furthermore, the ubiquitous phenomenon of signal dispersion due to the multiplicity of scatering and reflecting objects cannot be mitigated by power control. Similarly, other performance lim- iting factors, such as adjacent-channel and cochannel intereference as well as multiuser interference (MUI) vary as a function of time. The ultimate channel quality metric is the bit-error rate (BER), regardless of the specific channel impairments encountered. The channel quality variations are typically higher near the fringes of the propagation cell or when moving from an indoor scenario to an outdoor cell due to the high standard deviation of the shadow fading and fast fading [1] encountered, even in conjunction with agile power control. Furthermore, the bit errors typically occur in bursts due to the time-variant channel quality fluctuations; hence, it is plausible that a fixed transceiver mode cannot achieve a high flexibility in such environments. The design of powerful and flexible transceivers [2]-[4] has to be based on finding the best compromise among a number of contradicting design factors [2]- [4]. Some of these factors are low power consumption, high robustness against transmission errors among various channel conditions, high spectral efficiency, low-delay for the sake of supporting interactive real-time multimedia services, high-capacity networking, and so forth [5]. In this paper, we will address a few of these issues in the context of direct sequence code division multiple access [6] (DS-CDMA) systems, 1 since CDMA is the solution standardized in all three recently ratified global mobile 1 The simple philosophy of DS-CDMA is that a binary bit of a user is signaled to the receiver with the aid of a unique, user-specific signature sequence. The DS spreading sequences may be chosen such that they are orthogonal to each other; hence, the individual users' signals do not interfere with each other, provided that the transmission channel does not destroy the orthogonality of the DS spreading sequences. When the orthogonality of the DS spreading codes is retained at the receiver, no MUI is inflicted; hence, a simple correlator is capable of detecting the codes of the users conveying the information with the aid of the code's polarity. By contrast, if the...

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Frames FMA2 wideband‐CDMA for UMTS

Cited by 20 publications

References 12 publications

Interactive cellular and cordless video telephony: State-of-the-art system design principles and expected performance

Interactive cellular and cordless video telephony: State-of-the-art system design principles and expected performance

Combating Near Far Effects of Linear MMSE Multiuser Detection in Coded OFDM-CDMA

Burst-by-burst adaptive multiuser detection cdma: a framework for existing and future wireless standards

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