A decentralized approach for self-coexistence among heterogeneous networks in TVWS

IEEE This paper focuses on coexistence and self- coexistence challenges between secondary heterogeneous wireless networks/users sharing TV Whitespace spectrum. The coexistence problems arise from having several primary and secondary networks of different technologies cohabiting the same licensed spectrum simultaneously. The self- coexistence problems arise from many secondary systems /users coexisting at the same place while using identical or different technologies. In particular, fair distribution of available spectrum becomes a serious issue. In this work we use a game theoretic approach to model the self-coexistence problem as a competitive game between secondary networks. We show that our game belongs to the class of congestion-averse games which are known to posses pure Nash Equilibria. This leads us to a decentralized approach for spectrum sharing among systems with different PHY/MAC characteristics. We show that our proposal outperforms other centralized algorithms in terms of user fairness and per-user theoretical data rates

Interference-Aware Resource Scheduling in LTE HetNets with Carrier Aggregation Support

Optimal resource allocation in LTE networks is known to be a hard problem, and is further exacerbated when support for advanced features such as heterogeneity and carrier aggregation are also considered. In particular, in LTE heterogeneous networks (HetNets) where radio resources are shared between different layers of base stations, interference management can be a daunting task. Carrier aggregation (CA), which allows the simultaneous use of several LTE component carriers to achieve high user data rates, also adds to the complexity. In this paper, we propose an interference-aware heuristic algorithm that jointly performs carrier selection and resource allocation to serve a mix of users with CA-enabled and legacy terminals. We evaluate the performance of our approach in a large-scale scenario and compare it with other widely used heuristic algorithms such as Proportional-Fair scheduling and Enhanced Inter Cell Interference Coordination (eICIC) techniques. Simulation results show that the solution we propose increases system throughput, minimises energy consumption and improves spectrum utilisation, while also ensuring better fairness between CA-enabled and legacy user terminals

Fast resource scheduling in HetNets with D2D support

Resource allocation in LTE networks is known to be an NP-hard problem. In this paper, we address an even more complex scenario: an LTE-based, 2-tier heterogeneous network where D2D mode is supported under the network control. All communications (macrocell, microcell and D2D-based) share the same frequency bands, hence they may interfere. We then determine (i) the network node that should serve each user and (ii) the radio resources to be scheduled for such communication. To this end, we develop an accurate model of the system and apply approximate dynamic programming to solve it. Our algorithms allow us to deal with realistic, large-scale scenarios. In such scenarios, we compare our approach to today's networks where eICIC techniques and proportional fairness scheduling are implemented. Results highlight that our solution increases the system throughput while greatly reducing energy consumption. We also show that D2D mode can effectively support content delivery without significantly harming macrocells or microcells traffic, leading to an increased system capacity. Interestingly, we find that D2D mode can be a low-cost alternative to microcells

Uplink and Downlink Resource Allocation in D2D-Enabled Heterogeneous Networks

We address the problem of uplink and downlink resource allocation in heterogeneous networks where device-to-device (D2D) communication is allowed. We consider a realistic, large-scale LTE network in which users can download/upload data using different paradigms, namely, downlink/uplink transmissions from/to macro or micro base stations, and D2D communication in the uplink LTE bands. We propose an approximate dynamic programming algorithm to perform resource allocation scheduling for both upload and download data traffic, while taking into account the interference caused by resource sharing between the different data transfer paradigms. Through simulation, we compare the performance of our approach to solutions employed in today's networks, such as eICIC techniques and proportional fairness scheduling. Results show that our approach significantly improves the system performance in terms of both overall throughput and energy efficiency

Suture repair of umbilical hernia during caesarean section: a case-control study

PURPOSE: The objective of this study was to investigate the additional burdens in terms of pain, prolongation of surgery and morbidity which is added to elective caesarean section if umbilical hernia suture repair is performed simultaneously. Secondly, patient's satisfaction and hernia recurrence rate were assessed. METHODS: Consecutive women with symptomatic umbilical hernia undergoing internal or external suture repair during elective caesarean were included in this retrospective cohort-control study. Data on post-operative pain, duration of surgery and morbidity of a combined procedure were collected. These patients were matched 1:10 to women undergoing caesarean section only. Additionally, two subgroups were assessed separately: external and internal suture hernia repair. These subgroups were compared for patient's satisfaction, cosmesis, body image and recurrence rate. RESULTS: Fourteen patients with a mean age of 37 years were analysed. Internal suture repair (n = 7) prolonged caesarean section by 20 min (p = 0.001) and external suture repair (n = 7) by 34 min (p < 0.0001). Suture repair did not increase morphine use (0.38 ± 0.2 vs. 0.4 ± 02 mg/kg body weight), had no procedure-related morbidity and prolonged hospitalization by 0.5 days (p = 0.01). At a median follow-up of 37 (5-125) months, two recurrences in each surgical technique, internal and external suture repair, occurred (28 %). Body image and cosmesis score showed a higher level of functioning in internal suture repair (p = 0.02; p = 0.04). DISCUSSION: Despite a high recurrence rate, internal suture repair of a symptomatic umbilical hernia during elective caesarean section should be offered to women if requested. No additional morbidity or scar is added to caesarean section. Internal repair is faster, and cosmetic results are better, additional skin or fascia dissection is avoided, and it seems to be as effective as an external approach. Yet, women must be informed on the high recurrence rate