| 1. |
- Chen, Jingjing, 1982, et al.
(author)
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Experimental demonstration of RF-pilot-based phase noise mitigation for millimeter-wave systems
- 2014
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In: IEEE Vehicular Technology Conference. - 1550-2252. - 9781479944491 ; , s. Art. no. 6965978-
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Conference paper (peer-reviewed)abstract
- Millimeter-wave bands are gaining popularity for high data rate wireless communication systems due to the wide available bandwidth. However, oscillator phase noise also increases as the carrier frequency increases. Methods of phase noise mitigation are therefore crucial for future millimeter-wave systems. In this work, we propose to adopt analog phase noise mitigation using an RF-pilot tone, which reduces both phase and frequency impairments of an arbitrary millimeter-wave signal at the expense of reduced spectral efficiency. The method is verified experimentally at carrier frequency of 28 GHz and E-band 73 GHz showing a 20 dB noise reduction up to 100 kHz offset. Since the method relaxes phase noise requirement it is attractive for phase noise sensitive technologies at high carrier frequency, such as OFDM used in LTE. As indicated by the simulation results, the reduced phase noise enables a LTE signal on a millimeter-wave carrier with marginal performance impact.
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| 2. |
- Gevorgian, Spartak, 1948, et al.
(author)
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Tunable delay line arrangement
- 2013
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Other publication (other academic/artistic)abstract
- A tunable chirped delay line arrangement (0) configured to operatively propagate a signal and includes a at least one chirped delay line (1) arranged along a reference direction (z) on a dielectric layer (2) arranged on a ground plane (3). The chirped delay line (1) is configured with a smoothly varying width along the reference direction (z), and the arrangement (0) further comprising at least one electronically tunable impedance (5) interconnecting the at least one delay line (1) and the ground plane (3) at at least one location along the reference direction (z) such that the at least one delay line (1) is loaded by the tunable impedance
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| 3. |
- Gustavsson, Johan, 1974, et al.
(author)
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High-speed 850-nm VCSELs for 40 Gb/s transmission
- 2010
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Conference paper (other academic/artistic)abstract
- We have explored the possibility to extend the data transmission rate for standard 850-nm GaAs-based VCSELs beyond the 10 Gbit/s limit of today's commercially available directly-modulated devices. By sophisticated tailoring of the design for high-speed performance we demonstrate that 10 Gb/s is far from the upper limit. For example, the thermal conductivity of the bottom mirror is improved by the use of binary compounds, and the electrical parasitics are kept at a minimum by incorporating a large diameter double layered oxide aperture in the design. We also show that the intrinsic high speed performance is significantly improved by replacing the traditional GaAs QWs with strained InGaAs QWs in the active region. The best overall performance is achieved for a device with a 9 μm diameter oxide aperture, having in a threshold current of 0.6 mA, a maximum output power of 9 mW, a thermal resistance of 1.9 °C/mW, and a differential resistance of 80 Ω. The measured 3dB bandwidth exceeds 20 GHz, and we experimentally demonstrate that the device is capable of error-free transmission (BER
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| 4. |
- Olsson, Daniel S, 1983, et al.
(author)
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Tumour recurrence and enlargement in patients with craniopharyngioma with and without GH replacement therapy during more than 10 years of follow-up.
- 2012
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In: European journal of endocrinology. - 1479-683X. ; 166:6, s. 1061-8
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Journal article (peer-reviewed)abstract
- Most patients who have been treated for craniopharyngioma (CP) are GH deficient (GHD). GH replacement therapy (GHRT) may stimulate tumour regrowth; and one of the concerns with long-term GHRT is the risk of tumour progression. Therefore, the objective was to study tumour progression in CP patients on long-term GHRT.Case-control study.The criteria for inclusion of cases were: i) GHD caused by CP; ii) GHRT >3 years; and iii) regular imaging. This resulted in 56 patients (mean age at diagnosis 25±16 years) with a mean duration of GHRT of 13.6±5.0 years. As controls, 70 CP patients who had not received GHRT were sampled with regard to follow-up, gender, age at diagnosis and initial radiation therapy (RT).The 10-year tumour progression-free survival rate (PFSR) for the entire population was 72%. There was an association (hazard ratio, P value) between PFSR and initial RT (0.13, 0.001) and residual tumour (3.2, 0.001). The 10-year PFSR was 88% for the GHRT group and 57% for the control group. Substitution with GHRT resulted in the following associations to PFSR: GHRT (0.57, 0.17), initial RT (0.16, <0.001), residual tumour (2.6, <0.01) and gender (0.57, 0.10). Adjusted for these factors, the 10-year PFSR was 85% for the GHRT group and 65% for the control group.In patients with CP, the most important prognostic factors for the PFSR were initial RT and residual tumour after initial treatment. Long-term GHRT did not affect the PFSR in patients with CP.
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| 6. |
- Toft, Fredrik, 1986, et al.
(author)
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Feasibility study of FPGA-based equalizer for 112-Gbit/s optical fiber receivers
- 2012
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In: ISCAS 2012 - 2012 IEEE International Symposium on Circuits and Systems. - 9781467302180 ; , s. 3234-3237
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Conference paper (peer-reviewed)abstract
- With ever increasing demands on spectral efficiency, complex modulation schemes are being introduced in fiber communication. However, these schemes are challenging to implement as they drastically increase the computational burden at the fiber receiver's end. We perform a feasibility study of implementing a 16-QAM112-Gbit/s decision directed equalizer on a state-of-the-art FPGA platform. An FPGA offers the reconfigurability needed to allow for modulation scheme updates, however, its clock rate is limited. For this purpose, we introduce a new phase correction technique to significantly relax the delay requirement on the critical phase-recovery feedback loop.
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