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Device-to-Device (D2D) is considered as a promising technique to improve resource utilization and provide new application in future wireless networks. This paper addresses the problem of radio resource allocation for D2D communication. Basically, resource allocation can be carried out in centralized or distributed manner. In this paper we discuss the mechanisms of distributed resource allocation and...
In this work, we introduce a novel multiple access scheme which is based on the joint design of the system signature matrix at the transmitter and the successive interference cancelation (SIC) based detector at the receiver. The symbols of the different users are judiciously spread in the frequency (space) domain, which can be effectively exploited by the SIC based technique, such as the iterative...
In this paper, a novel joint decision-feedback equalizer (DFE) with progressive group detection (PGD) assistance is proposed for downlink MIMO spatial multiplexing systems under frequency-selective fading channels. The proposed DFE operates on chip-level to accommodate CDMA wideband systems employing short and long scrambling codes over frequency-selective channels. PGD is a near-maximum likelihood...
With the unrelenting demand for high bandwidth and high spectrum efficiency, intercell interference (ICI) becomes more and more serious and ICI management plays an increasingly important role in mobile cellular networks. This paper overviews the main ICI management schemes employed in the 2nd generation (2G) to the fourth generation (4G) mobile communication systems, such as the basic frequency reuse-n...
In this paper, a novel spectrum refarming (SR) system is proposed in which the Orthogonal Frequency Division Multiple Access (OFDMA) small cells overlay the Code Division Multiple Access (CDMA) cellular networks in the same legacy CDMA spectrum. In order to predict and control the interferences from the OFDMA small cells to the CDMA macrocell, the OFDMA downlink transmissions in the small cells are...
We consider ad hoc wireless networks that use frequency hopping to provide multiple access capability among radios. In such systems, the multiple-access control (MAC) protocol must be designed to provide an appropriate level of simultaneous transmissions to efficiently utilize the channel, while not causing so much multiple-access interference that data transmissions cannot be decoded correctly. The...
In this paper, an energy-aware routing algorithm based on renewal process is proposed to choose highly competitive solutions for routing performance in cognitive radio ad hoc networks (CRANs). Moreover, we propose a new medium access scheme through spectrum forecast for secondary users to access the primary users' channels. Thereby, the proposed algorithm can allow selected routes corresponding to...
This paper describes a successive multiuser detection technique for Direct Sequence Code Division Multiple Access (DS-CDMA) systems. In conventional CDMA system, single-user detection is employed, so that the interference between users or multiple access interference (MAI) component is considered as noise, which contributes to the statistics of detection variables affecting the quality of detection...
This paper proposes variable step closed loop power control algorithm combined with space diversity to improve the performance of High Altitude Platforms (HAPs) communication at low elevation angle using Code Division Multiple Access (CDMA). In this contribution, we first develop HAPs channel model which is derived from experimental measurement. From our experiment, we found HAPs channel characteristic...
A zero-correlation zone (ZCZ) sequence set consisting of multiple ZCZ sequence subsets is said to be an asymmetric ZCZ (A-ZCZ) sequence set if and only if the cross-correlation function (CCF) between two arbitrary sequence which belong to different subsets has quite a large zero-cross-correlation zone (ZCCZ). In such an A-ZCZ sequence set, each subset is a conventional ZCZ sequence set. Our proposed...
Code division multiple access (CDMA) is one of the promising techniques in cellular mobile communications system used for radio accessing and personal communication systems. Besides several practical advantages, CDMA suffers with multiuser interference, limiting the spectral efficiency drastically. There are various optimal and suboptimal multi user detection techniques in CDMA to overcome this problem...
Carrier aggregation and multi-flow transmission are among the most important features of HSPA+. While the former allows users to be served simultaneously by several carriers in the same sector, the latter enables adjacent sectors to simultaneously schedule different data streams to the same user in their overlapping region. In this paper, we investigate the inter-operation of these two features. We...
SEAMCAT is a statistical simulation model that uses Monte Carlo analysis method to assess the potential interference between different radio communication systems. SEAMCAT can consider system-level simulation for CDMA and OFDMA system.
Code Division Multiple Access (CDMA) aims at the simultaneous transmissions among mobile stations using orthogonal spreading codes where the spatial reuse of the codes is considered for the reduction of code requirement. Code assignment should be such that the communication performance of the network is improved where no code assignment interference is allowed. There exists three code assignment techniques...
In this paper we study unslotted ALOHA optical code division multiple access (CDMA) packet switching local area network (LAN). The system uses on-off keying (OOK) and M-ary overlapping pulse position modulation (OPPM) as signaling schemes. Generalized and strict optical orthogonal codes (OOC) are used to implement CDMA concept. The generated packets are assumed to have variable length. The impact...
Random spatial network models have been recently utilized in the performance analysis and system design for multi-cell networks. Such an approach has been mainly adopted to investigate the outage based system performance, such as the outage probability and outage throughput. However, these performance metrics are defined with a fixed-rate transmission, and cannot characterize the performance of data...
In WLAN systems, distributed coordination function (DCF) is used to avoid transmission collision. When an error occurs, the transmitter extends its contention window for the next retransmission to avoid more errors. But this may cause an unfairness problem; in noisy conditions MTs may find it difficult to get transmission opportunities, especially in a heterogeneous network with a large number of...
Multi-User Coordinated Multi-Point (MU-CoMP) transmission mode is considered as one of the key technologies which offer a good quality of service to low capacity users while maintaining a high spectral efficiency in the system. However, MU-CoMP networks have to determine the total number of users supported by CoMP operation as well as the size of the SDMA (Spatial Division Multiple Access) users'...
In this paper, we consider a multirate teletraffic loss model for the calculation of congestion probabilities in a Wideband Code Division Multiple Access (W-CDMA) cell that utilizes the Bandwidth Reservation (BR) policy and supports calls generated by a finite number of users. The BR policy is used particularly to equalize congestion probabilities among calls of different service-classes. In the proposed...
In this paper a Media Aware Radio Link Adaptation (MARLA) scheme for H.264/AVC video transmission is proposed to improve the video delivery quality over HSDPA networks. First of all, by taking both the packet importance and urgency into consideration, we design a transmission utility function to measure the packet priority. Secondly, an optimization model for radio link adaptation is built to maximize...
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