Orthogonal Frequency Division Multiplexing (OFDM) is used for both 802.11 and 802.16 wireless network standards and is being evaluated for Fourth Generation (4G) networks such as those being proposed in the 3GPP and 3GPP2 wireless standards bodies. In both uplink and downlink directions, resources can be allocated in three dimensions, frequency, time and power. The uplink resource allocation pr...

Smart antennas can be used to increase the capacity, the link quality and the coverage of existing and future cellular mobile communication networks. Several sophisticated uplink algorithms have been proposed for beamforming and signal detection. But downlink beamforming seems to be the bottleneck of the applicability of adaptive antennas in cellular mobile communication systems. Obviously, a s...

This paper analyzes dynamic channel assignment in cellular systems where the base stations are placed at random. Using a simple dynamic channel assignment algorithm, random systems are compared to an ideal hexagonal systems. Under log-normal shadow fading the random system has capacity within 1dB of the hexagonal system. This paper looks at both the uplink and downlink and finds that performanc...

In order to meet the transmission needs of WDM-PON system, a full-duplex system based on reflective semiconductor optical amplifier (RSOA) remodulation was constructed in this paper. The downlink rate 40Gb/s, and adopted three modulation formats, namely carrier suppression return zero (CSRZ), duobinary (ODB) quadrary pulse amplitude (PAM4); uplink 10Gb/s, NRZ code. Through simulation, performan...

We consider a single station (STA) in the Power Save Mode (PSM) of an IEEE 802.11 infrastructure WLAN. This STA is assumed to be carrying uplink and downlink traffic via the access point (AP). We assume that the transmission queues of the AP and the STA are saturated, i.e., the AP and the STA always have at least one packet to send. For this scenario, it is observed that uplink and downlink thr...

In this paper, a routing protocol is proposed that provides location privacy for the source and the destination as well as user anonymity and unlinkability in multihop wireless sensor networks. The sink is assumed to be computationally powerful and responsible for all routing decisions. It assigns incoming and outgoing labels to nodes in the uplink and downlink directions. Each node is only awa...

In this paper, we propose a coordinated pilot reuse (CPR) approach to reduce the pilot overhead for multi-cell massive multi-input multi-output transmission. Unlike the conventional multi-cell pilot reuse approach in which pilots can only be reused among different cells, the proposed CPR approach allows pilots to be reused among both inter-cell and intra-cell user equipments, and thus, pilot ov...

In order to transition from today’s 3rd generation (3G) communications systems to meet the needs of 4th generation (4G) systems, the 3rd Generation Partnership Partnership (3GPP) has released the Long Term Evolution (LTE) specification. Among the numerous differences between these generations are changes in the physical layer (PHY), specifically in the modulation and multiple access schemes. Wh...

In this paper, we present a code-division multiple access (CDMA) system with a spreading factor of N that can accommodate up to mN users, where m 2. The m sets of orthogonal spreading sequences are constructed by overlaying the same N orthogonal Walsh-Hadamard sequences with a set-specific pseudonoise (PN) sequence. Interference between user signals from different sets is cancelled by means of ...

Implicit feedback is an approach that utilizes uplink channel state information (CSI) for downlink transmit beamforming on multiple-input multiple-output (MIMO) systems, relying on over-the-air channel reciprocity. The implicit feedback improves throughput efficiency because overhead of CSI feedback for change of over-the-air channel responses is omitted. However, it is necessary for the implic...