| 1. |
- Holmberg, Robert, et al.
(author)
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Rethinking Production Games
- 1998
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In: Concepts and Transformation. - 1384-6639. ; 3:3, s. 271-282
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Journal article (peer-reviewed)
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| 2. |
- Karlsson, Robert S., et al.
(author)
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Hierarchical Cell Structure for FRAMES Wideband Wireless Access
- 1996
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In: Conf. Proc. ACTS Mobile Telecommunications Summit 96. ; , s. 785-791
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Conference paper (peer-reviewed)abstract
- To provide sufficient capacity in traffic hot spots, small micro cells are needed to complement macro cells providing low cost large area coverage. These problems can be solved by using a mixed cell structure with macro cells for coverage and micro cells for capacity. Such a scenario, where coverage is provided from both macro and micro cells in a large part of the service area, is often referred to as an HCS (Hierarchical Cell Structure). One common way to provide radio resource management in an HCS scenario is to divide the available spectrum between the two cell layers into one macro cell band and one micro cell band. The key problem in these scenarios is that due to the large dynamic range of received signals, the suppression of inter-band interference may not be sufficient to provide adequate Signal-to-interference ratios at all times. The unwanted radiation of high power macro cell terminals into the micro cell band may cause severe difficulties to the micro cell base station receivers, tuned to the low power micro cell terminals. In the paper, three candidate multi-access schemes proposed in the ACTS FRAMES project were studied using a simple macro/micro cell scenario in order to assess the width of these problems. Results indicate that there are no major performance differences between the different schemes for the up-link scenario. The down-link scenario was shown to yield much worse results than the up-link scenario and only the CATS2 and the narrowband SMA1 schemes were achieving acceptable performance at a very low noise floor.
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| 3. |
- Karlsson, Robert S., et al.
(author)
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Hierarchical Cell Structures for Future Wideband Wireless Access
- 1997
-
Conference paper (peer-reviewed)abstract
- To provide sufficient capacity in traffic hot spots, small micro cells are needed to complement macro cells providing low cost large area coverage. These problems can be solved by using a mixed cell structure with macro cells for coverage and micro cells for capacity. Such a scenario, where coverage is provided from both macro and micro cells in a large part of the service area, is often referred to as an HCS (Hierarchical Cell Structure). One common way to provide radio resource management in an HCS scenario is to divide the available spectrum between the two cell layers into one macro cell band and one micro cell band. The key problem in these scenarios is that due to the large dynamic range of received signals, the suppression of inter-band interference may not be sufficient to provide adequate Signal-to-interference ratios at all times. The unwanted radiation of high power macro cell terminals into the micro cell band may cause severe difficulties to the micro cell base station receivers, tuned to the low power micro cell terminals. In the paper, three candidate multi-access schemes proposed for the third generation systems in the ACTS FRAMES project were studied using a simple macro/micro cell scenario in order to assess the width of these problems. Results indicate that there are no major performance differences between the different schemes for the up-link scenario. The down-link scenario was shown to yield much worse results than the up-link scenario and only the CATS2 and the narrow band SMA1 schemes were achieving acceptable performance at a very low noise floor. The power control scheme is very important for the performance. When using SIR balanced power control the outage caused by external interference is gradually increasing as the interference increases. If constant received power control is used the system will work as long as the external interference is below a certain level and when interference increases above this level the outage will increase rapidly.
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| 4. |
- Karlsson, Robert S.
(author)
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Resource Sharing and Capacity of Some Multiple Access Methods in Hierarchical Cell Structures
- 1999
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In: Vehicular Technology Conference, 1999. VTC 1999 - Fall. IEEE VTS 50th. - New York : IEEE. - 0780354354 ; , s. 2825-2829
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Conference paper (peer-reviewed)abstract
- To decrease total system cost and improve efficiency, in future mobile communication systems, we can implement a structure of multiple cells covering an area. This is often referred to as a hierarchical cell structure, HCS. We compare five methods of sharing the scarce radio resources in a two-layer HCS: (i) DS-CDMA in macrocells and TDMA in microcells; (ii) TDMA in macrocells and DS-CDMA in microcells; (iii) DS-CDMA in both macrocells and microcells on the same frequency band; (iv) TDMA in both layers with frequency splitting; and (v) TDMA in both layers with reuse of macro frequencies in microcells. Through simulation we study the system capacities, i.e., the number of users supported per cell. Highest capacities are achieved by method (iv) and (v). Method (v) could also be used in a CDMA type of system if it is possible to have more than one carrier.
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| 5. |
- Karlsson, Robert S.
(author)
-
Sharing radio resources in hierarchical cell structures utilizing slow frequency hopping
- 1999
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In: Vehicular Technology Conference, 1999 IEEE 49th. - New York : IEEE. - 0780355652 ; , s. 412-416
-
Conference paper (peer-reviewed)abstract
- One way to decrease total system cost and improve efficiency in future mobile communication systems is a structure with cells covering the same area. This is often referred to as a hierarchical cell structure, HCS. We investigate the novel option of using slow frequency hopping, SFH, to combat interference between layers in an HCS where the same spectrum is used in all layers to avoid trunking losses and frequency planning between layers. We compare, in terms of capacity, the alternative of splitting the available bandwidth in separate parts. Results show that SFH manages to handle the inter-layer interference of an HCS if adequate admission and power control is used, but splitting the spectrum gives higher capacity.
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| 6. |
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