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We study the transmission capacity of two overlaid wireless ad hoc networks, where a primary network and a secondary network operate in the same geographic region and share the same spectrum. The primary network has a high priority to access the spectrum and is oblivious of the presence of the secondary network while the secondary network limits its interference to the primary network by controlling...
This paper studies the opportunistic spectrum access (OSA) of secondary users in a large-scale overlay cognitive radio network. Particularly, a threshold-based protocol is investigated, where the secondary transmitter is allowed to access the spectrum only if the maximum signal power of the received beacons transmitted by the primary receivers is lower than a certain threshold. To measure the resulting...
This paper studies the opportunistic spectrum access (OSA) of secondary users in a large-scale overlay cognitive radio (CR) network. Particularly, a threshold-based protocol is investigated, where the secondary transmitter is allowed to access the spectrum only if the maximum signal power of the received pilots sent from the primary transmitters is lower than a certain threshold. To measure the resulting...
In this paper, we propose a selection region based multihop routing protocol with directional antennas for wireless mobile ad hoc networks, where the selection region is defined by two parameters: a reference distance and the beamwidth of the directional antenna. At each hop, we choose the nearest node to the transmitter within the selection region as the next hop relay. By maximizing the expected...
We propose a selection region based multi-hop routing protocol for random mobile ad hoc networks, where the selection region is defined by two parameters: a reference distance and a selection angle. At each hop, a relay is chosen as the nearest node to the transmitter that is located within the selection region. By assuming that the relay nodes are randomly placed, we derive an upper bound for the...
We study the effect of channel inversion based power control on the transmission capacities of two coexisting wireless networks (a primary network vs. a secondary network) that operate in the same geographic region and share the same spectrum. The primary (PR) network has a higher priority to access the spectrum without particular considerations for the secondary (SR) network, where the SR network...
In this paper, the transmission capacities of two coexisting wireless networks (primary network and secondary network) in the same geographic region and sharing the same spectrum are derived. The primary (PR) network has a higher priority to access the spectrum, while the secondary (SR) network limits its interference to the PR network by controlling its transmission intensity. Considering spread-spectrum...
In this paper, we investigate and research turbo coding for Bell Lab's Layered Space Time (BLAST) system and propose its encoding and decoding structure. Vertical BLAST (VBLAST) is a important method among BLAST to improve greatly system channel capacity, but because of its interference between transmit antennas, BER (FER) is sharply decreasing. At the receiver, we apply iterative ordered zero-forcing...
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